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Vitamins ◦ ◦ ◦ ◦ ◦ Organic compounds Vital to life Indispensable to body functions Needed in minute amounts Noncaloric essential nutrients Two classes of vitamins: Fat-soluble: A,D, E, K ◦ In general, absorbed into the lymph ◦ Travel in blood in association with protein carriers ◦ Stored in the liver or with other lipids in fatty tissues; some can build up to toxic concentrations Water-soluble: B vitamins, vitamin C ◦ ◦ ◦ ◦ ◦ Absorbed directly into blood stream Travel freely in blood stream Most are not stored to any great extent Excess excreted in urine Lower risk of toxicity than fat-soluble vitamins A, D, E, K ◦ Found in fats and oils of foods ◦ Require bile for absorption ◦ Stored in liver and fatty tissues until the body needs them Body can survive weeks of consuming foods that lack these vitamins ◦ As long as a diet as a whole provides average amounts that approximate recommended intakes ◦ Excess vitamins A and D from supplements can easily reach toxic levels Deficiency is likely when diet is consistently Fat malabsorption diseases can cause loss in Extraordinarily-low-fat diets low in fat-soluble vitamins dissolved undigested fat Functions: ◦ ◦ ◦ ◦ ◦ ◦ Vision Maintenance of body linings and skin Immune defenses Growth of bones and the body Normal cell development Reproduction Excessive beta-carotene will not cause vitamin A toxicity ◦ However, it can cause people to turn a bright yellow due to deposition in subcutaneous fat Roles of vitamin D ◦ Regulation of blood calcium and phosphorus levels Often at a genetic level When more calcium is needed vitamin D acts to raise blood calcium levels Draws calcium from bone Promotes calcium absorption Promotes calcium retention by the kidneys ◦ Functions as a hormone ◦ Plays a role in the brain, heart, stomach, pancreas, skin, reproductive organs, some cancer cells, stimulates cell maturation Deficiency promotes: ◦ High blood pressure, some cancers, type 1 diabetes, heart disease, rheumatoid arthritis, multiple sclerosis Too Little Vitamin D - A Danger to Bones ◦ Rickets Vitamin D deficiency disease in children Characterized by abnormal bone growth Bowed, or knock-knees, outward-bowed chest, knobs on ribs © 2006 Thomson-Wadsworth Older individuals may have painful joints and muscles due to low vitamin D levels Osteomalacia, the adult form of rickets ◦ Characterized by an overabundance of unmineralized bone protein ◦ Most often occurs in women with low calcium intake and little exposure to the sun and who go through repeated pregnancies and periods of lactation Too Much Vitamin D - A Danger to Soft Tissue ◦ Most potentially toxic of all vitamins ◦ Toxicity symptoms include: appetite loss, nausea, vomiting, increased urination, increased thirst, severe form of psychological depression due to effects on the central nervous system If overdoses continue: dangerously high blood calcium level, forcing calcium to be deposited in soft tissues Not essential in the sense that the body can make all it needs with the help of sunlight How Can People Make a Vitamin from Sunlight? ◦ Most people rely on exposure to sunlight to maintain adequate vitamin D nutrition ◦ UV exposure to a cholesterol compound in the skin transforms it into a vitamin D precursor which is absorbed into the blood Skin synthesis of vitamin D poses no risk of toxicity ◦ The sun itself begins breaking down excess vitamin D made in the skin ◦ Sunbathers are at risk of skin damage and skin cancer Sunscreens with SPFs of 8 or above can reduce these risks, but they also prevent vitamin D synthesis In most places, during warmer months, just being outdoors when the sun is overhead, even in lightweight clothing, promotes sufficient skin synthesis of vitamin D Factors affecting sun exposure and vitamin D synthesis: ◦ Skin color, air pollution, city living, clothing, geography, indoor lifestyle, season, sunscreen, time of day ◦ African and Mexican Americans, may border on vitamin D insufficiency Sources: ◦ Small amounts from butter, cream, fortified margarine ◦ Fortified milk, sunlight ◦ Only two fortified plant sources exist: margarines and certain cereals Consists of four tocopherol compounds ◦ Alpha, beta, gamma, delta ◦ Alpha-tocopherol is the standard for vitamin E activity The Extraordinary Bodyguard ◦ Antioxidant ◦ Damage that results when free radicals formed during normal metabolism disrupt the structure of cellular lipids, DNA, proteins Free radical activity may lead to cancer, heart disease, or other diseases Vitamin E is preferentially oxidized, thus protecting cells Supplements do not provide health benefits However, supplements may improve the immune response in healthy elderly people Vitamin E Deficiency ◦ Wide variety of symptoms in laboratory animals, most symptoms not reproduced in humans ◦ Vitamin E is widespread in food, making it difficult to create a vitamin E-deficient diet ◦ Body stores large amounts in fatty tissues ◦ Cells recycle vitamin E Infants born before the transfer of vitamin E from the mother to the infant ◦ Potential anemia Adults: loss of muscle coordination and reflexes with impaired movement, vision, and speech Associated with fat malabsorption diseases ◦ disease or injury to the liver, gallbladder, pancreas Low intakes likely when extremely-low-fat diets are consumed for years Vitamin E is destroyed by food processing and heating Chronically low intake may play a role in other diseases ◦ Low body stores of vitamin E and selenium promote viral virulence No toxicity from food sources Ordinary supplemental doses over a period of months do not seem to induce toxicity In humans, occasional reports of breast soreness in women, nausea, intestinal distress, fatigue, emotional distress , and other vague complaints Large doses may increase the effects of anticoagulant medications Brain hemorrhages may occur in smokers taking 50 milligrams/day for over 6 years Widespread in foods ◦ Most raw oils ◦ 20% of dietary vitamin E comes from vegetable oils ◦ 20% from fruits and vegetables None of which qualify as a good source ◦ 15% from fortified cereals and other grain products Smaller amounts from meat, poultry, fish, eggs, milk products, nuts, seeds Wheat germ is a good source Animal fats have almost no vitamin E Functions: ◦ Synthesis of blood clotting proteins Does not improve clotting in those with diseases such as hemophilia Interferes with function of blood thinners ◦ Synthesis of normal form of bone proteins that bind minerals to bone Adequate intake may reduce risk of hip fracture At birth newborns are given a dose of vitamin K to hold them until vitamin K-producing bacteria establish themselves in their intestinal tract © 2006 Thomson-Wadsworth Sources: ◦ Leafy green vegetables Cooked spinach and collard greens average 300 micrograms/3 ounces Lettuce, broccoli, other members of the cabbage family average 100 micrograms/3 ounces ◦ Intestinal bacteria, canola and soybean oils, fortified cereals ◦ 1 egg and 1 cup of milk: 25 micrograms each Deficiency ◦ Unlikely in adults Even if they seldom eat vitamin K-rich foods ◦ At risk: Newborns Those who have taken antibiotics that kill the beneficial, along with the harmful, bacteria in their intestinal tract Low bile production Vitamin C and the B Vitamins ◦ Cooking and washing with water leaches them out of food ◦ Easily absorbed ◦ Excess easily excreted in urine ◦ Some can remain in lean tissues for 1+ months Toxicity ◦ Never from food ◦ Can occur from the large doses concentrated in some vitamin supplements Though the usual result will be to have expensive urine The Work of Vitamin C ◦ Maintenance of connective tissues Formation and maintenance of collagen Component of bones, teeth, skin, tendons, scar tissue, capillaries Scurvy ◦ Vitamin C (ascorbic acid) deficiency ◦ Hazard of long distance seagoing journeys of 200+ years ago ◦ To avoid scurvy, British sailors were given lime juice Deficiency Symptoms ◦ Most scurvy symptoms are due to the breakdown of collagen Loss of appetite, growth cessation, loose teeth, swollen ankles and wrists, tiny red spots in the skin where blood has leaked out of capillaries, anemia Antioxidant ◦ Protects substances found in foods and the body by being oxidized itself ◦ Some oxidized vitamin C is lost and must be replaced by the diet ◦ In the intestines, protects iron from oxidation Thus promoting its absorption In the blood ◦ Protects blood from oxidation ◦ Protects and recycles Vitamin E Supplements seem useless against heart disease, cancer, other diseases In test tubes, high concentrations of vitamin C act as a prooxidant ◦ Activating oxidizing elements, such as iron and copper ◦ One study of men given 500 milligrams/day showed an increase in markers of oxidation Risk of scurvy in the U.S. is low, with the exception of ◦ Some elderly people Low intakes of fruits and vegetables combined with a poor appetite lead to low vitamin C intakes ◦ People addicted to alcohol or other drugs ◦ Infants fed cow’s milk who do not receive vitamin C in formula, fruit juice, or other sources Breast milk and infant formula supply enough vitamin C Studies are yet to conclusively show that vitamin C can prevent or reduce the severity of colds One group of researchers have found the following: ◦ Daily dosages of vitamin C, taken regularly, do not prevent colds The same group of researchers have also found ◦ Some small benefit from vitamin C in high doses (1 gram) taken at the onset of a cold ◦ This may shorten the duration of colds by about 1.5 days and reduce the severity of symptoms by about 40% The effect may be greater in children then adults In adults, doses near the UL (2 grams/day) may be required to produce any effect Both active and passive smoking introduce oxidants that deplete vitamin C ◦ Intake recommendations are set high Males: 110 milligrams Females: 105 milligrams ◦ Vitamin C cannot protect against the damage caused by exposure to tobacco smoke Food Sources of Vitamin C ◦ 300 milligrams: 1 cup orange juice for breakfast, salad for lunch, stalk of broccoli, a potato for dinner ◦ Vitamin C in fruits and vegetables are prone to destruction by heat and oxygen Fresh, raw, and quickly cooked are best Store properly and consume promptly © 2006 Thomson-Wadsworth Role ◦ Energy metabolism ◦ Nerve processes and tissue response Deficiency: beriberi “I can’t, I can’t” ◦ Loss of sensation in the hands and feet, muscular weakness, advancing paralysis, abnormal heart action ◦ Wet beriberi Characterized by edema ◦ Dry beriberi No edema Acute © 2006 Thomson-Wadsworth Deficiency: Wernicke-Korsakoff Syndrome ◦ Alcohol abuse with severe thiamin deficiency ◦ Alcohol displaces food in the diet, impairs thiamin absorption, promotes thiamin excretion in the urine Symptoms: ◦ Apathy, irritability, mental confusion, disorientation, loss of memory, jerky eye movements, staggering gait Treatment: thiamin injection Sources ◦ Small amounts in many foods ◦ Pork products, leafy green vegetables, whole grain cereals, legumes ◦ DRI: Men: 1.2 mg/day Women: 1.1 mg/day Higher if pregnant or lactating © 2006 Thomson-Wadsworth Role ◦ Energy metabolism of all cells Deficiency ◦ Likely when thiamin is deficient ◦ May go undetected because thiamin deficiency symptoms are more severe ◦ At risk: Children who lack milk products and meat Perhaps some U.S. elderly ◦ Treatment: A diet that remedies riboflavin deficiencies also remedies a thiamin deficiency Sources ◦ ◦ ◦ ◦ ◦ Milk and milk products Leafy green vegetables Whole-grain breads Fortified cereals Some meats © 2006 Thomson-Wadsworth Role ◦ Energy metabolism Deficiency ◦ Pellagra Diarrhea Dermatitis Dementia Death At risk for pellagra: ◦ Poorly nourished people living in urban slums Particularly those with alcohol addiction ◦ Still common in parts of Africa and Asia Sources ◦ Tryptophan, which is abundant in almost all proteins, can be converted to niacin Thus a person eating adequate protein will not be deficient in niacin ◦ Niacin in the diet is stated in terms of niacin equivalents (NE) Accounts for conversion of tryptophan to niacin Toxicity ◦ Large doses of a form of niacin may be a part of a treatment to lower blood lipids associated with cardiovascular disease Do not try this at home ◦ Large doses of niacin can injure the liver, cause peptic ulcers, cause vision loss Certain forms of niacin supplements in amounts 2x-3x the DRI can cause niacin flush: ◦ Dilation of the capillaries of the skin with perceptible tingling that, if intense, can be painful Role ◦ DNA synthesis ◦ Metabolism of several amino acids Deficiency ◦ Because immature red and white blood cells and cells of the GI tract divide rapidly, they are most vulnerable to a deficiency ◦ Anemia Related to anemia of vitamin B12 malabsorption ◦ Diminished immunity ◦ Abnormal digestive function Deficiency may result from ◦ ◦ ◦ ◦ Inadequate intake Illnesses that impair folate absorption Increased excretion Medications that interact with folate, or otherwise increase the body’s need With deficiency, some evidence for increased ◦ Cardiovascular risk ◦ Colon cancer risk ◦ Cervical cancer risk Neural tube birth defects ◦ Range from slight problems in the spinal cord to mental retardation ◦ Severely diminished brain size ◦ Death shortly after birth ◦ Arise in the first few days or weeks of pregnancy Most women eat too few fruits and vegetables to supply even 50% of the folate needed to prevent such birth defects All enriched grain products are fortified with folic acid ◦ An especially absorbable synthetic form of folate ◦ Since fortification began, folate intakes have increased and there has been an almost 25% drop in the national incidence of neural tube defects It is expected that there will also be declines in some other birth defects and miscarriages Toxicity ◦ UL for synthetic folate from supplements and enriched foods is 1,000 micrograms/day for adults ◦ Folate can mask vitamin B12 deficiency ◦ Excess folate may be antagonistic to the actions of some anticancer drugs Sources ◦ Leafy green vegetables ◦ Fresh, uncooked vegetables and fruits The heat of cooking and oxidation that occurs during storage destroy much of the folate in foods ◦ Eggs contain folate ◦ Orange juice and legumes contain folate Contain factors that may interfere with folate absorption ◦ Milk may enhance folate absorption Medications ◦ Of all the vitamins, folate is most likely to interact with medications ◦ Ten major groups of drugs, including antacids and aspirin and its relatives, oral contraceptives, anticonvulsants, smoke interfere with the body’s use of folate Occasional use of these drugs is okay Frequent users need to pay attention to their folate intake Role Deficiency Sources ◦ Vitamin B12 is activated by folate ◦ Folate is activated by vitamin B12 ◦ Maintenance of the sheaths that surround and protect nerve fibers ◦ Damaged nerve sheaths ◦ Creeping paralysis ◦ General malfunctioning of nerves and muscles ◦ Foods of animal origin ◦ Not in foods from plants Deficiency results in failure of folate to make red blood cells ◦ Therefore, a vitamin B12 deficiency causes an anemia (pernicious anemia) identical to that of folate Large, immature red blood cells ◦ Treatment: administration of folate However, this allows the deficiency of B12 to continue undetected At risk ◦ The possibility that folic acid enrichment of grains is masking vitamin B12 deficiencies ◦ Especially among vegetarians and the elderly Individuals who generally depend heavily on grains and consume little or no meat or other animal products ◦ Malabsorption problems The uninformed, strict vegetarian (vegan) is especially at risk ◦ May not show signs of deficiency right away because the body stores up to six years’ worth of the vitamin Pregnant or lactating vegetarian women may put their infant at risk of a vitamin B12 deficiency ◦ Resulting in irreversible nerve system damage Recognized when the infant displays nerve and cognitive problems that can last into childhood All strict vegetarians must be sure to use vitamin B12-fortified products ◦ Vitamin B12-fortified soy drink, supplements Absorption ◦ Requires intrinsic factor A compound made by the stomach The stomach’s acid liberates vitamin B12 from food; intrinsic factor then binds to the vitamin The complex is then absorbed from the small intestine into the blood In later years, many people lose the ability to produce sufficient stomach acidity and intrinsic factor ◦ Leaving them with reduced ability to absorb vitamin B12 Treatment for defective absorption is B12 injections Role ◦ 100+ reactions in the tissues ◦ Needed to convert one kind of amino acid into other nonessential amino acids ◦ Aids in the conversion of tryptophan to niacin ◦ Hemoglobin synthesis ◦ Neurotransmitter synthesis For example, assists in the conversion of tryptophan to serotonin Role (continued) ◦ Assists in release of stored glucose from glycogen Contributing to the regulation of blood glucose ◦ Immune function ◦ Steroid hormonal activity ◦ Fetal brain and nervous system development Deficiency during this stage causes behavioral problems later Deficiency ◦ ◦ ◦ ◦ ◦ ◦ ◦ ◦ ◦ Weakness Psychological depression Confusion Irritability Insomnia Greasy dermatitis Advanced cases of deficiency: convulsions May weaken the immune system Evidence that low intakes may be related to increased risk of heart disease Sources ◦ Protein-rich foods Meats, fish, poultry ◦ Potatoes, leafy green vegetables, some fruits ◦ Legumes and peanut butter Toxicity ◦ Women who took 2+ grams/day for 2+ months in a mistaken attempt to cure PMS symptoms Numb feet Lost sensation in their hands Eventually became unable to walk or work Recovered after they stopped taking the supplements Role ◦ Energy metabolism ◦ Cofactor for several enzymes in the metabolism of carbohydrate, fat, protein Deficiency ◦ Rare diseases ◦ Consumption of 24+ raw egg whites per day, which contain a protein that binds biotin,will result in a deficiency Cooking eggs denatures this protein Sources ◦ Wide spread in foods ◦ Role ◦ Energy metabolism ◦ Coenzyme that plays a role in the release of energy from the energy nutrients ◦ Plays a role in 100+ steps concerned with the synthesis of lipids, neurotransmitters, and hemoglobin Deficiency ◦ Rare diseases Sources ◦ Widespread in foods