Nutr Exam 2

Hypertension

A healthy blood pressure is less than 120/80 mm Hg. Blood pressure from 120/80 to 129/80 mm Hg is referred to as elevated, and blood pressure that is consistently 130/80 mm Hg or greater indicates hypertension. Hypertension affects almost half of adults in the United States. Essential hypertension has no obvious external cause. The risk of developing high blood pressure is increased by a family history of hypertension, aging, obesity, diabetes, and lifestyle factors such as a lack of physical activity, heavy alcohol consumption, smoking, stress, and a poor diet. Diets high in sodium and low in potassium, magnesium, and calcium are associated with an increased risk of hypertension. The DASH diet—a dietary pattern moderate in sodium, high in potassium, magnesium, calcium, and fiber. and low in fat, saturated fat, and cholesterol—lowers blood pressure. Blood pressure management also involves maintenance of a healthy weight, an active lifestyle, and a limit on alcohol consumption.

What Is Aging?

Aging is the accumulation of changes over time that results in an ever-increasing susceptibility to disease and death. The longest an organism can live, or life span, is a characteristic of a species. The average age to which people in a population live, or life expectancy, is a characteristic of a population. As a population, we are living longer but not necessarily healthier lives. Older adults are the fastest-growing segment of the U.S. population. Compression of morbidity, that is, increasing the number of healthy years, is an important public health goal. A healthy diet and lifestyle cannot stop aging but can postpone the onset of many of the physiological changes and diseases that are common in older adults.

Molybdenum (Mo)

Molybdenum is a cofactor for enzymes involved in the metabolism of the amino acids methionine and cysteine and nitrogen-containing compounds such as DNA and RNA.

The Nutritional Needs of Infancy

Newborns grow more rapidly and require more energy and protein per kilogram of body weight than at any other time in life. Fat and water needs are also proportionately higher than those of adults. A diet that meets energy, protein, and fat needs may not necessarily meet the needs for iron, fluoride, and vitamins D and K. Growth, which is assessed using growth charts, is the best indicator of adequate nutrition in an infant. Growth charts can be used to compare an infant's growth with the growth of healthy infants of the same age.

Vitamin B6

Pyridoxal phosphate, the coenzyme form of this vitamin, is needed for the activity of more than 100 enzymes involved in the metabolism of carbohydrate, fat, and protein. a coenzyme for transamination, deamination, and decarboxylation reactions and is therefore particularly important for amino acid metabolism. deficiency causes neurological symptoms, anemia due to impaired hemoglobin synthesis, poor immune function, and elevated levels of homocysteine, which can increase the risk of cardiovascular disease. High intakes from supplements can cause nervous system abnormalities.

Calcium (Ca)

Sources of calcium in the American diet include dairy products, fish consumed with bones, and leafy green vegetables. Fortified foods and supplements also contribute to calcium intake. Sufficient calcium absorption depends on adequate levels of vitamin D. The absorption of calcium is reduced by the presence of tannins, fiber, phytates, and oxalates. Calcium absorption varies with life stage and is highest during infancy and pregnancy, when needs are greatest. Most of the calcium in the body is in bone. Calcium not found in bone is essential for cell communication, nerve transmission, muscle contraction, blood clotting, and blood pressure regulation. Blood levels of calcium are regulated by parathyroid hormone (PTH) and calcitonin. PTH stimulates the release of calcium from bone, decreases calcium excretion by the kidney, and activates vitamin D to increase the amount of calcium absorbed from the gastrointestinal tract and released from bone. Calcitonin blocks calcium release from bone. Calcium deficiency can reduce bone mass and increase the risk of osteoporosis. The RDA for calcium ranges from 1000 to 1200 mg/day for adults and is 1300 mg/day in adolescents and pregnant and lactating women. Too much calcium can contribute to the formation of kidney stones, raise blood calcium levels, and interfere with the absorption of other minerals.

Physical Activity Recommendations

The current physical activity recommendations suggest a minimum of 150 minutes per week of moderate-intensity aerobic activity. Greater benefits are obtained from exercising longer or at higher intensity. In addition to aerobic exercise, an exercise program should include muscle-strengthening exercise and exercises to promote flexibility, balance, and agility. Time spent in strength and flexibility training does not count toward the goal of 150 minutes of aerobic exercise per week. Exercise recommendations for children suggest a minimum of 60 minutes of activity per day, some of which is muscle strengthening and bone strengthening. Activities should be age appropriate. An exercise program should include activities that are enjoyable, convenient, and safe. Various combinations of exercise frequency, intensity, and duration can meet exercise goals. Rest is important to allow the body to recover and rebuild. In serious athletes, inadequate rest can lead to overtraining syndrome.

Choline and Other Vitamin-Like Compounds

There are a number of substances, such as carnitine, lipoic acid, and inositol, that perform vitamin-like functions in the body, but are not classified as vitamins because adequate amounts can be synthesized. Choline is considered an essential nutrient but is not currently classified as a vitamin. Choline can be synthesized in the human body, but the amounts are generally not enough to meet needs. The best dietary sources of choline are egg yolks and meats.

Other Trace Elements

There is evidence that boron, arsenic, nickel, silicon, and vanadium may be essential in humans as well as animals. These elements may be necessary in small amounts, but can be toxic if consumed in excess.

Trace Minerals in Our Diet

Trace minerals are required by the body in an amount of 100 mg or less per day or present in the body in an amount of 0.01% or less of body weight. They include iron, zinc, copper, manganese, selenium, iodine, chromium, fluoride, and molybdenum.

Riboflavin

coenzymes are needed for the generation of ATP from carbohydrate, fat, and protein. deficiency is rarely seen alone because food sources of this are also sources of other B vitamins and because this is needed for the utilization of several other vitamins. No toxicity has been identified.

Water: The Internal Sea

essential nutrient that provides many functions in the body. The polar structure of water allows it to act as a solvent for the molecules and chemical reactions involved in metabolism. Water helps to transport other nutrients and waste products within the body and to excrete wastes from the body. It also helps to protect the body, regulate body temperature, and lubricate areas such as the eyes and the joints. The adult human body is about 60% water by weight. Body water is distributed between intracellular and extracellular compartments. The amount in each compartment depends largely on the concentration of solutes. Since water will diffuse by osmosis from a compartment with a lower concentration of solutes to one with a higher concentration, changes in the concentration of electrolytes and other solutes in each compartment cause changes in the distribution of water.

Sulfur (S)

is in the diet as preformed organic molecules such as the amino acids methionine and cysteine, which are needed to synthesize proteins and glutathione, and the vitamins thiamin and biotin, needed for energy metabolism. is also part of a buffer system that regulates acid-base balance. A dietary deficiency is unknown in the absence of protein malnutrition.

Folate (Folic Acid)

necessary for the synthesis of DNA, so it is especially important for rapidly dividing cells. deficiency results in macrocytic anemia and can cause an increase in homocysteine levels. Low levels of this before and during early pregnancy are associated with an increased incidence of neural tube defects in the offspring. A high intake of this can mask the anemia caused by vitamin B12 deficiency. Low intakes of this have been associated with an increased risk of cardiovascular disease and certain types of cancer. It is recommended that women of childbearing age consume 400 μg of this from fortified foods and supplements in addition to the amount found in a varied diet.

Thiamin

required for the formation of acetyl-CoA from pyruvate and for a reaction in the citric acid cycle and is therefore particularly important for the production of ATP from glucose. It is also needed for the synthesis of the neurotransmitter acetylcholine. deficiency causes nervous system abnormalities (dry beriberi) or cardiovascular problems (wet beriberi). Deficiencies are common in people with alcoholism. No toxicity has been identified.

Keeping Older Adults Healthy

A healthy diet and regular exercise can prevent malnutrition, delay the onset of chronic conditions, and increase independence in older adults. MyPlate can be used to determine the amounts of food from each food group needed by adults of all ages. Meals for older adults must be nutrient dense, provide plenty of fluid and fiber, and consider individual medical, psychological, social, and economic circumstances. Supplements of calcium, vitamin D, and vitamin B12 may be beneficial. In some cases, assistance with shopping and meal preparation may be needed. Underweight and obesity increase health risks in older adults. Weight management should focus on diet and exercise to maintain lean body mass. A physical activity program for older adults should include activities that improve endurance, strength, flexibility, and balance. Activities should be tailored to the individual's needs and likes. Exercise classes are advantageous for older adults because they provide both social interaction and professional support and instruction. A well-planned exercise program can reduce the risk of chronic disease, improve mobility, increase independence, and reduce the risk of falls and injuries. The DETERMINE checklist helps identify older adults who are at risk for malnutrition. The federal Older Americans Act includes programs that provide older adults with low-cost or free meals in their homes or in a social setting. Participation in these programs has been found to improve nutrient intake or nutritional status.

What Causes Aging?

As organisms become older, the number of cells they contain decreases and the function of the remaining cells declines. This reduces reserve capacity, lowering the organism's ability to maintain homeostasis and increasing the risk of disease. The loss of cells and cell function that causes aging is believed to be due both to genetic factors that limit cell life and the accumulation of cellular damage over time. How long we live and how long we remain healthy is determined by a combination of genetic, environmental, and lifestyle factors.

Minerals. Osteoporosis. and Bone Health

Bone consists of a protein matrix hardened by mineral deposits. It is a living tissue that is constantly being broken down and re-formed in a process known as bone remodeling. Early in life, bone formation occurs more rapidly than bone breakdown to allow bone growth and an increase in bone mass. Loss of bone due to age and other factors increases the risk of developing osteoporosis, a condition in which loss of bone mass increases the risk of bone fractures. The risk of osteoporosis is related to the level of peak bone mass and the rate of bone loss. These are affected by age, gender, body size, hormone levels, genetics, smoking, alcohol use, exercise, and diet. Peak bone mass occurs in young adulthood. With age, bone breakdown begins to outpace formation, causing a decrease in bone mass. this is accelerated in women for about 5 to 10 years surrounding menopause. An active lifestyle along with adequate calcium and vitamin D intake throughout life helps maintain bone mass and prevent osteoporosis. Once it has developed, osteoporosis is treated with supplemental calcium and vitamin D and medications that inhibit bone breakdown and increase calcium absorption.

Feeding the Newborn

Breast milk is the ideal food for new babies. It is designed specifically for the human newborn. is always available, requires no special equipment, mixing, or sterilization, and provides immune protection. Infant formulas are patterned after human milk and provide adequate nutrition to the baby. Infant formulas are the best option when the mother is ill or is taking prescription or illicit drugs, or when the infant has special nutritional needs. The major disadvantages of formula feeding are the potential for bacterial contamination, overfeeding, and the possibility of errors in mixing formula.

Chromium (Cr)

Chromium is found in liver, brewer's yeast, nuts, and whole grains. Chromium is needed for normal insulin action and glucose utilization. Overt chromium deficiency is not a problem in the U.S. population. Recommended chromium intake is 35 μg/day for men and 25 μg/day for women. Chromium supplements are marketed to control blood sugar and increase lean body mass. Controlled trials have reported no dietary chromium toxicity in humans.

Food and Drink to Maximize Performance

Competitive endurance athletes may benefit from a dietary regimen called glycogen supercompensation (carbohydrate loading), which maximizes glycogen stores before an event. Meals eaten before competition should help ensure adequate hydration, provide moderate amounts of protein, be high enough in carbohydrate to maximize glycogen stores, be low in fat and fiber to speed gastric emptying, and satisfy the psychological needs of the athlete. During exercise lasting less than 45 minutes, no food is needed. For activity lasting 45 minutes or longer, carbohydrate is needed to maintain glucose supplies and thus delay fatigue. For exercise lasting more than an hour, a sodium-containing snack or beverage will reduce the risk of hyponatremia, improve glucose and water absorption, and stimulate thirst. Postcompetition meals and snacks should replace lost fluids and electrolytes, provide carbohydrate to restore muscle and liver glycogen, and provide protein both to stimulate muscle protein synthesis and to provide the amino acids needed for protein synthesis and repair.

Adolescents

During adolescence, body composition changes and the nutritional requirements of boys and girls diverge. Males gain more lean body tissue, while females have a proportionally greater increase in body fat. During adolescence, accelerated growth and sexual maturation have an impact on nutrient requirements. Total energy and protein requirements are higher than at any other time of life. Vitamin requirements increase to meet the needs of rapid growth. Vitamin D, calcium, iron, and zinc are likely to be low in the adolescent diet. Intake of vitamin D and calcium is often low because teens drink soda instead of milk. Iron deficiency anemia is common, especially in girls as they begin losing iron through menstruation. Adolescent nutrient needs can be met by following the recommendations of MyPlate. Since meals are frequently missed, healthy snacks should be included in the diet.

The Nutritional Needs of Pregnancy

During pregnancy, the requirements for energy, protein, water, and some vitamins and minerals rise above levels for nonpregnant women. The need for B vitamins is increased to support increased energy and protein metabolism. The RDA for calcium is not increased because the greater need during pregnancy is met by an increase in absorption. Vitamin D deficiency is a concern, particularly for darker-skinned women. Adequate folic acid early in pregnancy reduces the risk of neural tube defects. Iron is needed for red blood cell synthesis, so requirements are high and deficiency is common during pregnancy. Even with a nutrient-dense diet that follows MyPlate recommendations, supplements of folic acid and iron are recommended during pregnancy.

Exercise and Energy Metabolism

During the first 10 to 15 seconds of exercise, ATP and creatine phosphate stored in the muscle provide energy to fuel activity. During the next two to three minutes, the amount of oxygen at the muscle remains limited, so ATP is generated by the anaerobic metabolism of glucose. After a few minutes, the delivery of oxygen at the muscle increases, and ATP can be generated by aerobic metabolism. Aerobic metabolism is more efficient than anaerobic metabolism and can utilize glucose, fatty acids, and amino acids as energy sources. The use of protein as an energy source increases when exercise continues for many hours. For short-term, high-intensity activity, ATP is generated primarily from the anaerobic metabolism of glucose from muscle glycogen stores. Exercise that relies on anaerobic metabolism depletes glycogen rapidly, resulting in fatigue. For lower-intensity exercise of longer duration, aerobic metabolism predominates, and both glucose and fatty acids are important fuel sources. Fitness training causes changes in the cardiovascular system and muscles that improve oxygen delivery and utilization and increase glycogen stores, allowing aerobic exercise to be sustained for longer periods at higher intensity.

Nutritional Needs and Concerns of Older Adults

Energy needs are lower in older than in younger adults due to decreases in physical activity, basal metabolic rate, and the thermic effect of food, but the needs for most nutrients remain the same or increase. Protein needs are increased by the changes that typically occur with age, so a diet that has plentiful amounts of lean sources of protein is recommended. Intakes of fiber and water are often lower than recommended, increasing the risk of dehydration and constipation. Low intakes, reduced absorption, and changes in the metabolism of certain micronutrients including vitamin B12, vitamin D, and calcium put older adults at risk of deficiency. Iron requirements decrease in women after menopause, but many older adults are at risk of iron deficiency due to blood loss from disease or medications.

Selenium (Se)

Excellent dietary sources of selenium include seafood, eggs, and organ meats. The selenium content of plant foods depends on the selenium content of the soil where they are grown, and the selenium content of animal products is affected by the amount of selenium in their feed. Selenium protects against oxidative damage as an essential part of the enzyme glutathione peroxidase. Glutathione peroxidase destroys peroxides before they can form free radicals. Adequate dietary selenium reduces the need for vitamin E. Severe selenium deficiency is rare except in regions with very low soil selenium content and limited diets. In China, selenium deficiency contributes to the development of a heart condition known as Keshan disease. Low selenium intake has been linked to increased cancer risk. The RDA for selenium for adults is 55 μg/day. Very high selenium intake (5 mg/day) causes fingernail changes and hair loss. Selenium supplements are marketed with claims that they will protect against environmental pollutants, prevent cancer and heart disease, slow the aging process, and improve immune function. Supplements that increase intake above the RDA do not provide additional benefits and could have adverse effects.

Manganese (Mn)

Good dietary sources of manganese include whole grains and nuts. The AI is 2.3 mg/day for men and 1.8 mg/day for women. Manganese is necessary for the activity of some enzymes, including a form of the antioxidant enzyme superoxide dismutase. Manganese is involved in amino acid, carbohydrate, and lipid metabolism.

Copper (Cu)

Good sources of copper in the diet include organ meats, seafood, nuts, and seeds. The absorption of copper is affected by the presence of other minerals in the diet. The zinc content of the diet can have a major impact on copper absorption. Copper functions in a number of important proteins that affect iron and lipid metabolism, synthesis of connective tissue, and antioxidant protection. Copper is transported in the blood bound to proteins such as ceruloplasmin. A copper deficiency can cause anemia and connective tissue abnormalities. Copper toxicity from dietary sources is extremely rare. The RDA for copper for adults is 900 μg/day.

Zinc (Zn)

Good sources of zinc include re,d meats, eggs, dairy products, and whole grains. Zinc from animal sources is better absorbed than that from plant foods. Phytates inhibit zinc absorption from many plant sources. Zinc absorption is regulated by zinc transport proteins that determine how much zinc is moved into and out of the mucosal cell and by metallothionein, a protein that binds zinc in the mucosal cell. When zinc intake is high, more metallothionein is synthesized and zinc absorption is limited. Zinc is needed for the activity of many enzymes, including a form of the antioxidant enzyme superoxide dismutase and enzymes that function in the synthesis of proteins, DNA, and RNA. in carbohydrate metabolism and in acid-base balance. Many of the functions of zinc are related to its role in gene expression. Zinc is needed for tissue growth and repair, development of sex organs and bone, and proper immune function. Zinc deficiency results in poor growth, delayed sexual maturation, skin changes, hair loss, skeletal abnormalities, and depressed immunity. The RDA for zinc is 11 mg/day for adult men and 8 mg/day for adult women. Since copper binds more tightly to metallothionein than zinc, an excess of zinc, which stimulates metallothionein synthesis, can trap copper in the mucosal cells, causing a copper deficiency. When administered within 24 hours of the onset of common cold symptoms, supplemental zinc in lozenge form can reduce the duration of cold symptoms.

Nourishing Infants Toddlers and Children

Growth that follows standard patterns is the best indicator of adequate nutrition. BMI-for-age growth charts can be used to evaluate whether a child is normal weight, underweight, overweight, or obese. Energy and protein needs per kilogram of body weight decrease as children grow, but total needs increase because of the increase in total body weight and activity level. Children need a greater percentage of dietary fat and the same percentage of carbohydrates as adults. Dietary carbohydrates should come primarily from whole grains, vegetables, fruits, and milk. Baked goods, candy, and soda should be limited. Under most situations, water needs in children can be met by consuming enough fluid to alleviate thirst. Activity and a hot environment increase water needs. As with adults, the typical sodium intake in children and teens currently exceeds the recommended amounts. Calcium, vitamin D, and iron intakes are often low in children's diets. Adequate calcium and vitamin D are important for preventing osteoporosis later in life, but intakes are declining due to reductions in the consumption of milk. Low iron intake and excessive milk consumption contribute to iron deficiency. Introducing solid foods between 4 and 6 months of age adds iron and other nutrients to the diet. Newly introduced foods should be appropriate to the child's stage of development and offered one at a time to monitor for food allergies. In order for children to meet nutrient needs and develop nutritious habits, a variety of healthy foods should be offered at meals and snacks throughout the day. The National School Lunch Program provides low-cost school lunches designed to meet nutrient needs and promote healthy diets. Some children can benefit from vitamin/mineral supplements, but children who consume a well-selected, varied diet can meet all their vitamin and mineral requirements with food.

Nutrition Physical Activity and Health

How fit an individual is depends on his or her cardiorespiratory endurance, muscle strength, muscle endurance, flexibility, balance, and body composition. Regular aerobic exercise increases aerobic capacity and resistance exercise increases muscle strength. Regular physical activity can reduce the risk of chronic diseases such as obesity, heart disease, diabetes, osteoporosis, and certain types of cancer. Physical activity helps manage body weight by increasing energy expenditure and by increasing the proportion of body weight that is lean tissue. Exercise also improves brain function, reduces depression and anxiety, improves sleep patterns, and promotes well-being.

Nutrition and Health Concerns in Infants and Children

In sensitive individuals food allergies are triggered by the absorption of food allergens, most of which are proteins. Food allergies involve antibody production by the immune system. They may develop during infancy because the infant's immature gastrointestinal tract is more likely to absorb incompletely digested proteins. Specific foods that cause allergies can be identified by an elimination diet and food challenge. Unlike food allergies, food intolerances do not involve antibody production. Dietary patterns high in sugars combined with poor dental hygiene put children at risk of dental caries. Sugar intake has been accused of worsening attention deficit/hyperactivity disorder symptoms, but there is little evidence that that is the case. Lack of sleep, overstimulation, the desire for more attention, lack of physical activity, and caffeine consumption may contribute to hyperactivity. Children's health is harmed by lead. Lead disrupts the activity of neurotransmitters and thus interferes with the functioning of the nervous system. Due to reductions in the use of lead, the number of children with high blood lead levels has declined, but low-income children are still at risk. An unhealthy food environment is contributing to the growing problem of obesity among children. Watching television contributes to childhood obesity by promoting snacking on high-calorie foods and by reducing the amount of exercise children get. Fast food meals contribute to obesity because they are high in calories, in addition they are typically low in fruits, vegetables, and dairy. Solutions to the problem of childhood obesity involve action from government, the food industry, health-care providers, communities, schools, and parents and families. Individuals who are overweight need to change behaviors to decrease food intake and increase activity.

Meeting Iron Needs

Iron deficiency is the most common nutritional deficiency worldwide. When iron is deficient, adequate hemoglobin cannot be made, resulting in iron deficiency anemia, which is characterized by small, pale red blood cells. The RDA for iron for women ages 19 to 50 is 18 mg/day, more than double the RDA of 8 mg/day for adult men and postmenopausal women. Iron can be toxic. Ingestion of a single large dose can be fatal. The accumulation of iron in the body over time causes heart and liver damage and contributes to diabetes and cancer. The most common cause of chronic iron overload is hemochromatosis, a genetic disorder in which too much iron is absorbed. Both the amount and bioavailability of dietary iron must be considered when planning a diet to meet iron needs. Supplements are often recommended to groups at risk of deficiency, such as small children, women of childbearing age, and pregnant women.

Iron (Fe) Sources and Functions

Iron is found in both plant and animal foods. Heme iron is an easily absorbable form that is found in animal products. Nonheme iron, which is less well absorbed, comes from both animal and plant sources. The amount of iron that is absorbed from the diet depends on the type of iron and the presence of other dietary components. Heme iron is better absorbed than nonheme iron. The absorption of nonheme iron can be increased by consuming it with meat, vitamin C, or other acids. its absorption is decreased by consuming it with foods containing fiber, phytates, oxalates, or tannins. Iron homeostasis is regulated at the intestine. If iron stores are low, more iron is transferred from the mucosal cells to the blood and bound to transferrin for transport to body cells. When body stores are high, less iron is transported from the mucosa into the blood and more is bound to ferritin and lost when mucosal cells die. Iron functions as part of hemoglobin, which transports oxygen in the blood, and myoglobin, which enhances the amount of oxygen available during muscle contraction. Iron is also a component of proteins involved in ATP production and is needed for activity of the antioxidant enzyme catalase.

Magnesium (Mg)

Magnesium is found in leafy greens such as spinach and kale because it is a component of chlorophyll. Nuts, seeds, bananas, and the germ and bran of whole grains are also good sources. About half of the magnesium in the diet is absorbed, and the percentage decreases as intake increases. The active form of vitamin D can enhance magnesium absorption and the presence of phytates decreases absorption. Magnesium is important for bone health, and it is needed as a cofactor for numerous reactions throughout the body. In reactions involved in energy metabolism it acts as an enzyme activator and stabilizer of ATP. It is also needed to maintain membrane potentials, thus it is essential for nerve and muscle conductivity. Homeostasis is regulated by the kidney. Magnesium deficiency is rare in the general population, but intakes generally do not meet recommendations. Deficiency does occur in those with alcoholism, malnutrition, kidney disease, and gastrointestinal disease. Symptoms include nausea, muscle weakness and cramping, irritability, mental derangement, and changes in blood pressure and heartbeat. The RDA for magnesium is 400 mg/day for young men and 310 mg/day for young women. No adverse effects have been observed from ingestion of magnesium from food, but toxicity may occur from magnesium-containing drugs and supplements.

Ergogenic Aids: Do Supplements Enhance Athletic Performance?

Many types of ergogenic aids are marketed to improve athletic performance. An individual risk-benefit analysis should be used to determine whether a supplement is appropriate for you. Vitamin and mineral supplements are usually not necessary for athletes who are consuming a diet that meets their energy needs. Protein supplements are popular for athletes trying to build muscle. Adequate protein is necessary to support muscle growth and repair, but dietary protein can meet this need as effectively as the protein provided by supplements. Anabolic steroids combined with resistance-training exercise increase muscle size and strength, but these supplements are illegal and have dangerous side effects. Creatine and β-alanine supplements have been shown to improve performance in short-duration, high-intensity exercise. Caffeine use can improve performance in endurance activities. EPO increases endurance by boosting the number of red blood cells, but it is a banned substance that can contribute to excessive blood clotting, heart attacks, and strokes. A healthy diet is needed to optimize athletic performance. Beverages and foods that supply fluids and energy can further enhance performance, and there are a few supplements that benefit specific activities.

Lactation

Milk production and letdown are triggered by the hormones prolactin and oxytocin, respectively. They are secreted in response to the suckling of the infant. Lactation requires energy and nutrients from the mother to produce adequate milk. The energy for milk production comes from the diet and maternal fat stores. During lactation, the need for water and many vitamins and minerals is even greater than during pregnancy.

What Are Minerals?

Minerals are elements needed by the body to regulate chemical reactions and provide structure. They are divided into major minerals and trace minerals, based on the amount required in the diet and present in the body. They are found in both plant and animal foods. Minerals are added to some foods through fortification and get into others as a result of contamination. Dietary supplements are also a source of minerals. Deficiencies of certain minerals are world health problems. Mineral bioavailability is affected by body needs as well as interactions with other minerals, vitamins, and dietary components, such as fiber, phytates, oxylates, and tannins. Minerals contribute to the body's structure and help regulate body processes, often as cofactors.

Fluoride (F)

Most of the fluoride in the diet in the United States comes from fluoridated drinking water and toothpaste. Fluoride is necessary for the maintenance of bones and teeth. Adequate dietary fluoride helps prevent dental caries in children and adults. Low fluoride intake increases the risk of dental caries. Excess fluoride causes dental fluorosis in children. The recommended fluoride intake from all sources is set at 0.05 mg per kilogram per day for everyone 6 months of age and older because it protects against dental caries with no adverse effects.

Factors That Increase the Risks of Pregnancy

Nutritional status is important before, during, and after pregnancy. Poor nutrition before pregnancy can decrease fertility or lead to a poor pregnancy outcome. Malnutrition during pregnancy can affect fetal growth and development and the risk that the child will develop chronic disease later in life. Poor maternal health status, age younger than 20 or older than 35, a short interval between pregnancies, a history of poor reproductive outcomes, and poverty all increase the risk of complications for the mother and baby. Because the embryo and fetus are developing and growing rapidly, they are susceptible to damage from physical, chemical, or other environmental teratogens. Mercury in food, food-borne pathogens, cigarette smoking, alcohol use, and certain prescription and illegal drugs can interfere with growth and development of the embryo and fetus.

Phosphorus (P)

Phosphorus is more widely distributed in the diet than calcium. It is found in dairy products such as milk, yogurt, and cheese. meat, cereals, bran, eggs, nuts, and fish are also good sources. Food additives used in baked goods, cheese, processed meats, and soft drinks also contribute to dietary phosphorus. About 60 to 70% of the phosphorus in a typical diet is absorbed. Vitamin D aids phosphorus absorption via an active mechanism, but most absorption occurs by a mechanism that does not depend on vitamin D. Most of the phosphorus in the body is found in bones and teeth. In addition to its structural role in these tissues, phosphorus is an essential component of phospholipids, ATP, and DNA and RNA. Phosphorus is also part of a buffer system that helps prevent changes in pH. Phosphorus deficiency is rare in healthy people because phosphorus is so widely distributed in foods. Deficiency can lead to bone loss, weakness, and loss of appetite. The RDA for adults is 700 mg of phosphorus per day. Symptoms related to high phosphorus intake are rare in healthy adults, but excessive intakes can lead to bone resorption. The levels of phosphorus intake typical in the United States are not believed to affect bone health as long as calcium intake is adequate.

The Physiology of Pregnancy

Pregnancy begins with the fertilization of an egg by a sperm. About two weeks after fertilization, implantation is complete. The embryo grows, and the cells differentiate to form the organs and structures of the body. Growth and maturation continue in the fetal period, which begins at 9 weeks, and continues until birth, about 38 weeks after fertilization. During pregnancy, the placenta develops, maternal blood volume increases, the uterus and supporting muscles expand, body fat is deposited, the heart, lungs, and kidneys work harder, the breasts enlarge, and total body weight increases. Changes in the mother and growth of the fetus contribute to weight gain. Recommended weight gain during pregnancy is 25 to 35 lb (11 to 16 kg) for normal-weight women. Too little or too much weight gain can place both mother and baby at risk. Weight loss should never be attempted during pregnancy. Normal-weight, underweight, overweight, and obese mothers should all gain weight at a steady rate during pregnancy, but the total amount of weight gain recommended depends on prepregnancy weight. During healthy pregnancies, a carefully planned program of moderate-intensity exercise can be safe and beneficial. Changes in blood volume and hormone levels and the enlargement of the uterus can result in edema, morning sickness, heartburn, constipation, and hemorrhoids during pregnancy. The hypertensive disorders of pregnancy include chronic hypertension, gestational hypertension, and preeclampsia, which can lead to life-threatening eclampsia. Gestational diabetes can result in a large-for-gestational-age baby.

Healthy Electrolyte Intakes

Recommendations for health suggest that we increase our intake of potassium and consume less sodium. The recommended salt intake is 3.8 g/day for adults ages 19 to 50. Because salt is 40% sodium and 60% chloride by weight, this represents an AI of 1500 mg of sodium and 2300 mg of chloride. The UL for sodium, which is based on the increase in blood pressure seen with higher sodium intakes, is only 2300 mg/day. The AI for potassium is 4700 mg/day. Typical potassium intake is less than 3000 mg/day, so underconsumption is a concern. No UL has been set for potassium. Public health recommendations including the Dietary Guidelines suggest that Americans consume a dietary pattern that is high in fruits, vegetables, whole grains, legumes, nuts, and seeds and provides low-fat dairy products and lean meat, fish, and poultry. This dietary pattern, which can be achieved by following the recommendations of the DASH Eating Plan or MyPlate, contains less sodium and more potassium than the typical American diet.

Special Concerns of Teenagers

Teens often turn to vegetarian diets, sometimes for environmental reasons and sometimes for weight control. Poorly planned vegetarian diets can put teens at risk of iron, zinc, calcium, vitamin D, or vitamin B12 deficiency. Poor food choices can result in vegetarian diets that are high in saturated fat and low in fiber. Psychosocial changes occurring during the adolescent years make physical appearance of great concern. Eating disorders are more common in adolescence than at any other time. Adolescent athletes are susceptible to nutrition misinformation, and they may experiment with dangerous practices such as using anabolic steroids to increase muscle mass or fad diets and fluid restriction to lose weight. During the teen years, pregnancy, the use of oral contraceptives, and tobacco may affect nutritional status. Alcohol consumption and overconsumption often start in the teen years and can have negative nutritional and social consequences.

Electrolytes: Salts of the Internal Sea

The U.S. diet is abundant in sodium and chloride from processed foods and table salt but generally low in potassium, which is high in unprocessed foods such as fresh fruits and vegetables. The minerals sodium, chloride, and potassium are electrolytes important in the maintenance of fluid balance and the formation of membrane potentials essential for nerve transmission and muscle contraction. Electrolyte and fluid homeostasis is regulated primarily by the kidneys. A decrease in blood pressure or blood volume signals the release of the enzyme renin, which helps form angiotensin II. Angiotensin II causes blood vessels to constrict and the hormone aldosterone to be released. Aldosterone causes the kidneys to reabsorb sodium and hence water, thereby preventing any further loss in blood volume. Failure of these regulatory mechanisms may be a cause of hypertension. Low levels of sodium, chloride, and potassium can occur when water and electrolyte losses are increased due to excessive sweating, chronic diarrhea or vomiting, or kidney disorders. High blood sodium most commonly results from dehydration.

Niacin

The amino acid tryptophan can be converted into this, so tryptophan from dietary protein can meet some of the this vitamin's requirement. coenzymes are important in the breakdown of carbohydrate, fat, and protein to provide energy and in the synthesis of fatty acids and sterols. deficiency results in pellagra, which is characterized by dermatitis, diarrhea, dementia, and finally, if untreated, death. Supplements of the nicotinic acid form of this can lower elevated blood cholesterol but frequently cause toxicity symptoms such as flushing, tingling sensations, nausea, and a red skin rash.

Energy and Nutrient Needs for Physical Activity

The amount of energy needed for activity depends on the intensity, duration, and frequency of the activity, as well as the characteristics of the exerciser. The EER is increased by increases in activity level. The desire for weight loss to improve performance can lead to unhealthy weight-loss practices and eating disorders. Athletes who restrict food intake may develop RED-S. The female athlete triad, which is a component of RED-S, is a combination of low energy availability, menstrual dysfuntion, and low bone density. A combination of adequate protein, resistance exercise, and increased energy intake can help promote an increase in body weight and muscle mass. Carbohydrate is an important fuel for the brain and muscles during exercise. The amount needed to maintain blood glucose and glycogen stores depends on the activity patterns and ranges from 3 to 12 g/kg/day. Dietary fat recommendations are the same as for the general population. The protein needs of athletes are higher to support changes in metabolism and to maintain and repair muscle and other lean tissues. Sufficient vitamins and minerals are needed to generate ATP from macronutrients, maintain and repair tissues, and transport oxygen and wastes to and from the cells. Most athletes who consume a varied diet that meets their energy needs also meet their vitamin and mineral needs. Those who restrict their food intake may be at risk for deficiencies. Increased iron needs and greater iron losses due to fitness training put athletes, particularly female athletes, at risk of iron deficiency. Athletes are also at risk of deficiencies of antioxidant nutrients, calcium, and vitamin D.

Vitamin C

The best food sources are citrus fruits. necessary for the synthesis and maintenance of collagen and for the synthesis of hormones and neurotransmitters. is also a water-soluble antioxidant. Antioxidants protect the body from reactive oxygen molecules such as free radicals. These molecules are generated from normal body reactions and come from the environment. They cause damage by stealing electrons from DNA, proteins, carbohydrates, and unsaturated fatty acids. deficiency, called scurvy, is characterized by poor wound healing, bleeding, and other symptoms related to the improper formation and maintenance of collagen. supplements are common and are frequently used to reduce the symptoms of the common cold.

Iodine (I)

The best sources of iodine in the diet are seafood, foods grown in or near the sea, and iodized salt. Iodine is an essential component of thyroid hormones, which promote protein synthesis and regulate basal metabolic rate, growth, and development. When iodine is deficient, continued release of thyroid-stimulating hormone causes the thyroid gland to enlarge, forming a goiter. Iodine deficiency during pregnancy causes a condition in the offspring known as cretinism, which is characterized by growth failure and developmental disability. Iodine deficiency during childhood and adolescence can impair cognitive function. Iodized salt has virtually eliminated iodine deficiency in North America. Although salt iodization is being used successfully worldwide to prevent iodine deficiency, iodine deficiency remains a world health problem. The RDA for iodine in adult men and women is 150 μg/day. Acute toxicity can occur with very large doses of iodine. Chronically high intakes of iodine can cause an enlargement of the thyroid gland that resembles goiter.

Starting Right for a Healthy Life

The current diet of American children is low in fruits, vegetables, whole grains, dairy, and seafood and high in processed foods that are high in solid fat, salt, and added sugars. The poor diet and low activity level of children in the United States contribute to obesity, diabetes, elevated blood pressure, and unhealthy blood lipid levels. Healthy eating habits learned in childhood set the stage for nutrition and health in the adult years.

Aging and the Risk of Malnutrition

The risk of malnutrition increases with age due to the physiological changes that accompany aging. There are changes in the sense of smell that affect the appeal of food, changes in vision that affect the ability to prepare food, changes in digestion and absorption that decrease the intake and absorption of nutrients, changes in metabolism that affect nutrient utilization, changes in weight and body composition that increase health risks and reduce independence, changes in hormonal patterns that affect body function, and changes in immune function that increase the risk of infectious and chronic disease. Both infectious and chronic diseases affect nutrient requirements and the ability to consume a nutritious diet. Aging increases the incidence of diseases that reduce mobility and cognitive function, limiting the ability to acquire, prepare, and consume food. The medications used to treat disease also affect nutrition, especially when the medications are taken over long periods of time and when multiple medications are taken simultaneously. Low income levels increase the risk of malnutrition among older adults by limiting the ability to purchase food. Loss of independence contributes to depression, which makes meals less appetizing and decreases the quantity and quality of foods consumed.

What Are Vitamins?

Vitamins are essential organic nutrients that do not provide energy and are required in small quantities in the diet. The bioavailability of a vitamin depends on how much can be absorbed and used by the body. The ability to store and excrete vitamins helps to regulate the amount present in the body. Water-soluble vitamins are generally excreted more easily than and not stored as well as fat-soluble vitamins. Vitamins are needed to promote and regulate body processes that are essential for growth, reproduction, and tissue maintenance. Each vitamin has one or more functions: Many are coenzymes, some are antioxidants. More than one vitamin is typically needed to ensure the health of a particular organ or system.

Water Balance

Water cannot be stored, so intake must balance losses to maintain homeostasis. We consume water both in liquids and in solid foods. Fluid intake is stimulated by the sensation of thirst, which occurs in response to a decrease in blood volume and an increase in the concentration of solutes. Water is lost from the body in urine and feces, through evaporation from the skin and lungs, and in sweat. The kidneys are the primary regulator of water output. If water intake is low, antidiuretic hormone will cause the kidneys to conserve water. If water intake is high, more water will be excreted in the urine. Dehydration can occur if water intake is too low or output is excessive. Mild dehydration can cause headache, fatigue, loss of appetite, dry eyes and mouth, and dark-colored urine. Severe dehydration can be fatal. Water intoxication is not as common as dehydration. It causes hyponatremia, which can result in abnormal fluid accumulation in body tissues. The recommended intake of water is 2.7 L/day for adult women and 3.7 L/day for adult men, needs vary depending on environmental conditions and activity level.

Fluid Needs for Physical Activity

Water is needed to ensure that the body can be cooled and that nutrients and oxygen can be delivered to body tissues. During exercise, water is lost in sweat and from evaporation through the lungs. If water intake is inadequate, dehydration can lead to a decline in exercise performance and increase the risk of heat-related illness. The risk of dehydration is increased when environmental temperature and humidity are elevated. Exercising in hot weather can lead to heat-related illnesses, including heat cramps, heat exhaustion, and heat stroke. Drinking plain water during extended exercise increases the risk of hyponatremia, a low concentration of sodium in the blood. Adequate fluid intake before exercise ensures that athletes begin exercise well hydrated. During exercise, athletes should drink enough fluid to limit weight loss to less than 2% of body weight. Plain water is an appropriate fluid to consume for exercise lasting less than 45 minutes. Beverages containing carbohydrate and sodium are recommended for exercise lasting 45 minutes or longer.

Pantothenic Acid

abundant in the food supply and deficiency is rare. part of CoA, which is required for the production of ATP from carbohydrate, fat, and protein and the synthesis of cholesterol and fatty acids. There is no RDA, but an AI has been established.

Vitamin B12

found almost exclusively in animal products. absorption of vitamin from food requires adequate levels of stomach acid, intrinsic factor, and pancreatic secretions. needed for the metabolism of folate and fatty acids and to maintain the insulating layer of myelin surrounding nerves. deficiency increases homocysteine levels and can result in anemia and permanent nerve damage. Pernicious anemia is an autoimmune disease that results in severe deficiency of this vitamin due to an absence of intrinsic factor. deficiency may also occur in vegans, who consume no animal products, and in older individuals with low stomach acid due to atrophic gastritis.

Biotin

needed for the synthesis of glucose and fatty acids and for the metabolism of certain amino acids. An RDA has not been established for this because some of our requirement for this vitamin is met by bacterial synthesis in the GI tract. However, an AI has been set. Toxicity has not been reported.