Chapter 8 Vitamins

1. Chapter 8Vitamins

2. 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

3. 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,…)

4. 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

5. 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

6. 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

7. 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

8. Preservation Tips

9. Fat-Soluble Vitamins Overview • Dissolve in organic solvents • Not readily excreted • Can cause toxicity • Absorbed along with fat • Fat malabsorption (Xenical/Olestra) • May cause deficiency • Cystic fibrosis (Vit. deficiency) • Transported with fat • In lipoproteins Olestra Xenical

10. Confirming your knowledgeWhat are the fat Soluble vitamins, why (i.e. non polar)? 1 2 3 4

11. 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

12. 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)

13. 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

14. Food Sources of Vitamin A: see: 8-2

15. Recommended Amounts for Vitamin A • 900 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

16. 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

17. 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

18. Activation of Vitamin D

19. 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

20. 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 Role in Bone Formation

21. 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.

22. Food Sources of Vitamin D • Fatty fish (salmon, herring) • Fortified milk (N. fat, Low fat or Whole) • Some fortified cereal

23. 5 g/day (200 IU/day) for adults under age 51 10-15 g/day (400 - 600 IU/day) for older adults Supplement if a breastfed infant (See physician for details) Adequate Intake (AI) for Vitamin D

24. 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

25. Vitamin E • Fat-soluble antioxidant • αβδ gamma tocopherol forms • Resides mostly on cell membranes

26. 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

27. Food Sources of Vitamin E

28. 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

29. Vitamin E • SHOW Vit E video

30. 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

31. 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)

32. 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

33. 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 milledloose vitamins . .) • Must be added back (enriched) to products (cereals) • Why experts recommend whole grains/brown rice vs Refined grain products

34. Confirming your KnowledgeOverview of Water-Soluble Vitamins • What are the water soluble vitamins and why (i.e. polar) ? (4) (3) (2) (1) (5) (6) (9) (7) (8)

35. Overview of Water-Soluble Vitamins Participate in energy metabolism

36. 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

37. Food Sources of Thiamin, fig. 8-14

38. Riboflavin • Coenzyme forms participate in energy-yielding 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

39. Food Sources of Riboflavin • Milk/milk products • Enriched grains/cereals • Eggs • Liver • Spinach • Oysters • Brewer’s yeast

40. 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

41. 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

42. Pantothenic Acid • Part of Coenzyme-A • Essential for metabolism of carbohydrate, fat, and protein • Deficiency rare • Usually in combination with other deficiencies

43. Food Sources of Pantothenic Acid • Meat • Milk • Mushrooms • Liver • Peanuts • Adequate Intake = 5 mg/day • Average intake meets AI

44. 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

45. 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

46. Biotin Needs • Adequate intake is 30 µg/day for adults • No Upper Level for biotin • Relatively nontoxic

47. 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

48. Food Sources of Vitamin B-6, fig. 8-22

49. 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

50. 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