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Chapter 8 Vitamins What are Vitamins? Essential organic substances Produce deficiency symptoms when missing from diet Yield no energy Basic functions – Facilitate energy-yielding chemical reactions – Function as co-enzymes Fat-soluble vitamins Water-soluble vitamins Fun Facts Vitamins were named in order of discovery (A, B, C, D, …) Other substances found not to be essential were dropped (e.g., vitamin P) B-vitamins were thought to be one vitamin; turned out to be many (e.g., B1, B2, B3,…) Vital Dietary Components Megadose (>3-10x needs as a starting point) – Proved useful in treating certain conditions Plant and animal foods provide vitamins Most synthesized vitamins work equally well in the body vs natural Scientists believe they have discovered all the vitamins Storage of Vitamins in the Body Fat-soluble – Not readily excreted (except vitamin K) Water-soluble – Generally lost from the body (except vitamins B-6 and B-12) – Excreted via urine Vitamins should be consumed daily – Occasional lapse is harmless Vitamin Toxicity Fat-soluble vitamins (e.g. Vitamin A) – Can accumulate in the body Water-soluble vitamins – Some can cause toxicity Mostly likely due to supplementation Preservation of Vitamins Decreased vitamin content – Improper storage – Excessive cooking >40*C – Exposure to light, heat, air, water, and alkalinity Eat foods soon after harvest (EAT FRESH) Freeze foods not consumed within a few days Blanching destroys enzymes (bacteria) – Slows down vitamin degradation Preservation Tips Fat-Soluble Vitamins Overview Dissolve in organic solvents Not readily excreted – Can cause toxicity Olestra Absorbed along with fat Fat malabsorption (Xenical/Olestra) – May cause deficiency – Cystic fibrosis (Vit. deficiency) Transported with fat – In lipoproteins Xenical Confirming your knowledge What are the fat Soluble vitamins, why (i.e. non polar)? 1 3 2 4 Vitamin A Narrow optimal intake range Preformed – Retinoids – Found in animal products (fish/organ meats) Proformed (proVitamin A) – Carotenoids – Found in plant products – Can be converted to Vit A by the body B carotene Functions of Vitamin A Promote vision – Night blindness Promote growth Prevent drying of the skin and eyes – Xerophthalmia (figure 8-1) & macular degeneration Promote immune function and resistance to bacterial infection Cardiovascular disease prevention (b/c antioxidant) Cancer prevention (antioxidants and other) Acne medication (Retin-A, Accutane) Challenge Question What is the name following compound (which has been shown to reduce prostate cancer risk) and what are good sources? Gann et al., 1999, Cancer Research, 59, 1225 Food Sources of Vitamin A: see: 8-2 Recommended Amounts for Vitamin A g RAE for men 700 g RAE for women Daily Value is 1000 g (RAE) ~ 5000 IU Upper Level is 3000 g, 10,000 IU Much stored in the liver No separate RDA for carotenoids 900 Toxicity of Vitamin A Large intake of vitamin A (preformed) – Over a long period – Use of Accutane and Retin-A ≥ 10,000 IU or 3000 RAE Signs and symptoms – Bone/muscle pain, loss of appetite, skin disorders, headache, dry skin, hair loss, increased liver size, vomiting – Fetal malformation (binds to DNA cell develop.) – Possible permanent damage (infants) – < 3000 IUs/day if pregnant Vitamin D Prohormone Derived from cholesterol Synthesized from sun exposure – Sunscreen SPF >8 decreases synthesis 95% – Expose hands, face, arms 2-3 x/week for 5-10 minutes each time (more for darker skin) Insufficient sun exposure makes this a vitamin Activated by enzymes in liver and kidneys Deficiency can cause disease Activation of Vitamin D Functions of Vitamin D Regulates blood calcium – Along with the parathyroid hormone – Regulates calcium + phosphorus absorption – Reduces kidney excretion of calcium – Regulates calcium deposition in bones Influences normal cell development – Linked to reduction of breast, colon, and prostate cancer Role in Bone Formation Causes calcium + phosphorus to deposit in the bones Strengthens bones Rickets is the result of low vitamin D – Breastfed infants with little sun exposure Osteomalacia (soft bones) – Rickets-like disease in adults – Bones lose minerals and become porous Challenge Question According to the USDA and ODS – Vitamin D is now considered a deficiency in N. American diets – what are the two major reasons? 1. 2. Food Sources of Vitamin D Fatty fish (salmon, herring) Fortified milk (N. fat, Low fat or Whole) Some fortified cereal Adequate Intake (AI) for Vitamin D g/day (200 IU/day) for adults under age 51 5 g/day (400 - 600 IU/day) for older adults 10-15 Supplement if a breastfed – (See physician for details) infant Toxicity Warning Vitamin D can be very toxic, especially in infancy and childhood Upper Level is 50 µg/day Results in – Over-absorption of calcium (hypercalcemia), increase calcium excretion – Calcium deposits in organs (kidneys) & blood vessels – Growth retardation Vitamin E Fat-soluble antioxidant α β δ gamma tocopherol forms Resides mostly on cell membranes Other Functions of Vitamin E Protects double bonds in unsaturated fats Improves vitamin A absorption Deficiency – Breakdown of cell membranes – Hemolysis – Nerve degeneration RDA for adults is 15 mg/day – Many adults are not meeting this goal Food Sources of Vitamin E Toxicity of Vitamin E Upper Level is 1,000 mg/day (supplementary alpha-tocopherol) Upper Level is 1500 IU (natural sources) or 1100 IU (synthetic forms) Adivse mixture of natural tocopherols (vs synthetic sources) (400 IUs) Toxic effects – Inhibit vitamin K metabolism and anticoagulants – Possible hemorrhage – Muscle weakness, headaches, nausea Vitamin E SHOW Vit E video Vitamin K (“Koagulation”) Synthesized by bacteria in the colon (10%) and absorbed (diet) Frequent anti-biotics deficiency. . . Role in coagulation process (fig 8-10) Role in calcium-binding potential Food Sources of Vitamin K Liver Green leafy vegetables Broccoli Peas Green beans Resistant to cooking losses Limited vitamin K stored in the body (<24hr) Adequate Intake for Vitamin K 90 µg/day for women 120 µg/day for men Excess vitamins A and E – Interferes with vitamin K – May cause hemorrhage and fractures Newborns – Routinely injected with vitamin K – Breast milk is a poor source Toxicity unlikely; readily excreted High Levels CVD, prevent reduced clotting Overview of Water-Soluble Vitamins Dissolve in water Generally readily excreted from body Subject to cooking losses Function as coenzymes Participate in energy metabolism 50-90% of B vitamins are absorbed Marginal deficiency more common U.S. Enrichment Act (grains milledloose vitamins . .) – Must be added back (enriched) to products (cereals) Why experts recommend whole grains/brown rice vs Refined grain products Confirming your Knowledge Overview of Water-Soluble Vitamins What are the water soluble vitamins and why (i.e. polar) ? (4) (3) (2) (1) (5) (6) (9) (7) (8) Overview of Water-Soluble Vitamins Participate in energy metabolism Thiamin Sensitive to alkalinity (base) and heat Coenzyme form used in energy metabolism Deficiency: Beriberi (severe muscle weakness RDA – 1.1 mg/day for women – 1.2 mg/day for men – Most exceed RDA in diet Surplus is rapidly lost in urine; non-toxic Food Sources of Thiamin, fig. 8-14 Riboflavin Coenzyme forms participate in energyyielding metabolic pathways Deficiency – Cheilosis, inflammation of mouth and tongue, dermatitis, sensitivity to sun RDA – 1.1 mg/day for women – 1.3 mg/day for men – Average intake above RDA Non-toxic Food Sources of Riboflavin Milk/milk products Enriched grains/cereals Eggs Liver Spinach Oysters Brewer’s yeast Niacin Coenzyme forms used in energy metabolism Deficiency – Pellagra: rough/painful skin (epidemic US < 1930s) – Dementia, diarrhea, dermatitis, RDA – 14 mg/day for women – 16 mg/day for men Toxicity – Upper Level is 35 mg/day Food Sources of Niacin Enriched grains (breakfast cereals) Beef Chicken/turkey Fish Heat stable; little cooking loss 60 mg tryptophan (Amino acid) can be converted into 1 mg niacin Pantothenic Acid Part of Coenzyme-A – Essential for metabolism of carbohydrate, fat, and protein Deficiency rare – Usually in combination with other deficiencies Food Sources of Pantothenic Acid Meat Milk Mushrooms Liver Peanuts Adequate Intake = 5 mg/day Average intake meets AI Biotin Free and bound form Co-enzyme – Metabolism of carbohydrate and fat – Helps breakdown certain amino acids Deficiency–rare – Scaly, inflamed skin – Changes in tongue, lips – Decreased appetite, nausea, vomiting Food Sources of Biotin Cauliflower, egg yolk, liver, peanuts, cheese Intestinal synthesis of biotin contributes very little (10%) Avidin egg protein inhibits absorption – More than a dozen raw egg whites a day to cause this effect Biotin Needs Adequate adults No intake is 30 µg/day for Upper Level for biotin Relatively nontoxic Vitamin B-6 Coenzyme forms – Activate enzymes needed for metabolism of carbohydrate, fat, and protein – Synthesize nonessential amino acids via transamination – Synthesize neurotransmitters – Synthesize hemoglobin and WBC Food Sources of Vitamin B-6, fig. 8-22 RDA for Vitamin B-6 1.3 mg/day for adults 1.7 mg/day for men over 50 1.5 mg/day for women over 50 Daily Value set at 2 mg Average intake is more than RDA Athletes may need more Alcohol increases vitamin B-6 destruction Vitamin B-6 As a Medicine? 50-100 mg/day therapy – Questionable treatment of PMS – May treat pregnancy hypertension Carpal tunnel syndrome Morning sickness – (100 mg/day may help; see Ch. 13) Toxicity potential – > 200 mg/day can lead to irreversible nerve damage Upper Level set at 100 mg/day Folate Coenzyme – DNA synthesis – Homocysteine metabolism – Neurotransmitter formation Sensitive to: – Heat, oxidation, ultraviolet light Folate Deficiency Megaloblast cells Megaloblastic Anemia 10% N. Americans- genetic defect to process folate (req. 2X RDA), need genetic testing. . Neural tube defects Women need ample Folic acid: – Neural tube closes w/i 28 days of pregnancy spinal bifuda Megaloblast cells -Req. ample Folic acid Child bearing Women need ample Folic acid: Neural tube closes w/i 28 days of pregnancy spinal bifuda Food Sources of Folate Liver Fortified breakfast cereals Grains, legumes Foliage vegetables Orange juice RDA for Folate 400 µg/day for adults 600 µg/day for pregnant women Excess intake can mask vitamin B-12 deficiency Upper Level 1 mg (synthetic form) – Synthetic form 1.7 X more potent. . . – Folate in food has limited absorption (synthetic form) (Natural form) Vitamin B-12 Synthesized by bacteria and fungi Coenzyme – Role in folate metabolism – Maintenance of the myelin sheaths – RBC formation Deficiency (absorption problems) – Pernicious anemia (weakness, sore tongue, back pain) – Nerve degeneration and paralysis B-12 Absorption -aging Requires a protein from salivary gland Requires stomach acid (declines w/ age) Requires the intrinsic factor (declines w/ age) Absorbed in the last part of the small intestine About 50% of B-12 is absorbed Vegetarian/Vegan diets – low in Vit. B-12 – (need supplement or specified rich source) Therapy for Ineffective Absorption Many factors can disrupt this process Monthly injections of vitamin B-12 Vitamin B-12 nasal gel Megadoses of vitamin B-12 – Allow for passive diffusion Food Sources of Vitamin B-12 Synthesized by bacteria, fungi and algae (Stored primarily in the liver of animals) Animal products Organ meat Seafood Eggs yogurt Milk Corn flakes cereal (w/ soy milk) RDA for Vitamin B-12 2.4 µg/day for adults – Over age 50 recommended take synthetic form – Not bound to foods (no require low stomach acid) Average intake exceeds RDA B-12 stored in the liver (> 3 years before deficiency) Non-toxic Vitamin C Synthesized by most animals – Not by humans Decreased absorption with high intakes > 250mg Excess excreted – Diarrhea common Sensitive to – Cooking/heat (high temp) ~ use medium setting – Iron, copper, oxygen Functions of Vitamin C Synthesis of collagen (connective tissue) – Stretch marks Iron absorption Immune functions – Prevents duration of common cold? – Interacts with w/ oxidized Vit. E ~ recycles? – Anti-cancer agent and cataracts Antioxidant? Req. for syn. Of hormones Challenge Question What has more Vitamin C/gram and is the best dietary choice for combating the common cold and why? 1 medium orange 1 medium red pepper Deficiency of Vitamin C Scurvy – Deficient for 20-40 days – Fatigue, pinpoint hemorrhages – Bleeding gums – Weakness – Fractures – Associated with poverty Food Sources of Vitamin C Citrus fruits Potatoes Green pepper Cauliflower Broccoli Strawberries Romaine lettuce Spinach RDA for Vitamin C 90 mg/day for adult males 75 mg/day for adult females (enhances Fe absorptn.) Daily Value is 60 mg +35 mg/day for smokers Average intake 70-100 mg/day Upper Level is 2 g/day (inflammation diarrhea) Better to take low doses (250 mg) more frequent vs MegaDOSE 1 Gram (1000 mg) / day Choline Essential nutrient, though not a vitamin All tissues contain choline Precursor for acetylcholine (neurotransmitter) Precursor for phospholipids Food Sources of Choline Widely distributed in foods – Fruits/vegetables Milk Liver Eggs Peanuts Lecithin added to food Deficiency rare Needs for Choline Adequate Intake is 550 mg/day for males Adequate Intake is 425 mg/day for females Average intake is ~700-1000 mg/day High doses – Associated with fishy body odor, vomiting, salivation, sweating, hypotension, GI effects Upper Level is 3.5 grams/day Vitamin-like Compounds Choline Carnitine Inositol Taurine Lipoic acid Synthesized in the body at the expense of amino acids and other nutrients Vitamins-SUMMARY Functions in the Body With a balanced diet – no need for supplements? Dietary Supplements $21 Billion Dietary Supplements –Classified as Vitamins Minerals Fe2+ Herbs Amino Acids A dietary substance to supplement the diet Try a case study? Vitamins, Supplements SUMMARY If going to experiment . . . Make sure < (upper limit) of toxic level Min. 6 weeks for evaluation. . . ANY SUPPLEMENT QUESTIONS? See below Check any of the following 6 websites for validity – 1. www.acsh.org – 2. www.quackwatch.com – 3. www.ncahf.org – 4. http://dietary-supplements.info.nih.gov – 5. www.eatright.org – 6. www.usp.org/USPVerified/dietarySupplements/ **7. “web of science”- (use UCSC Lib login, http://oca.ucsc.edu/login (22200-0230485-15)