FON 241: Chapter 9 & 10

What is the pH that our blood/acid-base balance should be?

7.35 to 7.45

Thirst Mechanism

A cluster of nerve cells in the hypothalamus that stimulates our conscious desire to drink fluids in response to an increase in the concentration of salt in our blood or a decrease in blood pressure and blood volume. Prompted by: • Increased concentration of salt and other dissolved substances in the blood. Remember that ham sandwich and those potato chips? Both of these foods are salty, and eating them increased the blood's sodium concentration. • A reduction in blood volume and blood pressure. This can occur when fluids are lost through profuse sweating, blood loss, vomiting, diarrhea, or simply when fluid intake is too low. • Dryness in the tissues of the mouth and throat. Tissue dryness reflects a lower amount of fluid in the bloodstream, which causes a reduced production of saliva. Once the hypothalamus detects such changes, it stimulates the release of ADH to signal the kidneys to reduce urine flow and return more water to the bloodstream. As previously discussed, the kidneys also secrete renin, which eventually results in the production of angiotensin II and the retention of water.Water is drawn out of the salivary glands in the mouth in an attempt to further dilute the concentration of substances in the blood; this causes the mouth and throat to become even drier. Together, these mechanisms prevent a further loss of body fluid and help avoid dehydration

Heat Stroke

A potentially fatal response to high temperature characterized by failure of the body's heatregulating mechanisms. Symptoms include rapid pulse, reduced sweating, hot and dry skin, high temperature, headache,weakness, and sudden loss of consciousness.Commonly called sunstroke Symptoms include rapid pulse; hot, dry skin; high temperature; and loss of consciousness. people who are active in a hot environment should stop exercising if they feel dizzy, light-headed, disoriented, or nauseated

Opsin

A protein that combines with retinal in the retina to form rhodopsin

Bleaching Process

A reaction in which the rod cells in the retina lose their color when rhodopsin is split into retinal and opsin.

Solvent

A substance that is capable of mixing with and breaking apart a variety of compounds.Water is an excellent solvent.

Seleniotmethionine

An amino acid derivative that is the storage form for selenium in the body.

Seleniocystiene

An amino acid derivative that is the active form of selenium in the body.

RECAP

Selenium is part of the glutathione peroxidase enzyme system.It indirectly spares vitamin E from oxidative damage, and it assists with immune function and the production of thyroid hormone. Organ meats, pork, and seafood are good sources of selenium, as are Brazil nuts. The selenium content of plants is dependent on the amount of selenium in the soil in which they are grown. Toxicity symptoms include brittle hair and nails, nausea, vomiting, and liver cirrhosis. Deficiency can result in Keshan disease,Kashin-Beck disease, impaired immune function, infertility, and muscle wasting.Copper, zinc, and manganese are cofactors for the superoxide dismutase antioxidant enzyme system. Iron is a cofactor for the catalase antioxidant enzyme. These minerals play critical roles in blood health and energy metabolism

Selenium Toxicity

Selenium toxicity does not result from eating foods high in selenium. However, supplementation can cause toxicity. Toxicity symptoms include brittle hair and nails that can eventually break and fall off. Other symptoms include skin rashes, nausea, vomiting, weakness, and cirrhosis of the liver

Food sources of Sodium

Sodium is found naturally in many common foods, and many processed foods contain large amounts of added sodium. Thus, it is easy to consume excess amounts in our daily diets

Functions of Vitamin C

Vitamin C is probably most well known for its role in preventing scurvy, a disease that ravaged sailors on long sea voyages centuries ago. In fact, the derivation of the term ascorbic acid means "a" (without) "scorbic" (having scurvy). Scurvy was characterized by bleeding tissues, especially of the gums, and is thought to have caused more than half of the deaths that occurred at sea. During these long voyages, the crew ate all of the fruits and vegetables early in the trip then had only grain and animal products available until they reached land to resupply. In 1740 in England, Dr. James Lind discovered that citrus fruits could prevent scurvy. This is due to their high vitamin C content. Fifty years after the discovery of the link between citrus fruits and prevention of scurvy, the British Navy finally required all ships to provide daily lemon juice rations for each sailor to prevent the onset of scurvy. A century later, sailors were given lime juice rations, earning them the nickname "limeys." It wasn't until 1930 that vitamin C was discovered and identified as a nutrient. One reason that vitamin C prevents scurvy is that it assists in the synthesis of collagen. Collagen, a protein, is a critical component of all connective tissues in the body, including bone, teeth, skin, tendons, and blood vessels. Collagen assists in preventing bruises, and it ensures proper wound healing, as it is a part of scar tissue and a component of the tissue that mends broken bones.Without adequate vitamin C, the body cannot form collagen, and tissue hemorrhage, or bleeding, occurs. Vitamin C may also be involved in the synthesis of other components of connective tissues, such as elastin and bone matrix. In addition to connective tissues, vitamin C assists in the synthesis of DNA, bile, neurotransmitters such as serotonin (which helps regulate mood), and carnitine, which transports long-chain fatty acids from the cytosol into the mitochondria for energy production. Vitamin C also helps ensure that appropriate levels of thyroxine, a hormone produced by the thyroid gland, are produced to support basal metabolic rate and to maintain body temperature. Other hormones that are synthesized with assistance from vitamin C include epinephrine, norepinephrine, and steroid hormones. Vitamin C also acts as an antioxidant. Because it is water soluble, it is an important antioxidant in the extracellular fluid. Like vitamin E, it donates electrons to free radicals, thus preventing the damage of cells and tissues (see Figure 10.5a). It also protects LDLcholesterol from oxidation, which may reduce the risk for cardiovascular disease.Vitamin C acts as an important antioxidant in the lungs, helping to protect us from the damage caused by ozone and cigarette smoke.1 It also enhances immune function by protecting the white blood cells from the oxidative damage that occurs in response to fighting illness and infection. But contrary to popular belief, it is not a miracle cure (see the accompanying Nutrition Myth or Fact? box on vitamin C). In the stomach, vitamin C reduces the formation of nitrosamines, cancer-causing agents found in foods such as cured and processed meats.We discuss the role of vitamin C and other antioxidants in preventing some forms of cancer later in this chapter (pages 383-384). Vitamin C also regenerates vitamin E after it has been oxidized. This occurs when ascorbic acid donates electrons to vitamin E radicals, becoming dehydroascorbic acid (Figure 10.6). The regenerated vitamin E can now continue to protect cell membranes and other tissues. In turn, dehydroascorbic acid is regenerated as an antioxidant by gaining an electron from the reduced form of glutathione (GSH), which is a tripeptide composed of glycine, cysteine, and glutamic acid. Glutathione is then restored to its antioxidant form by the enzyme glutathione reductase, in a reaction (not shown in Figure 10.6) that is dependent on the mineral selenium, which is discussed later in this chapter Vitamin C also enhances the absorption of iron. It is recommended that people with low iron stores consume vitamin C-rich foods along with iron sources to improve absorption. For people with high iron stores, this practice can be dangerous and lead to iron toxicity

Collagen

collagen A protein found in all connective tissues in the body.

Food Sources of Potassium

fresh foods, particularly fresh fruits and vegetables. identifies foods that are high in potassium. Processing foods generally increases their amount of sodium and decreases their amount of potassium. Thus, you can optimize your potassium intake and reduce your sodium intake by avoiding processed foods and eating more fresh fruits, vegetables, legumes, and whole grains

Glutathione

glutathione A tripeptide composed of glycine, cysteine, and glutamic acid that assists in regenerating vitamin C into its antioxidant form.

Definitions

hyperkeratosis A condition resulting in the excess accumulation of the protein keratin in the follicles of the skin; this condition can also impair the ability of epithelial tissues to produce mucus. xerophthalmia An irreversible blindness due to hardening of the cornea and drying of the mucous membranes of the eye.

Not enough Vitamin A

night blindness and color blindness can result from vitamin A deficiency. How severe a problem is night blindness? Although less common among people of developed nations, vitamin A deficiency is a severe public health concern in developing nations. According to the World Health Organization, approximately 250 million preschool children suffer from vitamin A deficiency.14 Of the children affected, 250,000 to 500,000 become permanently blinded every year. Death is due to infections and illnesses, including measles and diarrhea, that are easily treated in wealthier countries.Vitamin A deficiency is also a tragedy for pregnant women in these countries. These women suffer from night blindness, are more likely to transmit HIV to their child if HIV-positive, and run a greater risk of maternal mortality. Chapter 19 includes an in-depth discussion of what is being done to combat vitamin A deficiency and night blindness throughout the world. If vitamin A deficiency progresses, it can result in irreversible blindness due to hardening of the cornea (the transparent membrane covering the front of the eye), a condition called xerophthalmia. The prefix of this word, xero-, comes from a Greek word meaning "dry." Lack of vitamin A causes the epithelial cells of the cornea to lose their ability to produce mucus, causing the eye to become very dry. This leaves the cornea susceptible to damage, infection, and hardening. Once the cornea hardens in this way, the resulting blindness is irreversible. This is why it is critical to catch vitamin A deficiency in its early stages and treat it with either the regular consumption of fruits and vegetables that contain betacarotene or with vitamin A supplementation. Vitamin A deficiency can also lead to follicular hyperkeratosis, a condition characterized by the excess accumulation of the protein keratin in the hair follicles. Keratin is a protein that is usually only found on the outermost surface of skin, hair, nails, and tooth enamel.With hyperkeratosis, keratin clogs hair follicles, makes skin rough and bumpy, prevents proper sweating through the sweat glands, and causes skin to become very dry and thick. Hyperkeratosis can also affect the epithelial cells of various tissues, including the mouth, urinary tract, vagina, and eyes, reducing the production of mucus by these tissues and leading to an increased risk of infection. Hyperkeratosis can be reversed with vitamin A supplementation. Other deficiency symptoms include impaired immunity, increased risk of illness and infections, reproductive system disorders, and failure of normal growth. Individuals who are at risk for vitamin A deficiency include elderly people with poor diets, newborn or premature infants (due to low liver stores of vitamin A), young children with inadequate vegetable and fruit intakes, and alcoholics. Any condition that results in fat malabsorption can also lead to vitamin A deficiency. Children with cystic fibrosis; individuals with Crohn disease, celiac disease, and diseases of the liver, pancreas, or gallbladder; and people who consume large amounts of the fat substitute Olestra are at risk for vitamin A deficiency.

Alkalosis

pH above 7.45

Potassium

potassium is the major positively charged electrolyte in the intracellular fluid. It is a major constituent of all living cells and is found in both plants and animals. About 85% of dietary potassium is absorbed, and as with sodium, the kidneys regulate reabsorption and urinary excretion of potassium.

Proox

prooxidant, as you might guess, is a nutrient that promotes oxidation. I

Provitmain

provitamin An inactive form of a vitamin that the body can convert to an active form.An example is beta-carotene beta-carotene is not considered an essential nutrient, it is a provitamin found in many fruits and vegetables. Our bodies convert beta-carotene to an active form of vitamin A, or retinol; thus, beta-carotene is a precursor of retinol

Retinal

retinal An active, aldehyde form of vitamin A that plays an important role in healthy vision and immune function

Retinoic

retinoic acid An active, acid form of vitamin A that plays an important role in cell growth and immune function.

Retinol

retinol An active, alcohol form of vitamin A that plays an important role in healthy vision and immune function

Name the critical solutes in the body

the body fluids are a variety of dissolved substances (called solutes) critical to life. These include four major minerals: sodium, potassium, chloride, and phosphorus. these minerals in compounds called salts, including table salt, which is made of sodium and chloride

Definiations

tocopherols A family of vitamin E that is the active form in our bodies. tocotrienols A family of vitamin E that does not play an important biological role in our bodies. erythrocyte hemolysis The rupturing or breakdown of red blood cells, or erythrocytes

Oxidation

A chemical reaction in which molecules of a substance are broken down into their component atoms.During oxidation, the atoms involved lose electrons This loss of electrons is called oxidation, because it is fueled by oxygen. Atoms are also capable of gaining electrons, through a complementary process called reduction (Figure 10.1b). Because oxidation-reduction reactions typically result in an even exchange of electrons, scientists call them exchange reactions

HTN

A chronic condition characterized by above-average blood pressure readings; specifically, systolic blood pressure over 140 mm Hg or diastolic blood pressure over 90 mm Hg. Although hypertension itself is often without symptoms, it increases a person's risk for many other serious conditions, including heart disease, stroke, and kidney disease; it can also reduce brain function, impair physical mobility, and cause death. Blood pressure is measured in two phases: systolic and diastolic. Systolic blood pressure represents the pressure exerted in the arteries at the moment that the heart contracts, sending blood into the blood vessels. Diastolic blood pressure represents the pressure in the arteries between contractions, when the heart is relaxed. You can also think of diastolic blood pressure as the resistance in the arteries that the heart must pump against every time it beats. Blood pressure is measured in millimeters of mercury (mm Hg). When your blood pressure is measured, the systolic pressure is given first, followed by the diastolic pressure For about 90% to 95% of people who have it, the causes of hypertension are unknown. This type is referred to as primary or essential hypertension. For the other 5% to 10% of people with hypertension, causes may include kidney disease, sleep apnea (a sleep disorder that affects breathing), or chronic alcohol abuse

iodopsin

A color-sensitive pigment found in the cone cells of the retina

Antioxidant

A compound that has the ability to prevent or repair the damage caused by oxidation. Anti means "against," and antioxidants work against, or prevent oxidation.

Salt Resistance

A condition in which certain people do not experience changes in blood pressure with changes in salt intake.

Salt Sensitivity

A condition in which certain people respond to a high salt intake by experiencing an increase in blood pressure; these people also experience a decrease in blood pressure when salt intake is low.

hyperkalemia

A condition in which blood potassium levels are dangerously high. people with kidney disease are not able to regulate their blood potassium levels. Hyperkalemia, or high blood potassium concentration, occurs when potassium is not efficiently excreted from the body. Because of potassium's role in cardiac muscle contraction, severe hyperkalemia can alter the normal rhythm of the heart, resulting in heart attack and death. People with kidney disease must monitor their potassium intake very carefully, and should avoid consuming salt substitutes, as these products are high in potassium.

Hypokalemia

A condition in which blood potassium levels are dangerously low. Kidney disease, diabetic ketoacidosis, and other illnesses can lead to potassium deficiency. Extreme dehydration, vomiting, and diarrhea can also cause hypokalemia, as can longterm consumption of natural licorice, which contains glycyrrhizic acid (GZA), a substance that increases urinary excretion of potassium. Because the majority of foods that contain licorice flavoring in the United States do not contain GZA, licorice-induced hypokalemia is rarely seen here. People who abuse alcohol or laxatives can suffer from hypokalemia. Symptoms include confusion, loss of appetite, and muscle weakness. Severe cases of hypokalemia result in fatal changes in heart rate; many deaths attributed to extreme dehydration or an eating disorder are caused by abnormal heart rhythms due to hypokalemia

Hypernatremia

A condition in which blood sodium levels are dangerously high. refers to an abnormally high blood sodium concentration. It is usually caused by a rapid intake of high amounts of sodium, such as when a shipwrecked sailor drinks seawater. Eating a high-sodium diet does not usually cause hypernatremia in a healthy person, as the kidneys are able to excrete excess sodium in the urine. But people with congestive heart failure or kidney disease are not able to excrete sodium effectively, making them more prone to the condition. Hypernatremia is dangerous because it causes an abnormally high blood volume, leading to edema (swelling) of tissues and raising blood pressure to unhealthy levels

Hyponatremia

A condition in which blood sodium levels are dangerously low. abnormally low blood sodium concentration, can occur in active people who drink large volumes of water and fail to replace sodium. Severe diarrhea, vomiting, or excessive prolonged sweating can also cause hyponatremia. Symptoms of hyponatremia include headaches, dizziness, fatigue, nausea, vomiting, and muscle cramps. If hyponatremia is left untreated, it can lead to seizures, coma, and death. Treatment for hyponatremia includes the ingestion of liquids and foods high in sodium and may even require the administration of electrolyte-rich solutions intravenously if the person has lost consciousness or is not able to consume beverages and foods by mouth.

Vitamin A for eyesight

A critical role of vitamin A in the body is certainly in the maintenance of healthy vision. Specifically, vitamin A affects our sight in two ways: it enables us to react to changes in the brightness of light, and it enables us to distinguish between different wavelengths of light; in other words, to see different colors. Let's take a closer look at this process. Light enters the eyes through the cornea, travels through the lens, and then hits the retina, which is a delicate membrane lining the back of the inner eyeball retina, retinal combines with a protein called opsin to form rhodopsin, a light-sensitive pigment. Rhodopsin is found in the rod cells, which are cells that react to dim light and interpret black-and-white images. When light hits the retina, the rod cells go through a bleaching process. In this reaction, rhodopsin is split into retinal and opsin and the rod cells lose their color. The retinal component also changes spatial orientation from a cis configuration, which is bent, into a trans configuration, which is straight. The opsin component also changes shape. These changes in retinal and opsin during the bleaching process generate a nerve impulse that travels to the brain, resulting in the perception of a black-and-white image.Most of the retinal is converted back to its original cis form and binds with opsin to regenerate rhodopsin, allowing the visual cycle to begin again. However, some of the retinal is lost with each cycle and must be replaced by retinol from the bloodstream. This visual cycle goes on continually, allowing our eyes to adjust moment-to-moment to subtle changes in our surroundings or in the level of light. When levels of vitamin A are deficient, people suffer from a condition referred to as night blindness. Night blindness results in the inability of the eyes to adjust to dim light. It can also result in the failure to regain sight quickly after a bright flash of light (Figure 10.12). At the same time that we are interpreting black-and-white images, the cone cells of the retina, which are only effective in bright light, use retinal to interpret different wavelengths of light as different colors. The pigment involved in color vision is iodopsin. Iodopsin experiences similar changes during the color vision cycle as rhodopsin does during the blackand- white vision cycle. As with the rod cells, the cone cells can also be affected by a deficiency of vitamin A, resulting in color blindness

Cancer

A group of diseases characterized by cells that reproduce spontaneously and independently and may invade other tissues and organs is actually a group of diseases that are all characterized by cells that grow "out of control." By this we mean that cancer cells reproduce spontaneously and independently, and they are not inhibited by the boundaries of tissues and organs. Thus, they can aggressively invade tissues and organs far away from those in which they originally formed. Most forms of cancer result in one or more tumors, which are newly formed masses of undifferentiated cells that are immature and have no physiologic function. Although the word tumor sounds frightening, it is important to note that not every tumor is malignant, or cancerous.Many are benign (not harmful to us) and are made up of cells that will not spread widely.

RECAP

A healthy fluid level is maintained in the body by balancing intake with excretion.Primary sources of fluids include water and other beverages, foods, and the production of metabolic water in the body.Fluid losses occur through urination,sweating, the feces, and evaporation from the lungs

Keshan disease

A heart disorder caused by selenium deficiency. It was first identified in children in the Keshan province of China

Free Radical

A highly unstable atom with an unpaired electron in its outermost shell.

ADH

A hormone released from the pituitary gland in response to an increase in blood solute concentration. ADH stimulates the kidneys to reabsorb water and to reduce the production of urine

Rhodopsin

A light-sensitive pigment found in the rod cells that is formed by retinal and opsin.

Lazy and CAncer

A sedentary lifestyle increases the risk of colon cancer and may increase the risk for other forms of cancer.18 At the same time, a recent review of several studies has found that moderately intense and vigorous physical activity are associated with a 20% to 30% reduction in our overall risk for cancer.21 A clear protective effect of exercise was found specifically for breast and colon cancers. At this time, we do not know how exercise reduces the overall risk for cancer or for certain types of cancers. However, these findings have prompted the American Cancer Society and the National Cancer Institute to promote increased physical activity as a way to reduce our risk for cancer.

Reactive Oxygen Spe

A specific term used to describe an oxygen molecule that has become a free radical. a free radical will "steal" an electron from stable compounds, in turn generating more unstable free radicals. This is a dangerous chain reaction, because the free radicals generated can damage or destroy cells

Fluid

A substance composed of molecules that move past one another freely. Fluids are characterized by their ability to conform to the shape of whatever container holds them.

Electrolytes

A substance that disassociates in solution into positively and negatively charged ions and is thus capable of carrying an electrical current. because when they dissolve in water, the two component minerals separate and form electrically charged particles called ions. This electrical charge, which can be positive or negative, is the "spark" that stimulates nerves and causes muscles to contract, making electrolytes critical to body function.

Diuretic

A substance that increases fluid loss via the urine.Common diuretics include alcohol as well as prescription medications for high blood pressure and other disorders.

night Blindness

A vitamin A-deficiency disorder that results in loss of the ability to see in dim light

What are some water soluble materials and non-water soluble materials that the body transports

All water-soluble substances—such as amino acids, glucose, the water-soluble vitamins, minerals, and some medications—are readily transported via the bloodstream. In contrast, fats do not dissolve in water. To overcome this chemical incompatibility, fatty substances such as lipids and the fat-soluble vitamins are either attached to or surrounded by water-soluble proteins so they, too, can be transported in the blood to the cells.

Renin

An enzyme secreted by the kidneys in response to a decrease in blood pressure. Renin converts the blood protein angiotensinogen to angiotensin I, which eventually results in an increase in sodium reabsorption. Renin then activates a blood protein called angiotensinogen, which is produced in the liver. Angiotensinogen is the precursor of another blood protein, angiotensin I

Angiotensin II

Angiotensin I is converted to angiotensin II, which is a powerful vasoconstrictor; this means it works to constrict the diameter of blood vessels, which results in an increase in blood pressure

Aldosterone

Angiotensin II also signals the release of the hormone aldosterone from the adrenal glands. Aldosterone signals the kidneys to retain sodium and chloride. Because water travels with these two minerals, this results in water retention, which increases blood pressure and decreases urine output A hormone released from the adrenal glands that signals the kidneys to retain sodium and chloride, which in turn results in the retention of water.

Vitamin Contributes to cell differentiation

Another important role of vitamin A is its contribution to cell differentiation, the process by which stem cells mature into highly specialized cells that perform unique functions. The retinoic acid form of vitamin A interacts with the receptor sites on a cell's DNA. This interaction influences gene expression and the determination of the type of cells that the stem cells eventually become. Obviously, this process is critical to the development of healthy organs and effectively functioning body systems. An example of cell differentiation is the development of epithelial cells such as skin cells and mucus-producing cells of the protective linings of the lungs, vagina, intestines, stomach, bladder, urinary tract, and eyes. The mucus that epithelial cells produce lubricates the tissue and helps to propel microbes, dust particles, foods, and fluids out of the body tissues (for example, when we cough up secretions or empty the bladder).When vitamin A levels are insufficient, the epithelial cells fail to differentiate appropriately and we lose these protective barriers against infectious microbes and irritants. Vitamin A is also critical to the differentiation of specialized immune cells called T-lymphocytes, or T-cells. T-cells assist in fighting infections. You can therefore see why vitamin A deficiency can lead to a breakdown of immune responses and to infections and other disorders of the lungs and respiratory tract, urinary tract, vagina, and eyes.

How do antioxidants work in the body

Antioxidant vitamins, minerals, and other compounds accomplish these functions in a variety of ways: 1. Antioxidant vitamins work independently by donating their electrons or hydrogen molecules to free radicals to stabilize them and reduce the damage caused by oxidation Antioxidant minerals, including selenium, copper, iron, zinc, and manganese, act as cofactors within complex antioxidant enzyme systems that convert free radicals to less damaging substances that are excreted by the body. They also work to break down fatty acids that have become oxidized, thereby destroying the free radicals associated with them. Antioxidant enzyme systems also make more vitamin antioxidants available to fight other free radicals. Examples of antioxidant enzyme systems include the following: • Superoxide dismutase converts free radicals to less damaging substances, such as hydrogen peroxide. • Catalase removes hydrogen peroxide from the body by converting it to water and oxygen. • Glutathione peroxidase also removes hydrogen peroxide from the body and stops the production of free radicals in lipids. 3. Other compounds such as beta-carotene and other phytochemicals help stabilize free radicals and prevent damage to cells and tissues. In summary, free-radical formation is generally kept safely under control by certain vitamins, minerals working within antioxidant systems, and phytochemicals. Next, we take a look at the specific vitamins and minerals involved.

Ion

Any electrically charged particle, either positively or negatively charged

Neuromuscular d/o

Because nerves synapse with muscles, electrolyte imbalances that alter nervous system function will in turn disturb muscle function. For example, seizures are uncontrollable muscle spasms that may be localized to one area of the body, such as the face, or can violently wrack a person's entire body. Muscle cramps are involuntary, spasmodic, and painful muscle contractions that last for many seconds or even minutes. Hypernatremia that occurs with dehydration is known to cause cramps, as are other electrolyte imbalances.Muscle weakness and paralysis can also occur with severe electrolyte imbalances such as hypokalemia, hyperkalemia, and low blood phosphorus levels.

Consumption of too much Vitamin C

Because vitamin C is water soluble, we usually excrete any excess. Consuming excess amounts in food sources does not lead to toxicity, and only supplements can lead to toxic doses. Taking megadoses of vitamin C is not fatally harmful. However, side effects of doses exceeding 2,000 mg per day for a prolonged period include nausea, diarrhea, nosebleeds, and abdominal cramps. There are rare instances in which consuming even moderately excessive doses of vitamin C can be harmful. As mentioned earlier, vitamin C enhances the absorption of iron. This action is beneficial to people who need to increase iron absorption. It can be harmful, however, to people with a disease called hemochromatosis, which causes an excess accumulation of iron in the body. Such iron toxicity can damage tissues and lead to a heart attack. In people who have preexisting kidney disease, taking excess vitamin C can lead to the formation of kidney stones. This does not appear to occur in healthy individuals. Critics of vitamin C supplementation claim that taking the supplemental form of the vitamin is "unbalanced" nutrition and leads vitamin C to act as a prooxidant

Functions of Beta Carotene

Beta-carotene and some other carotenoids are nutrients recognized to have antioxidant properties. 8 Like vitamin E, they are fat-soluble and fight the harmful effects of oxidation in the lipid portions of the cell membranes and in LDLs; but, compared with vitamin E, beta-carotene is a relatively weak antioxidant. In fact, other carotenoids, such as lycopene and lutein, may be stronger antioxidants than beta-carotene. Research is currently being conducted to elucidate how many carotenoids are found in foods and which ones are effective antioxidants. Carotenoids play other important roles in the body through their antioxidant actions. Specifically, they: • Enhance the immune system and boost the body's ability to fight illness and disease. • Protect skin from the damage caused by the sun's ultraviolet rays. • Protect our eyes, preventing or delaying age-related vision impairment. Carotenoids are also associated with a decreased risk of certain types of cancer

RECAP

Beta-carotene is a carotenoid and a provitamin of vitamin A. It protects the lipid portions of cell membranes and LDL-cholesterol from oxidative damage.It also enhances immune function and protects vision.There is no RDA for beta-carotene.Orange, red, and deep-green fruits and vegetables are good sources of beta-carotene. There are no known toxicity or deficiency symptoms, but yellowing of the skin can occur if too much beta-carotene is consumed.

How much fluid is in the human body

Between about 50% and 70% of a healthy adult's body weight is fluid.When we cut a finger, we can see some of this fluid dripping out as blood, but the fluid in the bloodstream can't account for such a large percentage of one's total body weight

Blood volume

Blood volume is the amount of fluid in blood; thus, appropriate body fluid levels are essential to maintaining healthful blood volume.When blood volume rises inappropriately, blood pressure increases; when blood volume decreases inappropriately, blood pressure decreases. kidneys play a central role in the regulation of blood volume and blood pressure. While filtering the blood, they reabsorb (retain) water and other nutrients that the body needs and excrete waste products and excess water in the urine. Changes in blood volume, blood pressure, and concentration of solutes in the blood signal the kidneys to adjust the volume and concentration of urine.

RECAP

Body fluid consists of water plus a variety of dissolved substances, including electrically charged minerals called electrolytes. Water serves many important functions, including dissolving and transporting substances, accounting for blood volume, regulating body temperature, and cushioning and lubricating body tissues

How much do body fluids vary

Body fluid levels also vary according to gender and age.Males have more lean tissue and thus a higher percentage of body weight as fluid than females. The amount of body fluid as a percentage of total weight decreases with age. About 75% of an infant's body weight is water, whereas the total body water of an elderly person is generally less than 50% of body weight. This decrease in total body water is, in part, a result of the loss of lean tissue that can occur as people age

Types of water that we can consume

Carbonated water contains carbon dioxide gas that either occurs naturally or is added to the water.Mineral water contains 250 to 500 parts per million (ppm) of minerals.Many people prefer the unique taste of mineral water; however, a number of brands contain high amounts of sodium and so should be avoided by people who are trying to reduce their sodium intake. Distilled water is processed in such a way that all dissolved minerals are removed; this type of water is often used in steam irons, as it will not clog the iron with mineral build-up, but it has a flat taste. Purified water has been treated so that all dissolved minerals and contaminants are removed, making this type of water useful in research and medical procedures. Of course, we can also drink the tap water found in our homes and in public places.

Cells are permeable

Cells cannot voluntarily regulate this flow of water and thus have no active control over the balance of fluid between the intracellular and extracellular compartments. membranes are not freely permeable to electrolytes. Sodium, potassium, and the other electrolytes stay where they are, either inside or outside of a cell, unless they are actively transported elsewhere by special proteins.

Chloride

Chloride is a negatively charged ion that is obtained almost exclusively from sodium chloride or table salt. It should not be confused with chlorine, which is a poisonous gas used to kill germs in our water supply. As with sodium, the majority of dietary chloride is absorbed in the small intestine. The kidneys regulate urinary excretion of chloride

RECAP

Chloride is the major negatively charged electrolyte outside of the cell. It assists with fluid balance, digestion, immune responses, and the transmission of nerve impulses. The AI for chloride is 2.3 g per day.Our main dietary source of chloride is sodium chloride. There is no known toxicity for chloride alone. Chloride deficiencies are rare but can occur during severe dehydration and frequent vomiting

Diet and Cancer

Consumption of substances such as alcohol, dietary fat, and compounds found in cured and charbroiled meats can increase the risk for cancer (see Highlight on page 384). Nutritional factors that are protective against cancer include antioxidants, fiber, and phytochemicals (discussed In Depth on pages 389-407). Diets high in saturated fats and low in fruits and vegetables increase the risk of cancers of the esophagus, colon, breast, and prostate.18 Increasing your intake of whole grains, fruits, and vegetables, decreasing your intake of red meats and fatty meats, and maintaining a healthy weight are keys to cancer prevention.

Functions of Cl

Coupled with sodium in the extracellular fluid, chloride assists with the maintenance of fluid balance. Chloride is also a part of hydrochloric acid (HCl) in the stomach, which aids in preparing food for further digestion (see Chapter 3). Chloride also works with the white blood cells during an immune response to help kill bacteria, and it assists in the transmission of nerve impulses

What happens if we don't drink enough water

Dehydration results when we do not drink enough water or are unable to retain the water we drink. It is one of the leading causes of death around the world. Because an understanding of the physiology of dehydration requires familiarity with the roles and requirements for the major electrolytes, we discuss this condition, along with a related illness called heat stroke

RECAP

Dehydration, heat stroke, and even death can occur when water loss exceeds water intake. Because the thirst mechanism is not always sufficient, it is important to drink water throughout the day to promote adequate fluid intake.Hypertension is a major chronic illness in the United States; it can often be controlled by losing weight if overweight, increasing physical activity,decreasing alcohol intake,and making specific dietary changes such as those in the DASH diet. Electrolyte imbalances can also lead to neuromuscular disorders. Intake of sugary beverages can contribute to obesity

Dehyd

Depletion of body fluid that results when fluid excretion exceeds fluid intake. occur as a result of heavy exercise or exposure to high environmental temperatures, when the body loses significant amounts of water through increased sweating and breathing. However, elderly people and infants can get dehydrated even when inactive, as their risk for dehydration is much higher than that of healthy young and middle-aged adults. The elderly are at increased risk because they have a lower total amount of body water and their thirst mechanism is less effective than that of a younger person; they are therefore less likely to meet their fluid needs. Infants, on the other hand, excrete urine at a higher rate, cannot tell us when they are thirsty, and have a greater ratio of body surface area to body core, causing them to respond more dramatically to heat and cold and to lose more body water than an older child relatively small losses in body water result in symptoms such as thirst, discomfort, and loss of appetite.More severe water losses result in symptoms that include sleepiness, nausea, flushed skin, and problems with mental concentration. Severe losses of body water can result in delirium, coma, cardiac arrest, and death.

Overhydration

Dilution of body fluid. It results when water intake or retention is excessive. water intoxication, can occur but it is rare. It generally only occurs in people with health problems that cause the kidneys to retain too much water, causing overhydration and hyponatremia,

What happens if we drink too much water

Drinking too much water and becoming overhydrated is very rare. Even individuals who regularly consume large quantities of water do not develop major health problems because healthy kidneys are able to process the excess water. Certain illnesses can cause excessive reabsorption or retention of water by the kidneys. When this occurs, overhydration and dilution of blood sodium result. Also, as described in the introductory story on Cynthia Lucero, marathon runners and other endurance athletes can overhydrate and dangerously dilute their serum sodium concentration. This condition, called hyponatremia,

RECAP

Electrolytes help regulate fluid balance by controlling the movement of fluid into and out of cells. Electrolytes, specifically sodium and potassium, play a key role in generating nerve impulses in response to stimuli. Calcium is an electrolyte that stimulates muscle contraction.

XU

Even when a person consumes a low-sodium diet, chloride intake is usually adequate. A chloride deficiency can occur, however, during conditions of severe dehydration and frequent vomiting. This is sometimes seen in people with eating disorders who regularly vomit to rid their bodies of unwanted energy

Conversion forms of Vitamin E

For conversion purposes: • In food, 1α-TE is equal to 1 mg of active vitamin E. • In supplements containing natural sources of vitamin E, 1 IU is equal to 0.67 mg α-TE. • In supplements containing synthetic sources of vitamin E, 1 IU is equal to 0.45 mg α-TE.

RECAP

Free radicals are formed when a stable atom loses or gains an electron and this electron remains unpaired.They can be produced during the formation of ATP, when our immune system fights infections,and when we are exposed to radiation or toxic substances. Free radicals can damage our cell membranes, low-density lipoproteins (LDLs), cell proteins, and DNA and are associated with many chronic diseases, including heart disease, various cancers, and diabetes. Antioxidant vitamins donate electrons or hydrogen atoms to free radicals to stabilize them. Antioxidant minerals function as part of antioxidant enzyme systems that convert free radicals to less damaging substances. Some phytochemicals also have antioxidant properties.

Food sources of Vit. C

Fruits and vegetables are the best sources of vitamin C. Because heat and oxygen destroy vitamin C, fresh sources of these foods have the highest content. Cooking foods, especially boiling them, leaches their vitamin C, which is then lost when we strain them. Forms of cooking that are least likely to compromise the vitamin C content of foods include steaming, microwaving, and stir-frying. As indicated in Figure 10.7, many fruits and vegetables are high in vitamin C. Citrus fruits (such as oranges, lemons, and limes), potatoes, strawberries, tomatoes, kiwi fruit, broccoli, spinach and other leafy greens, cabbage, green and red peppers, and cauliflower are excellent sources of vitamin C. Fortified beverages and cereals are also good sources. Dairy foods, meats, and nonfortified cereals and grains provide little or no vitamin C. By eating the recommended amounts of fruits and vegetables daily, we can easily meet the body's requirement for vitamin C. Remember that a serving of vegetables is 1/2 cup of cooked or 1 cup of raw vegetables or 6 oz of vegetable juice, and a serving of fruit is one medium fruit, 1 cup of chopped or canned fruit, or 6 oz of fruit juice.

What is Na linked to?

HTN. Sodium is necessary for survival

Heredity and Cancer

Heredity can play a role in the development of cancer, because inherited "cancer genes," such as the BRC genes for breast cancer, increase the risk that an individual with those genes will develop cancer. However, it is important to bear in mind that a family history of cancer does not guarantee you will get cancer, too. It just means that you are at an increased risk and should take all preventive actions available to you.While some risk factors are out of your control, others are modifiable, which means that you can take positive steps to reduce your risk

What happens when we eat a diet in high sodium

High blood pressure is more common in people who consume high-sodium diets. This strong relationship has prompted many health organizations to recommend lowering sodium intakes. Consuming excessive sodium has been shown to cause increased urinary excretion of calcium in some people, which in turn may increase the risk for bone loss

Infection and Cancer

Infectious agents account for 18% of cancers worldwide. For example, infection of the female cervix with the sexually transmitted virus Human papillomavirus is linked to cervical cancer (Figure 10.20), and infection with the bacterium Helicobacter pylori is linked not only to ulcers but also to stomach cancer. As microbial research advances, it is thought that more cancers will be linked to infectious agents

Rod CElls

Light-sensitive cells found in the retina that contain rhodopsin and react to dim light and interpret black-and-white images.

Cone CElls

Light-sensitive cells found in the retina that contain the pigment iodopsin and react to bright light and interpret color images

Vitamin A as an AOX

Limited research indicates that vitamin A may act as an antioxidant.12, 13 Like vitamins E and C, it appears to scavenge free radicals and protect LDLs from oxidation. As you might expect, adequate vitamin A levels in the blood are associated with lower risks of some forms of cancer and heart disease. However, the role of vitamin A as an antioxidant is not strongly established and is still under investigation.

Not all Beverages are created equal

Milk: provides calcium, phosphorus, vitamin D and Vitamin A. Specialized include calcium, vitamin E, EFAS, plant sterols,. Kefir, calcium fortified soy milk provide proteins and vitamin D. Rice milk is low in protein Hot Beverages: Coffee without cream is healthy. caffeine doesn't significantly decrease the bods hydration status. Coffee can lower the risk of TIIDM, lower stroke risk. Tea: Camellia sinesis/black tea is the most processed tea, oolong tea is partially fermented. white tea made from the buds, green tea and white tea leave are dried but not fermented and have higher phytocheimcals than oolong tea. phytochemicals are thought to reduce LDL and increase HDL. camellian sinesis provides caffeine and related stimulants. Chocolate and cocoa: theobromine, similar effects to caffeine and presnt in lower amounts. Soft drinks: loaded with sugar. switching from HFCS to pure sugar. "pure fruit concentrate"is more pure than sugar iwth none of the fiber or nutrients. . Energy drinks: contain 3x the amount of caffiene comparable to cola. has guarana seed extrate with more caffeine. Taurine is an AA associated with mm contractions. increases blood pressure and heart rate. mood swings, behavioral d/d, insomina, dizziness, tremors, sz, caffeine dependency, dehydration have been linked to energy drinks. caffeine OD is common in people younger than 19 yo. sounce of added sugar. Desginer waters: nutrients in these waters are soo low that they rarely make an impact on peoples health. Sportsbeverages/coconut water:

Vitamin A facts

More important, vitamin A is critical to vision and the growth and differentiation of cells. There are three active forms of vitamin A in the body: retinol is the alcohol form, retinal is the aldehyde form, and retinoic acid is the acid form. These three forms are collectively referred to as the retinoids (Figure 10.10). Of the three, retinol has the starring role in maintaining the body's physiologic functions. Remember from the previous section that beta-carotene is a precursor to vitamin A: The beta-carotene in foods is converted to retinol in the wall of the small intestine. Preformed vitamin A is present in foods in the form of retinol and also as retinyl ester-compounds, in which retinol is attached to a fatty acid. These retinyl ester-compounds are hydrolyzed in the small intestine, leaving retinol in its free form. Free retinol is then absorbed into the wall of the small intestine, where a fatty acid is attached to form new retinyl ester-compounds. These compounds are then packaged into chylomicrons and enter into the lymph system. The chylomicrons transport vitamin A to the cells as needed or into the liver for storage. About 90% of the vitamin A we absorb is stored in the liver; the remainder is stored in adipose tissue, the kidneys, and the lungs Retinol-binding protein is one such carrier protein for vitamin A. Retinol-binding protein carries retinol from the liver to the cells that require it. The unit of expression for vitamin A is Retinol Activity Equivalents (RAE). You may still see the expression Retinol Equivalents (RE) or International Units (IU) for vitamin A on food labels or dietary supplements. The conversions to RAE from various forms of retinol and from the units IU and RE are as follows: • 1 RAE 1 microgram (μg) retinol • 1 RAE 12 μg beta-carotene • 1 RAE 24 μg alpha-carotene or beta-cryptoxanthin • 1 RAE 1 RE • 1 RAE 3.3 IU

Tabacco Use and CAncer

More than 40 compounds in tobacco and tobacco smoke are carcinogens, or substances that can cause cancer. Using tobacco increases the risk for cancers of the lung, larynx, mouth, and esophagus and can also cause heart disease, stroke, and emphysema (Figure 10.18). (See the Highlight box on disorders linked to tobacco use, page 382.) The positive news is that tobacco use is a modifiable risk factor. If you smoke or use smokeless tobacco, you can reduce your risk for cancer considerably by quitting

What nutrients keep us hydrated

Nutrients that assist in maintaining hydration and neuromuscular function include water and the minerals sodium, potassium, chloride, and phosphorus. Major nutrients in the body: Nutrient Recommended Intake Sodium 1.5 g/day* Potassium 4.7 g/day * Chloride 2.3 g/day* Phosphorus 700 mg/day†

How much Beta-Carotene should we consume

Nutritional scientists do not consider beta-carotene and other carotenoids to be essential nutrients, as they play no known essential roles in our body and are not associated with any deficiency symptoms. Thus, no RDA for these compounds has been established. It has been suggested that consuming 6 to 10 mg of beta-carotene per day from food sources can increase the beta-carotene levels in the blood to amounts that may reduce the risks for some diseases, such as cancer and heart disease.8 Supplements containing beta-carotene have become very popular, and supplementation studies have prescribed doses of 15 to 30 mg of beta-carotene. Refer to the accompanying Nutrition Myth or Fact? box on beta-carotene to learn more about how supplementation with this compound may affect the risk for cancer. Fruits and vegetables that are red, orange, yellow, and deep green are generally high in beta-carotene and other carotenoids such as lutein and lycopene. Eating the recommended amounts of fruits and vegetables each day ensures an adequate intake of carotenoids. Because of its color, beta-carotene is used as a natural coloring agent for many foods, including margarine, yellow cheddar cheese, cereal, cake mixes, gelatins, and soft drinks. However, these foods are not significant sources of beta-carotene. Figure 10.9 identifies common foods that are high in beta-carotene. We generally absorb only between 20% and 40% of the carotenoids present in the foods we eat. In contrast to vitamins E and C, carotenoids are absorbed better from cooked foods. Carotenoids are bound in the cells of plants, and the process of lightly cooking these plants breaks chemical bonds and can rupture cell walls, which humans don't digest. These actions result in more of the carotenoids being released from the plant. For instance, 1 cup of raw carrots contains approximately 9 mg of beta-carotene, whereas the same amount of cooked frozen carrots contains approximately 12 mg

What if we don't consume enough vitamin E

One vitamin E deficiency symptom is erythrocyte hemolysis. This rupturing of red blood cells leads to anemia, a condition in which the red blood cells cannot carry and transport enough oxygen to the tissues, leading to fatigue, weakness, and a diminished ability to perform physical and mental work.We discuss anemia in more detail in Chapter 12. Premature babies can suffer from vitamin E-deficiency anemia; if born too early, the infant does not receive vitamin E from its mother, as the transfer of this vitamin from mother to baby occurs during the last few weeks of the pregnancy. Other symptoms of vitamin E deficiency include loss of muscle coordination and reflexes, leading to impairments in vision, speech, and movement. As you might expect, vitamin E deficiency can also impair immune function, especially if accompanied by low body stores of the mineral selenium. In adults, vitamin E deficiencies are usually caused by diseases, particularly diseases that cause malabsorption of fat, such as those that affect the small intestine, liver, gallbladder, and pancreas. As reviewed in Chapter 3, the liver makes bile, which is necessary for the absorption of fat. The gallbladder delivers the bile into our intestines, where it facilitates digestion of fat. The pancreas makes fat-digesting enzymes. Thus, when the liver, gallbladder, or pancreas are not functioning properly, fat and the fat-soluble vitamins, including vitamin E, cannot be absorbed, leading to their deficiency.

Osmosis

Osmosis. (a) A filter that is freely permeable to water is placed in a glass of pure water. (b) Salt is added to only one side of the glass. (c) Drawn by the high concentration of electrolytes, pure water flows to the "salt water" side of the filter.This flow of water into the concentrated solution will continue until the concentration of electrolytes on both sides of the membrane is equal The answer is that water always moves from areas where solutes such as sodium and chloride are in low concentrations to areas where they are highly concentrated. This movement is referred to as osmosis. To put it another way, electrolytes attract water toward areas where they are concentrated. This movement of water toward solutes continues until the concentration of solutes is equal on both sides of the cell membrane. Water follows the movement of electrolytes; this action provides a means to control movement of water into and out of the cells

Too much phosphorus

People suffering from kidney disease and people taking too many vitamin D supplements or too many phosphorus-containing antacids can suffer from high blood phosphorus levels. Severely high levels of blood phosphorus cause muscle spasms and convulsions

Phosphorus

Phosphorus is the major intracellular negatively charged electrolyte. In the body, phosphorus is most commonly found combined with oxygen in the form of phosphate, PO4 -3. Phosphorus is an essential constituent of all cells and is found in both plants and animals. Adults absorb about 55% to 70% of dietary phosphorus, primarily in the small intestine. The active form of vitamin D (1,25-dihydroxyvitamin D or calcitriol) facilitates the absorption of phosphorus, whereas consumption of aluminum-containing antacids and high doses of calcium carbonate reduce its absorption. The kidneys regulate reabsorption and urinary excretion of phosphorus

RECAP

Phosphorus is the major negatively charged electrolyte inside of the cell. It helps maintain fluid balance and bone health.It also assists in making energy available and in regulating chemical reactions, and it is a primary component of genetic materials. The RDA for phosphorus is 700 mg per day, and it is commonly found in high-protein foods.Excess phosphorus can lead to muscle spasms and convulsions, and phosphorus deficiencies are rare.

Functions of Phosphorus

Phosphorus works with potassium inside of the cell to maintain proper fluid balance. It also plays a critical role in bone formation, as it is a part of the mineral complex of bone (see Chapter 11). In fact, about 85% of the body's phosphorus is stored in the bones. primary component of ATP, phosphorus plays a key role in creating energy for the body through the reactions in glycolysis and oxidative phosphorylation. It also helps regulate many biochemical reactions by activating and deactivating enzymes during phosphorylation. Phosphorus is a part of both DNA and RNA, and it is a component of cell membranes (as phospholipids) and of lipoproteins

What are the functions of potassium

Potassium and sodium work together to maintain proper fluid balance and to regulate the contraction of muscles and transmission of nerve impulses. Potassium also assists in maintaining blood pressure. In contrast with a high-sodium diet, eating a diet high in potassium actually helps maintain a lower blood pressure.

RECAP

Potassium is the major positively charged electrolyte inside of the cell. It regulates fluid balance,blood pressure,and muscle contraction, and it helps in the transmission of nerve impulses.The AI for potassium is 4.7 g per day. Potassium is found in abundance in fresh foods, particularly fruits and vegetables. Both hyperkalemia and hypokalemia can result in heart failure and death.

Blood Buffers:

Proteins -- having ability to take up excess hydrogen ions during acidosis and ability to release hydrogen ions when the blood becomes to basic. Bicarbonate-carbonic acid system: CO2, one of the end products of energy metabolism dissolves in the blood stream to form carbonic acid which itself dissociated into hydrogen and bicarb. (reversible reaction). Respiratory compensation -- fast acting, blood buffers don't have enough buffering capacity to correct large and long-term-acid-base imbalances. increasing and decreasing rate of respiration. Renal compensation -- lungs to regulate acid-base balance is limited. kidneys can excrete or secrete into the blood significant biocarbonate to correct A-B balance. Can also use non-bicarbonate buffers such as ammonia or hydrogen phosphate to excrete hydrogen ions.

CVD and AOX

Remember that the major risks for CVD are smoking, hypertension (high blood pressure), high blood levels of LDL-cholesterol, obesity, and a sedentary lifestyle. Other risk factors include a low level of high-density lipoprotein (HDL) cholesterol, diabetes, family history (CVD in males younger than 55 years of age and females younger than 65 years of age), being a male older than 45 years of age, and being a postmenopausal woman. Although we cannot alter our gender, family history, or age, we can change our nutrition and physical activity habits to reduce our risk for CVD. Research has recently identified a risk factor for CVD that may be even more important than elevated cholesterol levels. This risk factor is a condition called low-grade inflammation. 30 This condition weakens the plaque in the blood vessels, making it more fragile. You may remember from Chapter 5 that plaque is the fatty material that builds up on the lining of arteries and causes atherosclerosis. As the plaque becomes more fragile, it is more likely to burst, breaking away from the arterial lining and traveling freely in the bloodstream. It may then lodge in the blood vessels of the heart or brain, closing them off and leading to a heart attack or stroke, respectively In laboratory blood tests, the marker that indicates the degree of inflammation is C-reactive protein. Having higher levels of C-reactive protein increases the risk for a heart attack even if people do not have elevated cholesterol levels. For people with high levels of C-reactive protein and cholesterol, the risk of a heart attack is almost nine times higher than that of someone with normal cholesterol and C-reactive protein levels. These findings have prompted the medical community to develop standards for measuring C-reactive protein along with cholesterol as a test for CVD risk. How can antioxidants decrease the risk for CVD? There is growing evidence that certain antioxidants, specifically vitamin E and lycopene, work in a variety of ways that reduce the damage to the vessels, which in turn reduces the risk for a heart attack or stroke. Some of the ways these nutrients decrease the risk for CVD include scavenging free radicals, reducing low-grade inflammation, and reducing blood coagulation and the formation of blood clots. As with the research conducted on cancer, the studies of antioxidants and CVD show inconsistent results. Two large-scale surveys conducted in the United States show that men and women who eat more fruits and vegetables have a significantly reduced risk of CVD.31, 32 However, few intervention studies have been conducted to determine the effect of antioxidant supplements on risk for CVD.Vitamin E was found to lower the number of heart disease deaths in smokers in the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study, but had no overall effect on the risk of stroke.33 In the HOPE study, vitamin E had no impact on the risk for CVD in people who are at high risk for heart attack and stroke.3 Recently published results of large intervention studies in the United States indicate no reductions in major cardiovascular events in men and women taking vitamins E or C.4, 28 Thus, there is growing evidence that antioxidant supplements do not reduce our risk for CVD. It is important to note that other compounds (besides antioxidants) found in fruits, vegetables, and whole grains can reduce our risk for CVD. For instance, soluble fiber has been shown to reduce elevated LDL-cholesterol and total cholesterol. The most successful effects have been found in people eating oatmeal and oat-bran cereals. Dietary fiber in general has been shown to reduce blood pressure, lower total cholesterol levels, and improve blood glucose and insulin levels. Folate, a B-vitamin, is found in fortified cereals, green leafy vegetables, bananas, legumes, and orange juice. Folate is known to reduce homocysteine levels in the blood, and a high concentration of homocysteine in the blood is a known risk factor for CVD. A recent study from the Netherlands showed that individuals who drank more than three cups of black tea (which is high in flavonoids) per day had a lower rate of heart attacks than non-tea drinkers.34 Thus, it appears that there are a plethora of nutrients and other components in fruits, vegetables, and whole-grain foods that may be protective against CVD.

UV and CAncer

Skin cancer is the most common form of cancer in the United States and accounts for over half of all cancers diagnosed each year.Most cases of skin cancer are linked to exposure to ultraviolet (UV) rays from the sun and indoor tanning beds. UV rays damage the DNA of immature skin cells, which then reproduce uncontrollably. Research has shown that a person's risk for skin cancer doubles if he or she has had five or more sunburns; however, your risk for skin cancer still increases with UV exposure even if you do not get sunburned.19 Exposure to tanning beds before age 35 increases by 75% your risk of developing the most invasive form of skin cancer.20 Skin cancer includes the nonmelanoma cancers (basal cell and squamous cell cancers), which are not typically invasive, and malignant melanoma, which is one of the most deadly of all types of cancer (Figure 10.21). Limiting exposure to sunlight to no more than 20 minutes between 10 AM and 4 PM can help reduce your risk for skin cancer while allowing your body to synthesize adequate vitamin D. After that, wear sunscreen with at least a 15 SPF (sun protection factor) rating and protective clothing.

RECAP

Sodium is the primary positively charged electrolyte in the extracellular fluid. It works to maintain fluid balance and blood pressure, assists in acid-base balance and transmission of nerve signals, aids muscle contraction, and assists in the absorption of some nutrients. The AI for sodium is 1.5 g per day.Deficiencies are rare, because the typical American diet is high in sodium. Excessive sodium intake has been related to high blood pressure and loss of bone density in some, but not all, studies.

DASH

Term for the Dietary Approach to Stop Hypertension, this diet plan emphasizes fruits and vegetables, whole grains, low/no-fat milk and dairy, and lean meats. This plan is similar to the goals of MyPyramid in that it is low in fat and high in fiber. The DASH diet also emphasizes foods that are rich in potassium, calcium, and magnesium, including 10 servings of fruits and vegetables each day along with whole-grain foods and low-fat or nonfat milk and dairy products. The sodium content of the DASH diet is about 3 g (or 3,000 mg) of sodium, which is slightly less than the average sodium intake in the United States. Over the past several years, many research studies have convincingly illustrated that eating the DASH diet has a positive impact on blood pressure. Decreases in blood pressure can occur within the first 2 weeks of following it. Researchers estimated that if all Americans followed the DASH diet plan, heart disease would be reduced by 15% and the number of strokes would be 27% lower. Another study of the DASH diet has found that blood pressure continues to decrease if sodium intake is reduced below 3,000 mg per day.20 Participants ate a DASH diet that provided either 3,300 mg (average U.S. intake), 2,400 mg (upper recommended intake), or 1,500 mg of sodium each day. After 1 month on this diet, all people eating the DASH diet saw a significant decrease in their blood pressure; These results indicate that eating a diet low in sodium and high in fruits and vegetables reduces blood pressure and decreases the risk for heart disease and stroke. In addition to its beneficial effects in reducing blood pressure, the DASH diet has also been shown to lower risk for coronary heart disease and stroke among women23 as well as the risk for metabolic syndrome.24 Finally, the DASH diet has been shown to be particularly beneficial in hypertensive African Americans, a population group at very high risk for the disease and its complications.

How much Cl should we consume

The AI for chloride for adult men and women aged 19 to 50 years is 2.3 g/day (or 2,300 mg/day

What is the recommended amount of sodium we should consume

The AI for sodium is 1.5g/day (or 1,500 mg/day) for adult men and women aged 19 to 50 years half a teaspoon of salt.4 The AI drops to 1.3 g/day for those 51 to 70 years of age and 1.2 g/d for persons over the age of 70 years.Most people in the United States greatly exceed this guideline, consuming between 3 and 6 g of sodium per day.Most health organizations recommend a daily sodium intake of no more than 2.3 g per day, and the 2005 Dietary Guidelines specifically recommend that African Americans (who have a higher risk of hypertension) and persons with hypertension limit their daily sodium intake to no more than 1.5g

how much of phosphorus to consume and food sources

The RDA for phosphorus is 700 mg per day.16 The average U.S. adult consumes about twice this amount each day, thus phosphorus deficiencies are rare. Phosphorus is widespread in many foods and is found in high amounts in foods that contain protein.Milk, meats, and eggs are good sources of phosphorus (Figure 9.10). It is important to note that phosphorus from animal sources is absorbed more readily than phosphorus from plant sources.Much of the phosphorus in plant foods such as beans, whole-grain cereals, and nuts is found in the form of phytic acid, a plant storage form of phosphorus. Our bodies do not produce enzymes that can break down phytic acid, but we are still able to absorb up to 50% of the phosphorus found in plant foods because the bacteria in the large intestine can break down phytic acid. Soft drinks are another common source of phosphorus in the die

RDA for Vitamin A

The RDA for vitamin A is 900 μg per day for men and 700 μg per day for women. The UL is 3,000 μg per day of preformed vitamin A in women (including those pregnant and lactating) and men.

RDA for Vitamin C

The RDA for vitamin C is 90 mg per day for men and 75 mg per day for women. The Tolerable Upper Intake Level (UL) is 2,000 mg per day for adults. Smoking increases a person's need for vitamin C. Thus, the RDA for smokers is 35 mg more per day than for nonsmokers. This equals 125 mg per day for men and 110 mg per day for women. Other situations that may increase the need for vitamin C include healing from a traumatic injury, surgery, or burns and the use of oral contraceptives among women; there is no consensus as to how much extra vitamin C is needed in these circumstances

How much Vitamin E should we consume?

The RDA for vitamin E for men and women is 15 mg alpha-tocopherol per day. This is the amount determined to be sufficient to prevent erythrocyte hemolysis, or the rupturing (lysis) of red blood cells (erythrocytes). The tolerable upper intake level (UL) is 1,000 mg alpha-tocopherol per day. Remember that one of the primary roles of vitamin E is to protect PUFAs from oxidation. Thus, our need for vitamin E increases as we eat more oils and other foods that contain PUFAs. Fortunately, these foods also contain vitamin E, so we typically consume enough vitamin E within them to protect their PUFAs from oxidation.

How does fluid help protect and lubricate our tissues

The cerebrospinal fluid that surrounds the brain and spinal column protects these vital tissues from damage, and a fetus in a mother's womb is protected by amniotic fluid. Synovial fluid lubricates joints, and tears cleanse and lubricate the eyes. Saliva moistens the food we eat, and the mucus lining the walls of the GI tract helps it move smoothly along. Finally, the pleural fluid covering the lungs allows their friction-free expansion and retraction behind the chest wall

Directions of Osmosis depending on Electrolytes

The concentration of electrolytes is the same on either side of the cell membrane. (b) The concentration of electrolytes is much greater inside the cell, drawing water into the cell and making it swell. (c) The concentration of electrolytes is much greater outside the cell, drawing water out of the cell and making it shrink. Certain illnesses can threaten the delicate balance of fluid inside and outside of the cells. You may have heard of someone being hospitalized because of excessive diarrhea and vomiting. When this happens, the body loses a great deal of fluid from the intestinal tract and extracellular compartment. This heavy fluid loss causes the extracellular electrolyte concentration to become very high. In response, a great deal of intracellular fluid leaves the cells to try to balance this extracellular fluid loss. This imbalance in fluid and electrolytes changes the flow of electrical impulses through the heart, causing an irregular heart rate that can be fatal if left untreated. Food poisoning and eating disorders involving repeated vomiting and diarrhea can also result in death from life-threatening fluid and electrolyte imbalances

How much selenium do we need and food sources

The content of selenium in foods is highly variable. As it is a trace mineral, we need only minute amounts to maintain health. The RDA for selenium is 55 μg per day for both men and women. The UL is 400 μg per day. Selenium is present in both plant and animal food sources but in variable amounts. Because it is stored in the tissues of animals, selenium is found in reliably consistent amounts in animal foods. Organ meats, such as liver and kidney, as well as pork and seafood, are particularly good sources

Intracellular Fluid

The fluid held at any given time within the walls of the body's cells. About two-thirds of the body's fluid is held within the walls of cells

Intravascular Fluid

The fluid in the bloodstream and lymph.

Extracellular Fluid

The fluid outside of the body's cells, either in the body's tissues (interstitial fluid) or as the liquid portion of the blood or lymph (intravascular fluid). There are two types of extracellular fluid: 1. Interstitial fluid flows between the cells that make up a particular tissue or organ, such as muscle fibers or the liver. 2. Intravascular fluid is the water in the bloodstream and lymph. Plasma is specifically the extracellular fluid portion of blood that transports blood cells within the body's arteries, veins, and capillaries Not every tissue in the body contains the same amount of fluid. Lean tissues, such as muscle, are more than 70% fluid, whereas fat tissue is only between 10% and 20% fluid.

interstitial Fluid

The fluid that flows between the cells that make up a particular tissue or organ, such as muscle fibers or the liver.

Obesity

The introduction of a very cheap sweetener, high-fructose corn syrup, and dramatic changes in the marketing and sales of beverages led to a surge in the popularity of sodas and other sweetened drinks. Today, Americans take in approximately 21% of their calories from beverages, mostly in the form of sweetened soft drinks and fruit juices. Recently, sweetened bottled waters, bottled teas, and specialty coffee drinks have contributed to the problem: a coffee mocha at one national chain provides 400 calories, which is 20% of an average adult's total daily calorie needs. It's not surprising, then, that researchers believe that calories from these types of sweetened beverages have contributed to half of the rise in caloric intake among Americans since the late 1970s—and thus are factors in our current obesity epidemic. Beverages with a high calorie content do little to curb appetite, so most people do not compensate for the extra calories they drink by eating less. In addition, sweetened sodas, teas, and other specialty beverages displace more nutritious beverages such as milk, which provides protein, calcium, vitamin D, and other nutrients important for bone health

Insensible Water Loss

The loss of water not noticeable by a person, such as through evaporation from the skin and exhalation from the lungs during breathing. insensible water loss is less than 1 liter (L) of fluid each day; during heavy exercise or in hot weather, a person can lose up to 2 L of water per hour from insensible water loss. Under normal conditions, only about 150 to 200 ml of water is lost each day in the feces. The gastrointestinal tract typically reabsorbs much of the large amounts of fluids that pass through it each day. five avenues of regular fluid loss, certain situations can cause a significant loss of fluid from the body: • Illnesses that involve fever, coughing, vomiting, diarrhea, and a runny nose significantly increase fluid loss. This is why doctors advise people to drink plenty of fluids when they are ill. • Traumatic injury, internal hemorrhaging, blood donation, and surgery also increase loss of fluid because of the blood loss involved. • Exercise increases fluid loss via sweat and respiration; although urine production typically decreases during exercise, fluid losses increase through the skin and lungs. • Environmental conditions that increase fluid loss include high altitudes, cold and hot temperatures, and low humidity such as in a desert or on an airplane. Because the water content of these environments is low, water from the body readily evaporates into the atmosphere.We also breathe faster at higher altitudes due to the lower oxygen pressure; this results in greater fluid loss via the lungs.We sweat more in the heat, thus losing more water. Cold temperatures can trigger hormonal changes that result in an increased fluid loss. • Pregnancy increases fluid loss for the mother because fluids are continually diverted to the fetus and amniotic fluid. • Breastfeeding requires a tremendous increase in fluid intake to make up for the loss of fluid. • Consumption of diuretics—substances that increase fluid loss via the urine—can result in dangerously excessive fluid loss. Diuretics include certain prescription medications and alcohol.Many over-the-counter weight-loss remedies are really just diuretics. In the past, it was believed that the caffeine in beverages such as coffee, tea, and cola could cause serious dehydration, but recent research suggests that caffeinated drinks do not have a significant impact on the hydration status of adults

Food sources of Vitamin A

The most common sources of dietary preformed vitamin A are animal foods such as beef liver, chicken liver, eggs, and whole-fat dairy products.Vitamin A is also found in fortified reduced-fat milks, margarine, and some breakfast cereals (Figure 10.13). The other half of the vitamin A we consume comes from foods high in beta-carotene and other carotenoids that can be converted to vitamin A. green, orange, and deep-yellow fruits and vegetables are good sources of beta-carotene and thus of vitamin A. Carrots, spinach, mango, cantaloupe, and tomato juice are excellent sources of vitamin A because they contain beta-carotene

How much water should we drink

The need for water varies greatly depending on age, body size, health status, physical activity level, and exposure to environmental conditions The DRI for adult men aged 19 to 50 years is 3.7 L of total water per day. This includes approximately 3.0 L (or 13 cups) as total water, other beverages, and food.4 The DRI for adult women aged 19 to 50 is 2.7 L of total water per day. This includes about 2.2 (or 9 cups) as total water, other beverages, and food.

Osmotic Pressure

The pressure that is needed to keep the particles in a solution from drawing liquid toward them across a semipermeable membrane. Cells can regulate the osmotic pressure, and thus the balance of fluids between their internal and extracellular environments, by using special transport proteins to actively pump electrolytes across their membranes.

What are the functions of Vitamin E

The primary function of vitamin E is as an antioxidant: It donates an electron to free radicals, stabilizing them and preventing them from destabilizing other molecules. Once vitamin E is oxidized, it is either excreted from the body or recycled back into active vitamin E through the help of other antioxidant nutrients, such as vitamin C. Because vitamin E is prevalent in adipose tissue and cell membranes, its action specifically protects polyunsaturated fatty acids (PUFAs) and other fatty components of our cells and cell membranes from being oxidized (see Figure 10.2b).Vitamin E also protects LDLs from being oxidized, thereby lowering the risk for heart disease.1, 2 (The relationship between antioxidants and heart disease is reviewed later in this chapter.) In addition to protecting PUFAs and LDLs, vitamin E protects the membranes of red blood cells from oxidation and plays a critical role in protecting the cells of our lungs, which are constantly exposed to oxygen and the potentially damaging effects of oxidation.Vitamin E's role in protecting PUFAs and other fatty components also explains why it is added to many oilbased foods and skincare products—by preventing oxidation in these products, it reduces rancidity and spoilage. Vitamin E serves many other roles essential to human health. It is critical for normal fetal and early childhood development of nerves and muscles, as well as for maintenance of their functions. It enhances immune function by protecting white blood cells and other components of the immune system, thereby helping the body to defend against illness and disease. It also improves the absorption of vitamin A

RECAP Vitamin A

The role of vitamin A as an antioxidant is still under investigation.Vitamin A is critical for maintaining our vision. It is also necessary for cell differentiation, reproduction, and growth.The RDA for vitamin A is 900 μg per day for men and 700 μg per day for women. Animal liver, dairy products, and eggs are good animal sources of vitamin A; fruits and vegetables are high in beta-carotene, which is used to synthesize vitamin A. Supplementation can be dangerous, as toxicity is reached at levels of only three to four times the RDA. Toxicity symptoms include birth defects, spontaneous abortion, blurred vision, and liver damage.Deficiency symptoms include night blindness, impaired immune function, and growth failure

Metabolic Water

The water formed as a by-product of the body's metabolic reactions. In the breakdown of fat, carbohydrate, and protein, adenosine triphosphate (ATP), carbon dioxide, and water are produced. The water that is formed during metabolic reactions contributes about 10% to 14% of the water the body needs each day The fluid needed each day is obtained from three primary sources: beverages, foods, and the production of metabolic water by the body. Of course you know that beverages are mostly water, but it isn't as easy to see the water content in foods

Not enough Beta-CArotene

There are no known deficiency symptoms of beta-carotene or other carotenoids apart from beta-carotene's function as a precursor for vitamin A.

Cancer Progression

There are three primary steps of cancer development: initiation, promotion, and progression. These steps occur as follows: 1. Initiation: The initiation of cancer occurs when a cell's DNA is mutated (or changed). This mutation causes permanent changes in the cell. 2. Promotion: During this phase, the genetically altered cell is stimulated to repeatedly divide. The mutated DNA is locked into each new cell's genetic instructions. Because the enzymes that normally work to repair damaged cells cannot detect alterations in the DNA, the cells can continue to divide uninhibited. 3. Progression: During this phase, the cancerous cells grow out of control and invade surrounding tissues. These cells then metastasize (spread) to other sites of the body. In the early stages of progression, the immune system can sometimes detect these cancerous cells and destroy them. However, if the cells continue to grow, they develop into malignant tumors, and cancer results.

Sodium

Virtually all of the dietary sodium consumed is absorbed by the body.Most dietary sodium is absorbed from the small intestine, although some can be absorbed in the large intestine. As discussed earlier in this chapter, the kidneys reabsorb sodium when it needs to be retained by the body and excrete excess sodium in the urine

eating too much vitamin A

Vitamin A is highly toxic, and toxicity symptoms develop after consuming only three to four times the RDA. Toxicity rarely results from food sources, but vitamin A supplements are known to have caused severe illness and even death. Consuming excess vitamin A while pregnant can cause serious birth defects and spontaneous abortion. Other toxicity symptoms include fatigue, loss of appetite, blurred vision, hair loss, skin disorders, bone and joint pain, abdominal pain, nausea, diarrhea, and damage to the liver and nervous system. If caught in time, many of these symptoms are reversible once vitamin A supplementation is stopped. However, permanent damage can occur to the liver, eyes, and other organs. Because liver contains such a high amount of vitamin A, children and pregnant women should not consume liver on a daily or weekly basis.

Vitamin A is involved with reproduction

Vitamin A is involved in reproduction. Although its exact role is unclear, it appears necessary for sperm production in men and for fertilization to occur in women. It also contributes to healthy bone growth by assisting in breaking down old bone so that new, longer, and stronger bone can develop. As a result of a vitamin A deficiency, children suffer from stunted growth and wasting. Two popular treatments for acne contain derivatives of vitamin A. Retin-A, or tretinoin, is a treatment applied to the skin. Accutane, or isotretinoin, is taken orally. These medications should be used carefully and only under the supervision of a licensed physician. Both medications increase a person's sensitivity to the sun, and it is recommended that exposure to sunlight be limited while using them. They also can cause birth defects in infants if used while a woman is pregnant and can lead to other toxicity problems, depression, and suicide in some individuals. Interestingly, vitamin A itself has no effect on acne; thus, vitamin A supplements are not recommended in its treatment

Not enough Vitamin C

Vitamin C deficiencies are rare in developed countries but can occur in developing countries. Scurvy is the most common vitamin C-deficiency disease. The symptoms of scurvy appear after about 1 month of a vitamin C-deficient diet. Symptoms include bleeding gums and joints, loose teeth, weakness, hemorrhages around the hair follicles of the arms and legs, wounds that fail to heal, swollen ankles and wrists, bone pain and fractures, diarrhea, and depression. Anemia can also result from vitamin C deficiency. People most at risk of deficiencies include those who eat few fruits and vegetables, including impoverished or homebound individuals, and people who abuse alcohol and drugs

RECAP Vitamin C

Vitamin C scavenges free radicals and regenerates vitamin E after it has been oxidized. Vitamin C prevents scurvy and assists in the synthesis of collagen, hormones, neurotransmitters,and DNA.Vitamin C also enhances iron absorption.The RDA for vitamin C is 90 mg per day for men and 75 mg per day for women.Many fruits and vegetables are high in vitamin C. Toxicity is uncommon with dietary intake; symptoms include nausea, diarrhea, and nosebleeds.Deficiency symptoms include scurvy, anemia, diarrhea, and depression.

Vitamin E

Vitamin E is one of the fat-soluble vitamins; thus, dietary fats carry it from the intestines through the lymph system and eventually transport it to the cells.Vitamin E is absorbed with dietary fat and incorporated into the chylomicrons. As the chylomicrons are broken down, most of the vitamin E remains in their remnants and is transported to the liver. There, vitamin E is incorporated into very-low-density lipoproteins (VLDLs) and released into the blood. As described in Chapter 5, VLDLs are transport vehicles that ferry triglycerides from their source to the body's cells. After VLDLs release their triglyceride load, they become LDLs.Vitamin E is a part of both VLDLs and LDLs and is transported to the tissues and cells by both of these lipoproteins Vitamin E and the other fat-soluble vitamins are stored in the body. The liver serves as a storage site for vitamins A and D, and about 90% of the vitamin E in the body is stored in our adipose tissue. The remaining vitamin E is found in cell membranes.

What are food sources of Vitamin E

Vitamin E is widespread in foods.Much of the vitamin E that we consume comes from vegetable oils and the products made from them (Figure 10.4). Safflower oil, sunflower oil, canola oil, and soybean oil are good sources. Mayonnaise and salad dressings made from these oils also contain vitamin E. Nuts, seeds, and some vegetables also contribute vitamin E to our diet. Although no single fruit or vegetable contains very high amounts of vitamin E, eating the recommended amounts of fruits and vegetables each day will help ensure adequate intake of this nutrient. Cereals are often fortified with vitamin E, and other grain products contribute modest amounts to our diet.Wheat germ and soybeans are also good sources of vitamin E. Animal and dairy products are poor sources. Vitamin E is destroyed by exposure to oxygen, metals, ultraviolet light, and heat. Although raw (uncooked) vegetable oils contain vitamin E, heating these oils destroys vitamin E. Thus, foods that are deep-fried and processed contain little vitamin E. This includes most fast foods and convenience foods

RECAP

Vitamin E protects cell membranes from oxidation, enhances immune function, and improves the absorption of vitamin A if dietary intake is low.The RDA for vitamin E is 15 mg alpha-tocopherol per day for men and women.Vitamin E is found primarily in vegetable oils and nuts.Toxicity is uncommon, but taking very high doses can cause excessive bleeding. A genuine deficiency is rare, but symptoms include anemia and impaired vision, speech, and movement

Sensible Water Loss

Water loss that is noticed by a person, such as through urine output and sweating. Most of the water we consume is excreted through the kidneys in the form of urine.When we consume more water than we need, the kidneys process and excrete it in the form of dilute urine. The second type of sensible water loss is via sweat. The sweat glands produce more sweat during exercise or when a person is in a hot environment. The evaporation of sweat from the skin releases heat, which cools the skin and reduces the body's core temperature

how much potassium do we need to consume

We can reduce our risk for high blood pressure by consuming adequate potassium in our diet. The AI for potassium for adult men and women aged 19 to 50 years is 4.7 g/day (or 4,700 mg/day

Function of Selenium

a heart disorder called Keshan disease and selenium deficiency. This disease occurs in children in the Keshan province of China, where the soil is depleted of selenium. The scientists found that Keshan disease can be prevented with selenium supplementation. The selenium in our bodies is contained in amino acids. Two amino acid derivatives contain the majority of selenium in our bodies: selenomethionine is the storage form for selenium, and selenocysteine is the active form of selenium. Selenocysteine is a critical component of the glutathione peroxidase enzyme system mentioned earlier (page 360). As shown in Figure 10.14, glutathione peroxidase breaks down the peroxides (such as hydrogen peroxide) that are formed by the body so they cannot form free radicals; this decrease in the number of free radicals spares vitamin E. Thus, selenium and vitamin E work together to prevent oxidative damage to lipids and decrease damage to cell membranes. Like vitamin C, selenium is needed for the production of thyroxine, or thyroid hormone. By this action, selenium is involved in the maintenance of basal metabolism and body temperature. Selenium appears to play a role in immune function, and poor selenium status is associated with higher rates of some forms of cancer

Describe how fluids maintain our temperature

a high internal temperature can cause the body to stop functioning. Fluids are vital to the body's ability to maintain its temperature within a safe range. Two factors account for the cooling power of fluids. First, water has a high capacity for heat: it takes a lot of energy to raise its temperature. Because the body contains a lot of water, only sustained high heat can increase body temperature. Second, body fluids are our primary coolant.When heat needs to be released from the body, there is an increase in the flow of blood from the warm body core to the vessels lying just under the skin. This action transports heat out to the body periphery, where it can be released from the skin.When we are hot, the sweat glands secrete more sweat from the skin. As this sweat evaporates off of the skin's surface, heat is released and the skin and underlying blood are cooled (Figure 9.3). This cooler blood flows back to the body's core and reduces internal body temperature.

What happens if we eat too much Vitamin E

adults 55 years of age or older with vascular disease or diabetes, a daily intake of 268 mg of vitamin E per day (about 18 times the RDA) for approximately 7 years resulted in a significant increase in heart failure. 3 However, these results have not been confirmed by additional research studies. At this time, it is unclear whether these adverse effects are an anomaly or if high supplemental doses of vitamin E may be harmful for certain individuals. Some individuals report side effects such as nausea, intestinal distress, and diarrhea with vitamin E supplementation. In addition, certain medications interact negatively with vitamin E. The most important of these are the anticoagulants, substances that stop blood from clotting excessively. Aspirin is an anticoagulant, as is the prescription drug Coumadin. Vitamin E supplements can augment the action of these substances, causing uncontrollable bleeding. In addition, new evidence suggests that in some people, long-term use of standard vitamin E supplements may cause hemorrhaging in the brain, leading to a type of stroke called hemorrhagic stroke

AOX supplements and cancer

antioxidant supplements and reducing cancer risk is not clear. Laboratory animal and test tube studies show that the individual nutrients reviewed in this chapter act as antioxidants in various situations. However, supplementation studies in humans do not consistently show benefits of taking antioxidant supplements in the prevention of cancer and other diseases. For example: • In the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study discussed earlier, supplementation with vitamin E resulted in a lower risk for cancers of the prostate, colon, and rectum but was related to more cancers of the stomach.9 In this same study, beta-carotene supplements increased risk for cancers of the lung, prostate, and stomach in current and former smokers.23 • In the Nutritional Prevention of Cancer Trial, selenium supplementation was found to reduce the risk of prostate, colon, and lung cancers, but it did not reduce the risk of nonmelanoma skin cancers.24 • The Linxian intervention trials, named for the region of China where the studies were conducted, found that a supplement containing beta-carotene, vitamin E, and selenium reduced mortality from overall cancer, specifically reducing the risk for cancers of the esophagus and stomach.25 • More recent trials such as the Physician's Health Study II,26 the SELECT trial,27 and the Women's Health Study28 have shown that taking vitamin C, vitamin E, and selenium supplements does not reduce the risk for total cancer or the risk for many site-specific cancers such as prostate, breast, colo-rectal, and lung. it is speculated that taking AOX supplements can taken in supplemental form may act as prooxidants in some situations, whereas antioxidants consumed in foods may be more balanced.Many studies currently being conducted are examining the impact of whole foods and antioxidant supplements on the risk for various forms of cancer

Acidosis

below 7.35

Can the body make antioxidants? What Vitamins and Minerals help with AOX status

body cannot form antioxidants spontaneously. Instead, we must consume them in our diet.Nutrients that appear to have antioxidant properties or are part of our protective antioxidant enzyme systems include vitamins E, C, and A; beta-carotene (a precursor to vitamin A); and the mineral selenium (see Table 1, page 362). The minerals copper, iron, zinc, and manganese play a peripheral role in fighting oxidation

How much water do Americans drink per year and why?

bottled water.7 Americans now consume about 28 gallons of bottled water per person, per year. This meteoric rise in bottled water production and consumption is most likely due to the convenience of drinking bottled water, to the health messages related to drinking more water, and to the public's fears related to the safety of tap water. Recent environmental concerns related to disposal of water bottles, however, has blunted the use of bottled water.8

Carotenoids

carotenoids Fat-soluble plant pigments that the body stores in the liver and adipose tissues.The body is able to convert certain carotenoids to vitamin A Beta-carotene is a phytochemical classified as a carotenoid, one of a group of plant pigments that are the basis for the red, orange, and deep-yellow colors of many fruits and vegetables. (Even dark-green leafy vegetables contain plenty of carotenoids, but the green pigment, chlorophyll, masks their color!) Although there are more than 600 carotenoids found in nature, only about 50 are found in the typical human diet. The six most common carotenoids found in human blood are alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein, lycopene, and zeaxanthin. Of these, the body can convert only alpha-carotene, betacarotene, and beta-cryptoxanthin to retinol. These are referred to as provitamin A carotenoids. One molecule of beta-carotene can be split to form two molecules of active vitamin A. Sometimes a beta-carotene molecule is cleaved in such a way that only one molecule of vitamin A is produced. In addition, not all of the dietary beta-carotene that is consumed is converted to vitamin A, and the absorption of beta-carotene from the intestines is not as efficient as our absorption of vitamin A. Nutritionists express the units of beta-carotene in a food as Retinol Activity Equivalents, or RAE. This measurement indicates how much active vitamin A is available to the body after it has converted the beta-carotene in the food

Too little phosphorus

deficiencies of phosphorus are rare. People who may suffer from low blood phosphorus levels include premature infants, elderly people with poor diets, and people who abuse alcohol. People with vitamin D deficiency, hyperparathyroidism (oversecretion of parathyroid hormone), and those who overuse antacids that bind with phosphorus may also have low blood phosphorus levels

Nerve Conduction and Action Potential

electrolytes are critical in enabling nerves to respond to stimuli. Nerve impulses are initiated at the membrane of a nerve cell in response to a change in the degree of electrical charge across the membrane. An influx of sodium into a nerve cell causes the cell to become slightly less negatively charged. This is called depolarization. If enough sodium enters the cell, the change in electrical charge triggers an action potential, an electrical signal that is then propagated along the length of the cell. Once the signal is transmitted, that portion of cell membrane returns to its normal electrical state through the release of potassium to the outside of the cell. This return of the cell to its initial electrical state is termed repolarization. Thus, both sodium and potassium play critical roles in ensuring that nerve impulses are generated, transmitted, and completed Simply stated,muscles are stimulated to contract in response to stimulation of nerve cells. As described earlier, sodium and potassium play a key role in the generation of nerve impulses, or electrical signals.When a muscle fiber is stimulated by an electrical signal, changes occur in the cell membrane that lead to an increased flow of calcium into the muscle from the extracellular fluid. This release of calcium into the muscle stimulates muscle contraction. The muscles can relax after a contraction once the electrical signal is complete and calcium has been pumped out of the muscle cell

What are the functions of Sodium

it is the major positively charged electrolyte in the extracellular fluid. Its exchange with potassium across cell membranes allows cells to maintain proper fluid balance; it also helps regulate blood pressure and acid-base balance. Sodium also assists with the transmission of nerve signals and aids in muscle contraction and relaxation. Finally, sodium assists in the absorption of glucose from the small intestine. Glucose is absorbed via active transport that involves sodium-dependent glucose transporters.

Where does a free radical damage the most?

most significant sites of free-radical damage is the cell membrane free radicals that form within the phospholipid bilayer of cell membranes steal electrons from their stable lipid molecules.When the lipid molecules, which are hydrophobic, are destroyed, they no longer repel water.With the cell membrane's integrity lost, the ability to regulate the movement of fluids and nutrients into and out of the cell is also lost. This loss of cell integrity causes damage to the cell and to all systems affected by this cell. Other sites of free-radical damage include low-density lipoproteins (LDLs), cell proteins, and DNA. Damage to these sites disrupts the transport of substances into and out of cells, alters protein function, and can disrupt cell function because of defective DNA. These changes may increase our risk for chronic diseases such as heart disease, various cancers, diabetes, cataracts, Alzheimer's disease, and Parkinson disease.

Selenium deficiency

selenium deficiency is associated with a form of heart disease called Keshan disease. Selenium deficiency does not cause the disease, but selenium is necessary to help the immune system effectively fight the viral infection or exposure to chemicals that prompt it.6 Selenium supplements significantly reduce the incidence of Keshan disease, but they cannot reduce the damage to the heart muscle once it occurs. Another deficiency disease is Kashin-Beck disease, a disease of the cartilage that results in deforming arthritis (Figure 10.16). Kashin-Beck disease is also found in selenium-depleted areas in China and in Tibet.Other deficiency symptoms include impaired immune responses, infertility, depression, impaired cognitive function, and muscle pain and wasting of both selenium and iodine in pregnant women can cause a form of cretinism in the infant

HOw much beta-carotene is too much

skin can turn yellow or orange if you consume large amounts of foods that are high in beta-carotene. This condition is referred to as carotenosis or carotenodermia, and it appears to be both reversible and harmless. Taking beta-carotene supplements is not generally recommended, because we can get adequate amounts of this nutrient by eating more fruits and vegetables

What do the four charged ions in the body and cells do

sodium (Na+) and potassium (K+) are positively charged, whereas chloride (Cl-) and phosphorus (in the form of hydrogen phosphate, or HPO4 2-) are negatively charged. In the intracellular fluid, potassium and phosphate are the predominant electrolytes. In the extracellular fluid, sodium and chloride predominate. There is a slight difference in electrical charge on either side of the cell's membrane that is needed in order for the cell to perform its normal functions.

What is the most active form of Vitamin e?

the most active, or potent, vitamin E compound found in food and supplements is alpha-tocopherol

Lifestyles changes to help HTN

there are five primary lifestyle changes that can help reduce it. These changes include: • Losing weight. Systolic blood pressure values have been shown to decrease 5 to 20 points in people who were overweight or obese and lost an average of 22 lb of body weight.19 • Increasing physical activity. The amount and intensity of exercise needed to improve blood pressure are easily achievable for most people. Regular physical activity, such as brisk walking, lasting at least 30 minutes per day, most days of the week, can help lower blood pressure.19 • Reducing alcohol intake. Because alcohol consumption can worsen high blood pressure, it is suggested that people with this disease abstain from drinking alcohol or limit their intake to no more than one (women) or two (men) drinks per day.19 • Reducing sodium intake in salt-sensitive individuals. Some people who are not salt sensitive also benefit from eating lower-sodium diets.19, 20 • Eating more whole grains, fruits, vegetables, and low-fat dairy foods

Cu, Fe, Zn, Mang. assist in AOX function

there are numerous antioxidant enzyme systems in our bodies. Copper, zinc, and manganese are a part of the superoxide dismutase enzyme complex. Iron is part of the structure of catalase. In addition to their role in protecting against oxidative damage, these minerals play major roles in the optimal functioning of many other enzymes in the body. Copper, iron, and zinc help maintain the health of our blood, and manganese is an important cofactor in carbohydrate metabolism. The functions, requirements, food sources, and deficiency and toxicity symptoms of these nutrients are discussed in detail in Chapter 12, which focuses on the nutrients involved in blood health and immunity

TOXICITY

there is no known toxicity symptom for chloride alone

What are the forms of Vitamin E

tocotrienols and tocopherols. None of the four different tocotrienol compounds—alpha, beta, gamma, and delta—appears to play an active role in the body. The tocopherol compounds are the biologically active forms. Four different tocopherol compounds have been discovered; as with tocotrienol, these have been designated alpha, beta, gamma, and delta

Selenium

trace mineral, and it is found in varying amounts in soil and thus in the food grown there. Keep in mind that although we need only minute amounts of trace minerals, they are just as important to our health as the vitamins and the major minerals. Selenium is efficiently absorbed, with about 50% to 90% of dietary selenium absorbed from the small intestine.6

Examples of diseases that cause acidosis and alkalosis

uncontrolled diabetes: acidosis vomiting/diarrhea: alkalosis

Vitamin C

water-soluble vitamin.We must therefore consume it on a regular basis, as any excess is excreted (primarily in the urine) rather than stored. There are two active forms of vitamin C: ascorbic acid and dehydroascorbic acid most animals can make their own vitamin C from glucose. Humans and guinea pigs are two groups that cannot synthesize their own vitamin C and must consume it in the diet. At low concentrations, vitamin C is absorbed in the intestines via active transport; at high concentrations, it is absorbed via simple diffusion. Between consumptions of 30 to 80 mg/day, about 70% to 90% of dietary vitamin C is absorbed, but absorption falls to less than 50% when more than 1 g per day is consumed.6 The kidneys regulate excretion of vitamin C, with increased excretion occurring during periods of high dietary intake and decreased excretion when dietary intakes are low.

Dehydration and Urine

you are properly hydrated, your urine should be clear to pale yellow in color, similar to diluted lemonade. Urine that is medium to dark yellow in color, similar to apple juice, indicates an inadequate fluid intake.Very dark or brown-colored urine, such as the color of a cola beverage, is a sign of severe dehydration and indicates potential muscle breakdown and kidney damage. People should strive to maintain a urine color that is clear or pale yellow.

How do AOX prevent cancer

• Enhancing the immune system, which assists in the destruction and removal of precancerous cells from the body • Inhibiting the growth of cancer cells and tumors • Preventing oxidative damage to the cells' DNA by scavenging free radicals and stopping the formation and subsequent chain reaction of oxidized molecules Eating whole foods that are high in antioxidants—especially fruits, vegetables, and whole grains—is consistently shown to be associated with decreased cancer risk.22 In addition, populations eating diets low in antioxidant nutrients have a higher risk for cancer. important interactions between antioxidant nutrients and other substances in foods, such as fiber and phytochemicals, which work together to reduce the risk for many types of cancers. Studies are now being conducted to determine whether eating foods high in antioxidants directly causes lower rates of cancer.