Supplements for athletes Vitamins – introduction Food safety

1. Recap of last lecture • Supplements for athletes • Vitamins – introduction • Food safety

2. #16 Outline for today • Fat-soluble vitamins • overview • Next time: Water-soluble vitamins

3. Answers to some of your questions • Cooking with a microwave • Antibiotics (effects, in foods) • Irradiation of foods

4. Food preservation • Classical - Salt, sugar, smoke, drying, fermentation • Decrease water content except fermentation • Modern - Pasteurization, freezing, refrigeration, canning, preservatives, “sterilization” • Irradiation • Food is not radioactive • Kills bacteria • Approved – raw red meat, eggs, seeds (hot dogs?) • Effective on many others including fruits and vegies

5. Vitamins • There are 4 fat soluble vitamins • 9 water soluble vitamins for a total of 13. • Your text also lists choline with the water soluble vitamins although it is not considered a vitamin since there is no known deficiency disease

6. Fat-Soluble Vitamins Overview • Not readily excreted; can cause toxicity • Absorbed along with fat • Concern for people with fat malabsorption or use of certain medication (e.g. orlistat or Xenical) • Transported like fat in chylomicrons, VLDL, LDL • Mostly metabolized in liver *

7. Pro-Vitamins • Precursors of vitamins • Are converted into the active vitamin form • E. g. beta-carotene converted into vitamin A

8. Vitamin A • Chemical names: 3 forms: retinol, retinal, retinoic acid • Most common cause of non-accidental blindness, worldwide • Active forms • Retinoids (retinal, retinol, retinoic acid) • Found in animal products • Pro-forms • Carotenoids (beta-carotene, alpha carotene,lutien, lycopene, zeaxanthin) • Must be converted to retinoid form • Found in plant products

9. Terminal Ends of Retinoids Retinyl esters beta-carotene H H O C OH C O C O H H Retinol Retinal Retinoic Acid Retinyl esters beta-carotene H H O C OH C O C O H H Retinol Retinal Retinoic Acid

10. Functions of Vitamin A • Retinol is needed for reproduction • Retinoic acid supports growth and cell maturation (also anti-acne medication) • Retinal is needed for night and color vision • Major use is in cell differentiation • Also act as antioxidants

11. The Visual Cycle • Cones in the retina • Responsible for vision under bright lights • Translate objects to color • Rods in the retina • Responsible for vision in dim light • Translate objects to black and white

12. Absorption of Vitamin A • Requires bile, digestive enzymes • Dependent on the fat in the diet • 90% of retinoids can be absorbed • Only ~30% of carotenoids are absorbed • Intestinal cells convert carotenoids to retinoids

13. Transport and Storage of Vitamin A • Liver stores 90% of vitamin A in the body • Reserve is adequate for several months • Transported via chylomicrons to the liver • Transported from the liver as retinol via retinol-binding protein to target tissue • Carotenoids can be transported via VLDLs

14. Vitamin A and resistance to disease • Deficiency leads to epithelial (skin) cell problems – allowing cracks and bacterial invasion • Deficiency leads to poor mucus formation • Deficiency reduces activity of some immune-system cells • High-dose therapy of vitamin A increases immune response

15. Cancer and Carotenoids • Role in cell development and immune-system • Role as an antioxidant • Lower risk of breast cancer with vitamin A supplements • Megadoses not advised • Mixed results in cancer/vitamin A studies • Foods rich in vitamin A and other phytochemicals are advised

16. Sources of Vitamin A • Preformed • Liver, fish oils, fortified milk, eggs • Typically contributes half of vitamin A intake • Pro-forms • Dark leafy green , yellow-orange vegetables/fruits • Typically contributes half of vitamin A intake

17. Deficiency of Vitamin A • Night blindness • Decreased mucus production • Leading to bacterial invasion in the eye • Conjunctival xerosis • Bitot’s spots • xerophthalmia • Irreversible blindness

18. Toxicity of Vitamin A Hypervitaminosis A • Result of long-term supplement use (3-10x >RDA) Acute • Ingestion of LARGE dose(s) of vitamin A (within a short period) • Result in intestinal upset, headache, blurred vision, muscular incoordination • Symptoms disappear when supplements are stopped • Can be lethal

19. Toxicity of Vitamin A Chronic Large intake of vitamin A over a long period Bone/muscle pain, loss of appetite, skin disorders, headache, dry skin, hair loss, increased liver size, vomiting Discontinue supplement is recommended Possible permanent damage

20. Toxicity of Vitamin A Teratogenic • Tends to produce physical defect on developing fetus as a result of excess vitamin A intake • Spontaneous abortion, birth defects • May occur with as little as 3 x RDA of preformed vitamin A Upper Level for Vitamin A • 3000ug for adults Fatal dose -12 g of vitamin A can be fatal

21. Effects of Vitamin A

22. Vitamin D • Prohormone (conversion of vitamin D-3 into the hormone 1,25-dihydroxy-calciferol = calcitriol) • Derived from cholesterol • Synthesis from sun exposure • Insufficient sun exposure makes this a vitamin • Activated by enzymes in liver and kidneys • Deficiency can cause diseases

23. Absorption of Vitamin D • ~80% of vitamin D consumed is incorporated into micelles • Absorbed in the small intestine and transported via chylomicrons • Transported through the lymphatic system

24. Metabolism and Storage of Vitamin D • Activation by the liver and the kidneys • Stored in fat tissue • Activate vitamin D when calcium is inadequate • Excretion of vitamin D mainly via bile

25. Vitamin D Synthesis

26. Regulate blood calcium level Functions of Vitamin D

27. Calcitriol is able to influence differentiation and function of some cells Linked to reduction of breast, colon, and prostate cancer development Vitamin D and Cell Differentiation

28. Calcitriol creates a supersaturated Ca + Phos solution Causes Ca + Phos to deposit in the bones Strengthen bones Rickets is the result of low vitamin D Osteomalacia (soft bone) is rickets in the adult Role in Bone Formation

29. Food Sources of Vitamin D • Fatty fish (salmon, herring) • Fortified milk • Some fortified cereal

30. Toxicity Warning • Vitamin D can be very toxic • Regular intake of 5-10x the AI can be toxic • Results from excess supplementation (not from sun exposure or milk consumption) • Sign and symptoms: over absorption of calcium (hypercalcemia), increase calcium excretion • Calcium deposits in kidneys, heart, and blood vessels, narrowing of pulmonary arteries and aorta, facial changes, mental retardation

31. Vitamin E • Tocopherols and tocotrienols • Amount absorbed is dependent on fat intake • Dependent on bile and pancreatic enzyme for absorption • Incorporated into chylomicrons to the liver then incorporated into lipoproteins • Stored in adipose tissue, liver, and muscle • Found in cell membranes

32. Antioxidant • Protects the cell from attack by free radicals and ROS = reactive oxygen species • Peroxyl-radical from fat breakdown • Protects PUFAs within the cell membrane and plasma lipoproteins • Prevents the alteration of cell’s DNA and risk for cancer development

33. Free Radicals • Production is normal result of cell metabolism • Destructive to cells; sets off a chain reaction • Lipid peroxidation • More vitamin E is found in the lungs • Smoking causes significant oxidative damage

34. Protection From Oxidative Damage • Glutathione peroxidase • A selenium containing enzyme • Helps breakdown peroxidized fatty acids (that tends to form free radical) • Lessens the burden of vitamin E • Superoxide dismutase and catalase • React with peroxide and superoxide (free radicals) • Reduce free radical activity

35. The More The Better? • Vitamin E is only one of many antioxidant • It is likely that the combination of antioxidant is more effective • Diversify your antioxidant intake with a balanced and varied diet • Megadose of one antioxidant may interfere with the action of another • Supplement of vitamin E for CVD is questionable