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Water-Soluble Vitamins

Water-Soluble Vitamins

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Water-Soluble Vitamins

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  1. Water-Soluble Vitamins • Water soluble • Readily excreted – expensive urine • Can be lost from food by cooking/storage • Typically work as part of enzymes in metabolism • Relatively high absorption rate • Severe deficiencies rare • Vitamins – Niacin, Thiamine, Folic Acid, Riboflavin, B12, and C.

  2. Enrichment Act of 1941 and 1998 • Milling of rice, wheat, oats, etc… • significantly reduces nutritional quality • Whole grains contain original nutrients • Enrich with • thiamin, riboflavin, niacin, folate, iron • Enriched grains still • deficient in B-6, magnesium and zinc

  3. Thiamin • Destroyed by alkaline and heat • Coenzyme: Thiamin pyrophosphate (TPP) • Absorbed in the jejunum by a carrier-mediated system • Transported by RBC in the blood • Deficiency • Beriberi • Weakness, nerve degeneration, irritability, poor arm/leg coordination, loss of nerve transmission • Edema, enlarge heart, heart failure

  4. Food Sources of Thiamin • Wide variety of food • White bread, pork, hot dogs, luncheon meat, cold cereal • Enriched grains/ whole grains • Thiaminase found in raw fish • 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

  5. Riboflavin • Coenzymes: • Flavin mononucleotide (FMN) • Flavin adenine dinucleotide (FAD) • Oxidation-reduction reactions • Electron transport chain • Citric Acid Cycle • Catabolism of fatty acids

  6. Absorption, Transport, & Metabolism of Riboflavin • HCL in the stomach release riboflavin from its bound forms • Absorption • Active or facilitated transport during low to moderate intake • Passive absorption during high intake • Increase with intake • Transported by a protein carrier in the blood

  7. Functions of Riboflavin • Accepts electrons • Electron Transport Chain • FAD FADH2 • Succinate Fumarate • Citric Acid Cycle • Participates in beta oxidation • FMN shuttles hydrogen ions and electrons to into the electron transport chain • Metabolism of oxidized glutathione

  8. Deficiency of Riboflavin • Ariboflavinosis • Glossitis, cheilosis, seborrheic dermatitis, stomatitis, eye disorder, throat disorder, nervous system disorder • Occurs within 2 months • Usually in combination with other deficiencies

  9. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glossitis (Fig. 10-4)

  10. Who is at Risk For Deficiency? • Rare • Low milk/dairy intake • Alcoholics • Long term phenobarbital use

  11. Food Sources of Riboflavin • Milk/products • Enriched grains • Liver • Oyster • Brewer’s yeast • Sensitive to uv radiation (sunlight) • Stored in paper, opaque plastic containers

  12. RDA for Riboflavin • 1.1 mg/day for women • 1.3 mg/day for men • Average intake is above RDA • Toxicity not documented

  13. Niacin • Nicotinic acid (niacin) & nicotinamide (niacinamide) • Coenzyme • Nicotinamide adenine dinucleotide (NAD) • Nicotinamide adenine dinucleotide phosphate (NADP) • Oxidation-reduction reaction • Metabolic reactions

  14. Absorption, Transport and Storage of Niacin • Readily absorbed from the stomach and small intestine • Absorption: active transport and passive diffusion • Transported from the liver to all of the tissues where it is converted to the coenzymes

  15. Deficiency of Niacin • Pellagra • 3 Ds • Occurs in 50-60 days • Decrease appetite & weight • Prevented with an adequate protein diet • Enrichment Act of 1941 • Only dietary deficiency disease to reach epidemic proportions in the U.S. • Who is at risk? • (Untreated) corn as main staple, poor diet, Hartnup disease, alcoholics

  16. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dermatitis of Pellegra (Fig. 10-5)

  17. Mushroom Enriched grains Beef, chicken, turkey, fish Heat stable; little cooking loss 60mg tryptophan can be converted into 1 mg niacin Food Sources of Niacin

  18. RDA for Niacin • 14 NE/day for women • 16 NE/day for men

  19. Niacin as a Medicine • 75-100 x RDA can lower LDL and TG and increase HDL • Slow/ reverse progression of atheroscelerosis with diet and exercise • Toxicity effects • Flushing of skin, itching, nausea, liver damage

  20. Biotin • Free and bound form • Biocytin (protein bound form) • Biotinidase in small intestine • Metabolism of CHO, fat, protein (C skeleton) • DNA synthesis

  21. Functions of Biotin • Assists in the addition of CO2 to substances • Carboxylation of acetyl-CoA to form malonyl-CoA for the elongation of a fatty acid chain • Addition of CO2 to pyruvate to yield oxaloacetate • Breaks down leucine • Allows 3 essential amino acids to be oxidized for energy

  22. Food Sources of Biotin • Cauliflower, yolk, liver, peanuts, cheese • Intestinal synthesis of biotin • Biotin content only available for a small number of foods • Unsure as to bioavailablity of synthesized biotin • We excrete more than we consume • Avidin inhibits absorption • > a dozen of raw eggs a day to cause this effect

  23. Biotin Needs • Adequate Intake is 30 ug/day for adults • This may overestimate the amount needed for adults • No Upper Limit for biotin

  24. Who is at Risk For Deficiency? • Rare • High intake of raw egg white diet • Alcoholics • Biotinidase deficiency • Anticonvulsant drug use • Signs & symptoms: skin rash, hair loss, convulsion, neurological disorders, impaired growth in children

  25. Vitamin B-6: Pyridoxal, Pyridoxine, Pyridoxamine • Main coenzyme form: pyridoxal phosphate (PLP) • Activate enzymes needed for metabolism of CHO, fat , protein • Transamination • Synthesis of hemoglobin and oxygen binding and white blood cells • Synthesis of neurotransmitters

  26. Deficiency of Vitamin B-6 • Microcytic hypochromic anemia • Seborrheic dermatitis • Convulsion, depression, confusion • Reduce immune response • Peripheral nerve damage • Who is at risk? • Elderly • Alcoholics • Alcohol decreases absorption • Destroy the coenzyme form

  27. Food Sources of Vitamin B-6 • Meat, fish, poultry • Whole grains (not enriched back) • Banana • Spinach • Avocado • Potato • Heat and alkaline sensitive

  28. 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 the RDA

  29. Factors That Affect B-6 Requirement • L-DOPA-medication used to treat Parkinson’s disease and • Isoniazid-antituberculosis medication • Reduce blood concentration of PLP • Need extra vitamin B-6 • Preeclampsia • Reduce blood concentration of PLP • Will supplementation will reduce preeclampsia?

  30. B-6 As A Medicine? • PMS • B-6 to increase the level of serotonin • Improve depression • Not a reliable treatment • Carpal tunnel syndrome • Toxicity potential • Can lead to irreversible nerve damage with > 200 mg/day

  31. Folate (Folic acid, Folacin) • Consists of pteridine group, para-aminobenzoic acid (PABA), and glutamic acid • Coenzyme form: tetrahydorfolic acid (THFA)

  32. Functions of Folate • DNA synthesis • Transfer of single carbon units • Synthesis of adenine and guanine • Anticancer drug methotrexate • Homocysteine metabolism • Neurotransmitter formation

  33. Deficiency of Folate • Similar signs and symptoms of vitamin B-12 deficiency • Pregnant women • Alcoholics • Interferes with the enterohepatic circulation of bile/folate

  34. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neural Tube Defects • Spina bifida • Anencephaly • Importance of folate before and during pregnancy (Fig. 10-8)

  35. Food Sources of Folate • Liver • Fortified breakfast cereals • Grains, legumes • Foliage vegetables • Susceptible to heat, oxidation, ultraviolet light

  36. RDA for Folate • 400 ug/day for adults • Daily Value is set at 400 ug

  37. Vitamin B-12 • Cyanocobalamin. methlcobalamin, • 5-deoxyadenosylcobalamin • Contains cobalt • Folate metabolism • Maintenance of the myelin sheaths • Rearrange 3-carbon chain fatty acids so can enter the Citric Acid Cycle

  38. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Absorption of Vitamin B-12 (Fig. 10-10)

  39. Functions of Vitamin B-12 • Helps convert methylmalonyl CoA to succinyl CoA (citric acid cycle) • RBC formation • Nerve functions • Maintains myelin sheath • Megalobalstic anemia

  40. Deficiency of Vitamin B-12 • Pernicious anemia • Never degeneration, weakness • Tingling/numbness in the extremities (parasthesia) • Paralysis and death • Looks like folate deficiency • Usually due to decreased absorption ability • Achlorhydria especially in elderly • Injection of B-12 needed • Takes ~20 years on a deficient diet to see nerve destruction

  41. Who is at Risk For Deficiency? • Vegans • Breastfed infants of vegan moms • Elderly • Individuals with AIDS or HIV

  42. Synthesized by bacteria, fungi and algae (Stored primarily in the liver) Animal products Organ meat Seafood Eggs Hot dogs Milk Food Sources of Vitamin B-12

  43. RDA for Vitamin B-12 • 2.4 ug/ day for adults and elderly adults • Average intake exceeds RDA • B-12 stored in the liver • Non-toxic

  44. Vitamin C • Ascorbic acid (reduced form), dehydroascorbic acid (oxidized form) • Synthesized by most animals (not by human) • Absorbed by a specific energy dependant transport system • Passive transport if intake is high • Decrease absorption with high intakes • Excess excreted

  45. Functions of Vitamin C • Reducing agent (antioxidant) • Iron absorption • Synthesis of carnitine, tryptophan to serotonin, thyroxine, cortiscosteroids, aldosterone, cholesterol to bile acids • Immune functions • Cancer prevention? • Collagen synthesis

  46. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Collagen Synthesis (Fig. 10-12)

  47. Antioxidant • Can donate and accept hydrogen atoms readily • Water-soluble intracellular and extracellular antioxidant • Must be constantly enzymatically regenerated • Needs are higher for smokers

  48. Scurvy Deficient for 20-40 days Fatigue, pinpoint hemorrhages Bleeding gums and joints. Hemorrhages Associated with poverty Rebound scurvy immediate halt to excess vitamin C supplements Who is at risk? Infants, elderly men Alcoholics, smokers Deficiency of Vitamin C

  49. Citrus fruits Potatoes Green peppers Cauliflower Broccoli Strawberries Romaine lettuce Spinach Easily lost through cooking Sensitive to heat Sensitive to iron, copper, oxygen Food Sources of Vitamin C