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Chapter 6 Vitamins 1 Characteristics of Vitamins 1. Very small amounts are needed by the body and very small amounts are in foods. 2. The roles they play in the body are very important. 3. Most vitamins are obtained through food. Some are made by bacteria in the intestine and one is made in the skin. 4. There is no perfect food that contains all the vitamins in the right amount. 2 Characteristics of Vitamins (cont’d) 5. Vitamins do not contain kcalories, but they are involved in extracting energy from the macronutrients. 6. Some vitamins in foods are precursors. 7. Vitamins are classified according to how soluble they are in fat or water. 3 Fat-Soluble Vitamins Fat-soluble vitamins are generally found in foods containing fats and are stored in the body either in the liver or in adipose tissue until needed. Excessive intake of A or D causes them to be stored and can be undesirable. Vitamin D, when taken in excess, is the most toxic of all the vitamins. Fat-soluble vitamins are absorbed and transported around the body like other fats. If anything interferes with fat absorption, these vitamins may not be absorbed. 4 Forms of Vitamin A Retinoids Retinol Retinal Retinoic Acid 5 Carotenoids Beta-carotene Retinol 6 Functions of Vitamin A Essential for health of the cornea (clear membrane surrounding eye)- deficiency causes xerosis and eventually xerophthalmia Essential for retina of eye – deficiency causes night blindness 7 Functions of Vitamin A (cont’d.) Needed to make and maintain the epithelial cells that form the protective linings of your lungs, GI tract, urinary tract, and other organs Also essential to make and maintain epithelial cells that produce mucus (protects cells) Role in reproduction, growth and development, bone growth and teeth developing in children Proper functioning of immune system Healthy skin 8 Beta Carotene A precursor of vitamin A Functions as an antioxidant in the body – a compound that combines with oxygen to prevent oxygen from oxidizing or destroying important substances The most abundant carotenoid Rich sources: Deep green vegetables – spinach Deep orange fruits and veggies – carrots 9 Retinol Preformed vitamin A Found in animal products such as: Liver Vitamin A-fortified milk Eggs Fortified cereals Butter and margarine 10 Measurement of Vitamin A Measured in retinol activity equivalents (RAE) One RAE = 1 microgram retinol 12 micrograms beta-carotene 24 micrograms of other vitamin A precursors 11 Vitamin A: Deficiency and Toxicity Deficiency is of most concern in developing countries where it causes night blindness, blindness, poor growth, and other problems Prolonged use of high doses of preformed vitamin A may cause hypervitaminosis A Hair loss Bone pain Skin problems Liver damage Nausea/diarrhea 12 Vitamin D When ultraviolet rays shine on your skin, a cholesterollike substance is converted into a precursor of vitamin D and absorbed in the blood. Over the next few days, the precursor is converted to vitamin D3 (cholecalciferol). Vitamin D3 is converted into its active form – a hormone – by enzymes in the liver and then the kidney. 13 Functions of Vitamin D Maintains blood calcium levels by: Increasing calcium absorption in the intestine Decreasing the amount of calcium excreted by the kidney Pulling calcium out of the bones Blood calcium levels must be kept high so there is enough calcium to build bones and teeth, contract muscles, and transmit nerve impulses 14 Sources of Vitamin D Vitamin D fortified milk and cereals Fatty fish 15 Vitamin D: Deficiency and Toxicity Deficiency in children: rickets Deficiency in adults: osteomalacia Toxicity: Vitamin D is most toxic of all vitamins About 4 to 5x the Adequate Intake: symptoms will include nausea, vomiting, diarrhea, fatigue, and confusion; can lead to calcium deposits in the heart, blood vessels, and kidneys. 16 Functions of Vitamin E Antioxidant in the cell membrane and other parts of cell. Protects vitamin A from oxidation. Important for healthy immune system, and nervous tissues. 17 Food Sources of Vitamin E Widely distributed in plant foods: Vegetable oils, margarine, and shortening Salad dressing made from vegetable oils Seeds and nuts Whole-grain breads and cereals 18 Vitamin K Essential role in producing blood-clotting factors, such as prothrombin. Needed to make an important protein used to form bone. Bacteria in the intestines produce a form of vitamin K. Food sources: liver, green leafy vegetables, broccoli, vegetable oils 19 Water-Soluble Vitamins Includes Vitamin C and B-complex vitamins. B vitamins work in every cell as coenzymes. Only small amounts of water-soluble vitamins are stored in body (except B6 and B12). American adults take in too little vitamin C. Excessive supplementation of certain watersoluble vitamins can cause toxic effects. 20 Functions of Vitamin C Needed to make collagen, a fibrous protein that is part of skin, bone, teeth, ligaments, and other connective structures. (Vitamin C acts like Cement). Needed to make some hormones, such as thyroxine, and some neurotransmitters. Needed for immune system. Antioxidant (like vitamin E and betacarotene). Helps iron to be absorbed. 21 Food Sources of Vitamin C Citrus fruits Bell peppers Kiwi fruit Strawberries Tomatoes Broccoli Potatoes Fortified juices and cereals 22 Vitamin C: Deficiency and Toxicity Deficiencies resulting in scurvy are rare. Situations that require additional vitamin C: Pregnancy, lactation, growth, fever, infections, burns, surgery, smoking. UL is 2 grams: Over 2 grams causes gastrointestinal symptoms. High levels interfere with certain medical tests. 23 Thiamin, Riboflavin, and Niacin All play key roles as part of coenzymes in energy metabolism: they are essential to release energy from carbohydrates, fats, and proteins. All are needed for normal growth. Thiamin also plays a role in nerve function. Riboflavin is needed to help form vitamin B6 coenzyme and to make niacin in the body. 24 Food Sources of Thiamin, Riboflavin, and Niacin Thiamin – pork, sunflower seeds, wheat germ, peanuts, dry beans, whole-grain and enriched breads and cereals. Riboflavin – Milk and milk products, organ meat, whole-grain and enriched breads and cereals. Niacin – Meat, poultry, fish, organ meats, whole-grain and enriched breads and cereals, peanut butter. 25 Tryptophan (Amino Acid) Found in Protein Foods is Converted to Niacin in the Body Amino Acid Tryptophan Niacin 26 Functions of Vitamin B6 Important role as part of a coenzyme involved in carbohydrate, fat, and protein metabolism. In its coenzyme form, B6 is particularly crucial to protein metabolism. Used to make red blood cells. Used to break down glycogen to glucose. Used to convert tryptophan to niacin. Used to make neurotransmitters. Important to the immune system. 27 Sources of Vitamin B6 Meat, poultry, fish Not as well absorbed from plant foods Potatoes Some fruits (bananas and watermelons) Some leafy green vegetables (broccoli and spinach) Fortified ready-to-eat cereals 28 Vitamin B6: Deficiency and Toxicity Deficiency: may occur in women and older adults Deficiency symptoms: fatigue, depression, irritability More than 2 grams daily for 2 months or more than 200 mg daily for longer can cause irreversible nerve damage and symptoms such as numbness in hands and feet and difficulty walking B6 is stored in the muscles 29 Functions of Folate Part of coenzymes required to make DNA, the genetic material contained in every cell. Therefore needed to make all new cells, especially those that need to be replenished frequently: RBC, WBC, and digestive tract cells. Needed to form neurotransmitters in the brain. Needed for amino acid metabolism. 30 Sources of Folate Green leafy vegetables (such as spinach) Legumes Orange juice Fortified breads and ready-to-eat cereals Much folate is lost during food prep and cooking 31 Dietary Folate Equivalents (DFEs) RDA for folate is measured in micrograms of DFEs. DFEs take into account the amount of folate absorbed from natural and synthetic sources. Synthetic folate is used in fortified foods such as breads and in supplements. Synthetic folate is absorbed at 1.7 times the rate of naturally-occurring folate. 32 Folate Deficiency Deficiency causes megaloblastic anemia – RDC are large and immature. Other deficiency symptoms: digestive tract problems such as diarrhea, mental confusion, and depression. During earliest weeks of pregnancy, women need folate because a deficiency can cause neural tube defects. Some medications interfere with the normal use of folate in the body. 33 Functions of Vitamin B12 Convert folate into its active forms so that it can make DNA. Also functions as part of a coenzyme needed to make new cells and DNA. Helps in the normal functioning of the nervous system by maintaining the protective cover around nerve fibers. 34 Sources of Vitamin B12 Only animal foods. Meat Poultry Fish and Shellfish Eggs Milk Milk Products Vegetarian concerns 35 Vitamin B12 Deficiency Deficiency is usually due to problem with absorption – lack of intrinsic factor or lack of hydrochloric acid – both are more so problems as you get older. Pernicious anemia develops when B12 is not properly absorbed. Symptoms: Macrocytic anemia Extreme weakness and fatigue Nervous system problems – balance, numbness, confusion 36 Pantothenic Acid and Biotin Both are needed to release energy from carbohydrates, fats, and proteins. Pantothenic acid is also needed to make fatty acids. Biotin is also involved in the metabolism of carbohydrates, fats, and protein. 37 Sources of Pantothenic Acid & Biotin Both pantothenic acid and biotin are widespread in foods. Pantothenic acid: Fortified cereals, beef, poultry, mushrooms, potatoes, tomatoes. Biotin: Egg yolks. (Intestinal bacteria make considerable amounts of biotin.) 38 Choline Choline can be made in the body in small amounts. Needed to make the neurotransmitter acetylcholine and the phospholipid lecithin (major component of cell membranes). Widespread in foods. Choline is a conditionally essential nutrient. 39 Vitamin-like Substances Carnitine, lipoic acid, inositol, and taurine are needed for normal metabolism but the body makes enough so they are not vitamins. Some are added to formula for infants. Other substances promoted as vitamins, such as pangamic acid or bioflavonoids, are clearly not vitamins. 40 Ingredient Focus: Fruits & Veggies Low in kcalories Low or no fat (except avocados) No cholesterol Good sources of fiber Excellent sources of vitamins and minerals Low in sodium (except some canned veggies) 41 Food Facts: How Food Processing, Storage, Preparation, and Cooking Affect Vitamin and Mineral Content 1. Buy fresh, high-quality food. 2. Inspect fresh fruits and veggies for appropriate color, size, and shape. 3. Store fresh fruits and veggies in the refrigerator (except bananas, avocados, potatoes, and onions). 4. Minimize storage times and store canned goods in a cool place. 5. Wrap up fresh fruits and veggies in the refrigerator to decrease exposure to air. 42 Food Facts: How Food Processing, Storage, Preparation, and Cooking Affect Vitamin and Mineral Content (cont’d.) 6. Wash fruits and veggies when ready to use. 7. Cut vegetables up no more than necessary. 8. Keep skins of fruits as much as possible. 9. Steaming, microwaving, and stir-frying are good choices. 10. Frying can destroy vitamins. 11. Never use baking soda. 43 Food Facts: How Food Processing, Storage, Preparation, and Cooking Affect Vitamin and Mineral Content (cont’d.) 11. Broiled or roasted meats retain more B vitamins than meats that are braised or stewed. 12. Use the cooking water from vegetables and the drippings from meat (after skimming off the fat) to prepare soup and gravy. 13. Prepare foods close to the time of service. 14. Don’t keep milk in glass containers. 44 Functional Foods and Phytochemicals Functional foods: Foods supplemented with ingredients thought to help prevent diseases or to improve health. Margarine with an ingredient to lower cholesterol Drinks with herbs such as ginseng Phytochemicals: Substances such as beta- carotene that are found largely in fruits and veggies and that seem to be helpful in preventing cancer and/or heart disease when consumed regularly 45 Phytochemicals Phytochemical Names Good For Food Sources Lutein and Zeaxanthin Healthy eyesight Turnip, collard, and mustard greens; kale; spinach; lettuce; broccoli; green peas; kiwi; honeydew melon. Indoles Anti-cancer Broccoli, cabbage, Brussels sprouts, bok choy, arugula, Swiss chard, turnips, rutabaga, watercress, cauliflower, kale. Healthy heart, healthy anti-cancer Oranges, grapefruit, lemons, tangerines, clementines, peaches, papaya, apricots, nectarines, pears, pineapple, yellow raisins, yellow pepper. Green Vegetables & Fruits Yellow/Orange Vegetable & Fruits Bioflavonoids 46 Phytochemicals (cont’d) Red Vegetables and Fruits Anthocyanins Healthy circulation, healthy nerve function, anti-cancer Raspberries, cherries, strawberries, cranberries, beets, apples, red cabbage, red onion, kidney beans, red beans. Anthocyanins Healthy circulation, healthy nerve function, anti-cancer Blueberries, purple grapes, blackberries, black currants, elderberries. Phenolics Healthy cells, anticancer. Raisins, prunes, plums, eggplant. Healthy immune system, healthy cholesterol levels, anti-cancer Garlic, onions, leeks, scallions, chives. Blue/Purple Vegetables and Fruits White Vegetables and Fruits Allium and Allicin Source: National Cancer Institute 47 Copyright ©2007 John Wiley & Sons, Inc. Clip art images may not be saved or downloaded and are only to be used for viewing purposes. 48