Nutrition Ch 8

upper level intake for vitamin A

3000 micrograms of preformed vitamin A(3000 RAE or 10,000 Internation Units) per day for adults.

vitamin D types

(Cholecalciferol, D3) Vitamin D is primarily considered a hormone. A cholesterol like substance in the skin is converted to prohormone vitamin D3 in the presence of ultraviolet B (UVB) rays from the sun. The prohormone is converted to its active hormone form.

why is vitamin K necessary?

Activation of blood-clotting factors Activation of proteins involved in bone metabolism

what is cancer?

A group of chronic disease characterized by cell that have mutated (have damaged genes). Cancerous (malignant) cells are "out of control" and can spread (metastasize). A mass of cancerous cells results in a malignant tumor. Carcinogens trigger cancer.

xerophthalmia

A lack of mucus production by the cells that line the cornea of the eye. The eye becomes dry. Dirt particles scratch the dry surface of the eye, and bacteria can infect the eye. If left untreated, vitamin A deficiency eventually leads to blindness.

how much vitamins in a slice of bread

A slice of bread weighs about 1 oz (28 g) Vitamins comprise only ~0.005% (1.48 mg) of the bread's weight

what is an antioxidant, and how do they work?

A substance that gives up electrons to stabilize free radicals Oxidation reactions can form radicals (or "free radicals"), substances with an unpaired electron. Oxidation = loss of electrons Reduction = gain of electrons Free Radical-is formed Most free radicals are highly reactive (unstable) Contain an unpaired electron A free radical can remove an electron from a more stable molecule, such as DNA, a protein, or a polyunsaturated fatty acid. How Do Antioxidants Work? Prevents or inhibits oxidation of a substance by combining with oxygen. The oxygen is tied up with the antioxidant and the desirable substance is protected. By giving up an electron to a free radical, an antioxidant protects other molecules. Action stabilizes the free radical Beta-carotene and vitamins E & C function as antioxidants.

what is a vitamin?

A vitamin is a complex organic compound that: Is not made by the body — or made in amounts that are enough to maintain good health; Occurs naturally in common foods; Causes a deficiency disorder when it is missing from the diet; Restores good health, if the deficiency disorder is treated early by supplying the missing substance.

fat soluble vitamins

A(retinol) D E(alpha-tocopherol, other tocopherols) K Characteristics of fat soluble vitamins: Associated with lipids in foods and the body Do not dissolve in water or urine Stored in the body and may be toxic if consumed to much

what causes cells to become cancerous?

Aging (most occur in > 65 yrs) Family history Tobacco use Radiation exposure Certain environmental exposures Alcohol consumption Excessive body fat and inactivity

functions of vitamin E

Alpha-tocopherol Functions: Major fat-soluble antioxidant found in cell. Protects polyunsaturated fatty acids (cell membrane!!). Improves vitamin A absorption. Maintains nervous system and immune system function.

B-6 amino acid metabolism

As a coenzyme, B-6 involved in amino acid conversion of homocysteine to cysteine.

ways to maximize vitamin content of foods

Avoid buying wilted, bruised, or shriveled produce. Store at near freezing temperatures, in high humidity and air-tight containers. Cook in small amounts of water. Avoid cutting foods that will be cooked into small pieces. Use quick cooking methods such as microwaving, steaming, and stir-frying. Freeze produce to preserve vitamins.

reducing the risk of cancer

Avoid tobacco smoke exposure Achieve and maintain a healthy weight Adopt a physically active lifestyle Eat a healthy diet that limits red and processed meat intakes Eat a healthy diet that emphasizes plant foods

absorption of vitamin B-12

B-12 in food is bound to proteins HCL and pepsin required to release B-12 from proteins B-12 must bind to intrinsic factor for absorption.

betacarotene vitamin A

Beta-carotene (provitamin A) ; is known as a precursor of vitamin A. Plants contain pigments called carotenoids . These pigments can be turned into vitamin A in the body as needed. Beta-carotene is the orange-yellow pigment in carrots and is the most potent form of the provitamin A. Beta- carotene is converted within the intestinal cell, to retinol or retinal. Vitamin A is then re-esterified with fatty acids and transported through the lymph into the blood for uptake by the liver. There are two other provitamin A carotenoids: lutein and zeaxanthin. The macula of the eye contains the carotenoids lutein and zeaxanthin.

vitamin A and carotenoids as medicine?

CVD and Cancer Diets rich in fruits and vegetables associated with lower CVD risk Dietary supplements containing beta-carotene and other carotenoids fail to show benefit. Older studies suggested diets rich in carotenoids were associated with lower risk of cancers. Newer studies show dietary supplements containing beta-carotene failed to show benefit- may be harmful. Age-related Macular Degeneration (AMD) Diets that supply high amounts of certain carotenoids may lower risk of AMD.

vitamin A deficiency

Certain epithelial cells produce too much keratin Keratin - tough protein found in hair, nails, and outermost layers of skin Excess keratin: Skin becomes rough and bumpy Inner eyelid cells that normally secrete mucus to protect cornea become keratinized. Can result in xeropthalmia ("dry eye")

vitamin-like

Choline Dissolve in watery components of foods and the body Excreted in urine Most are not stored to a major extent Generally non toxic Choline is generally referred to as "vitamin like."

Riboflavin (Formally vitamin B-2) Functions

Coenzyme for metabolism of carbohydrate, lipids, and amino acids.

vitamin C functions

Collagen synthesis Vitamin C helps to form and maintain collagen. Collagen is a protein that gives strength to connective tissues Antioxidant activity-Vitamin C may donate electrons to radicals. Vitamin C may also donate electrons to Vitamin E, another antioxidant. Vitamin C taken in mega doses may encourage radical production( proxidant effect). High doses of Vitamin C tends to decrease the amount of Vitamin C absorbed. Excess Vitamin C is excreted through the kidneys. Other Roles: Immune system functioning Synthesis of bile, and certain neurotransmitters and hormones Facilates the absorption of nonheme iron

niacin adequacy and deficiency

Dietary Adequacy RDA = 14-16 mg/day Niacin is present in a bound form in corn and it is biologically unavailable for the body to use. The people in the South, during the early twentieth century developed pellagra due to eating corn and salt pork. Corn is rich in leucine and low in tryptophan. Tryptophan is a precursor to niacin. The body can make niacin from the tryptophan. Approximately 60 mg of tryptophan = 1 mg of niacin. Generally, a rule of thumb: if the protein in the diet is adequate, niacin will be adequate. Deficiency Pellagra—the "4 D's" of pellagra-Dermatitis, Diarrhea, Dementia, Death Early symptoms-poor appetite, weight loss and weakness

vitamin K adequacy, deficiency, and toxicity

Dietary Adequacy IA: 120 mcg/d for men; 90 mcg/d for women Vitamin K Deficiency May occur in newborns or people with impaired liver function or absorption, on long term antibiotic therapy. The intestinal tracts of newborns lacks sufficient amounts of bacteria to produce vitamin K to allow for blood clotting. Vitamin K is routinely given by injection shortly after birth to insure blood clotting. Adults may experience vitamin K deficiency due to long-standing fat malabsorption Vitamin K Toxicity None known Reduced effectiveness of oral medication used to reduce blood clotting such as coumadin.

thiamin adequacy, deficiency

Dietary Adequacy RDA = 1.2 mg/day (men) 1.1 mg/day (women) Deficiencies Beriberi: People are weak, have poor muscular coordination, and may develop cardiovascular problems and edema. Note severe pitting edema in woman's left leg. Beriberi is often seen in areas where polished white rice is a staple and has not been fortified. Wernicke-Korsakoff syndrome: Typically seen in alcoholics, because alcohol decreases absorption and increases excretion

riboflavin adequacy, deficiencies, and toxicity

Dietary Adequacy RDA = 1.3 mg/day (males) 1.1 mg/day (females) Deficiency May occur in people who do not drink milk or eat enriched grains Inflammation of the mouth and tongue dermatitis cracking of tisse around the corners of the mouth(cheilosis) eye disorders sensitivity to the sun confusion NO UPPER LIMITS OF TOXICITY HAVE BEEN SET.

B-6 adequacy and deficiency

Dietary Adequacy RDA = 1.3 to 1.7 mg/day Deficiency Rarely occurs, but signs and symptoms include: Dermatitis, anemia, convulsions, depression, irritation of nerves and confusion

vitamin C adequacy, deficiency, and toxicity

Dietary Adequacy RDA = 75 to 90 mg/day (smokers have higher RDAs) Toxicity Upper Limit is 2000 mg/day Kidneys excrete excess amounts of the vitamin & oxalate, a byproduct of vitamin C metabolism. Increases risk of oxalate kidney stones, particularly in susceptible persons Deficiency Scurvy Very rare in U.S., because about 10 mg/day prevents scurvy Signs & symptoms: poor wound healing, pinpoint hemorrhages, bleeding gums, bruises, & depression

vitamin D adequacy, deficiency, and upper limit intake

Dietary Adequacy RDA: 15 mcg/day for adults < 70 years of age Recommendation is likely to increase Vitamin D Deficiency Rickets Uncommon May develop in breastfed infants Osteomalacia — "adult rickets" Vitamin D Toxicity Upper Limit (UL): 100 mcg/day (4000 IU) The upper limit of vitamin D is set based on the risk of too much vitamin D causing deposits of calcium in the soft tissues including kidneys , heart and blood vessels. Calcium deposits can cause metabolic disturbances and cell death. High intakes of vitamin D can cause the symptoms of high blood calcium: weakness, loss of appetite, diarrhea, vomiting mental confusion and increased urine output.

vitamin B-12 adequacy, deficiency, and malabsorption

Dietary Adequacy RDA = 2.4 mcg/day Deficiency of Vitamin B-12 Nerve damage Megaloblastic RBCs Pernicious Anemia Genetic defect reduces production of intrinsic factor, resulting in poor B-12 absorption. Signs and symptoms of pernicious anemia: looks like a folate deficiency anemia(megaloblastic anemia),weakness, nerve damage, weakness, sore tongue, memory loss, confusion, difficulty walking and maintaining balance, and eventual death Food-Vitamin B-12(Cobalamin) Malabsorption can develop due to following: Declining gastric acid production (older adults) Alcoholism Gastric bypass surgeries Certain medications

vitamin A toxicity

Excess vitamin A (retinol) may lead to liver damage Increased birth defects, fetal malformations Increased risks of hip fracture Excess beta-carotene (carotenemia)

sources of vitamin D

Fatty fish such as sardines and salmon Fortified milk and yogurt Fortified ready -to-eat breakfast cereal Fortified milk Eggs, butter, liver, margarine (Contain a small amount of vitamin D; would need to eat large servings to fulfill requirement of vitamin D People who live south of the 37th parallel and are outdoors when sunlight is most intense are most likely synthesizing adequate prohormone D.

folate, folic acid

Folate-term used for several forms of vitamin B-6. Folic Acid is the synthetic form added to foods and supplements.

5 roles of vitamins

Have hormonal action (e.g., vitamin D) Participate in certain chemical reactions Regulate a variety of body processes Cell division and development Growth and maintenance of tissues

choline for humans

Humans also require choline, especially during prenatal (before birth) development. Choline is considered to be a vitamin-like essential nutrient. The body can make choline, but under certain conditions, the body does not synthesize enough to meet its needs.

good food sources of folate

Leafy green vegetables, liver, legumes, asparagus, broccoli, and oranges asparagus cooked spinach cooked lentils black-eyed peas romaine lettuce fortified cereal & grains cooked turnips cooked broccoli sunflower seeds orange juice cooked beets kidney beans

preformed vitamin A sources

Liver, Fish Fish Oils Fortified Milk Yogurt Eggs

vitamin deficiencies in the U.S. // populations at risk for vitamin deficiency in the U.S.

Many Americans do not consume recommended amounts of E, D, and choline. // Alcoholics Older adults Hospitalized people (long-term) Anorexia nervosa Certain gastrointestinal disorders Rare metabolic conditions

vitamin absorption

Most absorption occurs in small intestine. Absorption is not 100% efficient. Absorption generally increases when more of the vitamin is needed: Growth (e.g., during infancy and adolescence) Pregnancy Lactation (milk production) Fat-soluble vitamins are absorbed with dietary fat. Some fat is needed in the diet. Diseases that affect the GI tract can reduce vitamin absorption. Cystic fibrosis (CF) interferes with fat digestion and fat-soluble vitamin absorption. People with CF and other intestinal diseases may need to take supplemental sources of vitamins.

coenzyme action of water soluble vitamins

Most function as components of specific coenzymes Coenzymes: small molecules that regulate chemical reactions by interacting with enzymes Coenzyme Action Many enzymes require coenzymes to function. Once activated, the enzyme-coenzyme complex enables the reaction to occur.

sources of vitamins

Natural Sources: Plants, animals, fungi, and bacteria Synthetic: Made in laboratories by chemists Synthesized by microbes in laboratories

two exceptions to equal activity of natural and synthetic vitamins

Natural vitamin E: greater activity than synthetic Synthetic folic acid: greater activity than natural

folate affect on neural tube defects

Neural Tube Defects During the first few weeks after conception, the neural tube forms. Neural tube develops into the brain and spinal cord. Folate-deficient pregnant women are at risk of giving birth to infants with neural tube defects. Anencephaly Brain does not form properly. Spina bifida Spine does not form properly before birth and fails to enclose the spinal cord.

major functions of vitamin A

Normal vision and reproduction Cellular growth Immune system activity Epithelial cell production and maintenance

Vitamin B-6 (Pyridoxine-general vitamin name and form added to foods) Functions

Part of coenzyme needed for amino acid, carbohydrate, and fat metabolism Helps to remove the nitrogen group from certain amino acids for use with another amino acid Co-enzyme in conversion of homocysteine to cysteine Synthesis of neurotransmitters Co-enzyme in the synthesis of hemoglobin Co-enzyme in the synthesis of white blood cells

functions of folic acid

Part of coenzyme tetrahydrofolic acid (THFA) THFA involved in DNA and amino acid metabolism Conversion of homocysteine to methionine

vitamin B-12 cyanocobalamin functions

Part of coenzymes needed for: Folate metabolism Maintenance of myelin sheaths that insulate neurons

Niacin (Formally B-3) Functions

Part of two coenzymes that participate in at least 200 reactions

vitamin E food sources

Plant oils Asparagus tomatoes green leafy vegetables eggs margarine whole grains nuts seeds The content of vitamin E in food depends on how the food was harvested, processed, stored and cooked. Vitamin E is destroyed by oxygen, metals, light and repeated use in deep-fat-frying.

vitamin E as medicine?

Questionable Benefits Recent studies did not support taking vitamin E (alpha-tocopherol) supplements to reduce risk of heart attacks, cancer, macular degeneration, and cognitive decline. Future studies using other forms of vitamin E may provide scientific support for taking the vitamin to prevent or treat certain diseases.

folate adequacy and deficiency

RDA = 400 mcg DFE/day (dietary folate equivalents per day) Folate Deficiency Lack of folate affects cells, such as red blood cells (RBC), that rapidly divide. Mature RBCs do not have nuclei and live ~ 4 months. Without folate, RBC precursor cells enlarge, but cannot divide. (DNA is needed for division.) Bone marrow releases some large, immature, abnormal RBCs with nuclei (megaloblasts) into the blood stream. Fewer mature red blood cells are made ; the capacity to carry oxygen is decreased causing folate deficiency anemia (megaloblastic anemia or macrocytic anemia)

dietary adequacy of vitamin A

RDA: 700 - 900 mcg RAE(Rectinol activity equivalents) Replaces another expression of measurement- International Units (IU)

vitamin D is needed for

Regulates the metabolism of calcium & phosphorus Regulates the production & maintenance of healthy bones Parathyroid hormone (PTH) Released when blood calcium levels drop Stimulates kidneys to increase active vitamin D production & decrease urinary calcium excretion Maintaining Normal Blood Calcium Levels

vitamin A retinoids

Retinoids (preformed A) ; There are three different forms of vitamin A : retinol, retinal and retinoic acid and collectively the compounds are known as retinoids. Foods derived from animal foods such as fish oils, eggs,and butter provide the preformed vitamin A. The Preformed vitamin A is stored in the liver.

provitamin A carotenoid sources

Sources: dark green and yellow-orange vegetables and some fruits Sweet potato Spinach Mango Carrots Acorn squash Kale Broccoli Cantaloupe Peaches Apricots

vitamin B-12 (cyanocobalamin)

Synthesized by microorganisms such as bacteria, fungi, and algae. Animals must obtain the vitamin B-12 from these sources. Natural food B-12 is bound to proteins preventing its absorption. The synthetic B-12 is not protein bound. As the food enters the stomach, vitamin B-12 is released from the protein by hydrochloric acid. Vitamin B-12 binds with the intrinsic factor and is absorbed in the ilium of the small intestine. Intrinsic factor is a glygoprotein produced in the stomach. Vitamin B-12 is transported through the bloodstream to the liver via the hepatic portal vein. The liver stores about 50% of the vitamin.

vitamins are micronutrients. how much do we need?

The amount of vitamins needed to prevent deficiency is small. Generally humans require a total of about 1 ounce (28 grams) of vitamins for every 150 pounds(70 kilograms) of food consumed.

water soluble vitamins

Thiamin(thiamine, B-1 Riboflavin (B-2) Niacin(B-3), nicotinamide, nicotinic acid B-6 (pyridoxine) B-12 (cobalamin, cobalamine Biotin(H) Pantothenic acid (B5) Folate (Folic acid, Folacin) C (ascorbic acid)

upper level for B-6

Upper level is 100 milligrams/day due to risk of developing nerve damage.

Folic Acid. B-6, and B-12 As Medicine?

Use: Lowers blood homocysteine levels when taken together (folate, B-12, and B-6) CVD Recent studies of subjects with CVD suggest folic acid supplements do not reduce risk of having another heart attack. Alzheimer's disease May be a relationship between mild cognitive impairment and folate deficiency or elevated blood homocysteine—more research is needed.

vitamin B-6 as medicine?

Uses Claims include help for symptoms of PMS and carpal tunnel syndrome. Weak or no scientific support for claims Side effects of high doses Severe sensory nerve damage Walking difficulties Numbness of hands and feet Because of side effects, not recommended for treating PMS

vitamin C as medicine?

Uses Does not prevent common cold but may reduce severity of the infection Reduces oxidation of LDL cholesterol More research needed to determine whether high doses help reduce CVD risk More research needed to determine whether vitamin C helps reduce cancer risk or aids in cancer treatment Beyond the Common Cold Some studies indicate that vitamin C may: Lower CVD risk by reducing oxidation of LDL Works with vitamin E to lower risk of Alzheimer's disease Interferes with certain cancer-fighting medications

niacin as medicine?

Uses Given to lower LDL cholesterol and raise HDL cholesterol Side effects Flushing of skin on face and chest, itchy skin, GI tract upset, and liver damage

vitamin E adequacy, deficiency, and upper limit intake

VItamin E Adequacy RDA: 15 mg/day of alpha-tocopherol the most active form Vitamin E Deficiency Causes cell membranes to break down Cell membranes of RBC to break apart (Hemolysis );Due to oxidation of polyunsaturated fatty acids in cell membrane Vitamin E Toxicity Upper Limit (UL) 1000 mg/day of alpha-tocopherol Excess may interfere with vitamin K's role in blood clotting. Megadoses of vitamin E may cause hemorrhage in people taking vitamin K or taking anticoagulants such as aspirin, or coumadin.

vitamin C (ascorbic acid)

Vitamin C facilates chemical reactions as a cofactor. It is important in cellular functions and donates electrons. Vitamin C is not part of a conenzyme as the B vitamins.

which vitamins are susceptible to loss in fruits, other foods?

Vitamin C, thiamin, and folate are easily destroyed by improper storage and preparation practices. Niacin and vitamin D tend to be very stable.

how vitamin D affect blood calcium levels

Vitamin D plays a major role in the homeostatic control of calcium and phosphorus blood levels in the human body. Any decrease in calcium blood levels activates the parathyroid gland to release parathyroid hormone(PTH); PTH stimulates the active transport of calcium and phosphorus across the intestinal mucosa. Then 1, 25 dihydroxyvitamin D increases calcium reabsorption from the kidney and stimulate the movement of calcium from the bones. As the plasma level of calcium rises to normal the synthesis of 1, 25 dihydroxyvitamin D slowly decreases. If the plasma calcium levels rise too much, calcitonin, a hormone secreted by the thyroid gland will reverse the action of the PTH

vitamin enrichment, vitamin fortification

Vitamin Enrichment Addition of specific amounts of thiamin, riboflavin, niacin, folic acid, and the mineral iron to refined flour & milled grains Grains lose considerable amounts of their natural vitamin/mineral contents during refinement Vitamin Fortification Addition of one or more nutrients to a wide array of commonly eaten processed foods during their manufacturing

how vits differ from carbs, fats, proteins

Vitamins are: Organic No Calories Micronutrients Foods contain very small amounts (milligrams or micrograms) Carbhydrates, Fats, Proteins are: Organic Provides Calories Macronutrients Foods contain relatively large amounts Amounts measured in (grams)

do vitamins supply any calories?

Vitamins do not supply energy, but many participate in the chemical reactions that release the energy stored in macronutrients.

B-6 content in selected foods

animal products ready-to-eat breakfast cereals(fortified) potatoes milk bananas cantaloupes broccoli spinach avocado watermelon sunflower seeds acorn squash

vitamin B-12 food sources

beef liver salmon sardines tuna meat milk and milk products poultry eggs fish shellfish Fortified foods such as soy and ready-to-eat cereals

niacin food sources

enriched cereals beef liver tuna salmon poultry pork mushrooms

vitamin K food sources

liver some plant oils-soybean and canola oils calcium supplements green vegetables-kale, turnip greens, spinach, Brussels sprouts, asparagus, broccoli lettuce synthesized by bacteria in the small intestine

riboflavin food sources

mild and milk products enriched grains and cereals meat eggs asparagus broccoli greens

thiamin (formally called B-1) functions

part of coenzyme involved in release of energy from carbohydrates Metabolism of certain amino acids Synthesis of neurotransmitters

thiamin food sources

pork products whole grains (wheat germ) enriched grains green beans milk orange juice organ meats peanuts dried beans seeds

vitamin D synthesis

primarily regarded as a hormone. It is a fat soluble vitamin made from cholesterol. The cholesterol -like substance in the cells of the skin is converted to prohormone (vitamin D3) as the skin is exposed to the ultraviolet rays from the sun or tanning beds. It is then converted in the liver to 25-hydroxyvitamin D and then in the kidney to the active form of vitamin D known as 1, 25 dihydroxyvitamin D. This is the active hormone form. 1, 25 dihydroxyvitamin D can increase deposits of calcium and phosphates in the bones, decrease excretion from the kidneys and stimulate the absorption of calcium and phospates in the intestinal system.