Chapter 11 Fat Soluble Vitamins: ADEK

1. Chapter 11 Fat Soluble Vitamins: ADEK

2. Chapter 11 - FSV Characteristics of fat-soluble vitamins • Do not dissolve in water, but dissolve in fat or organic solvents. • Dietary fat soluble vitamins need bile for absorption. • The fat-soluble vitamins include vitamins A, D,E and K • Found in the fats and oils of foods. • Stored in the liver and fat tissue until needed • not readily excreted from the body. • Risk of toxicity.

3. Storage of vitamins in the body • Vitamins A, D and E: • These three fat-soluble vitamins can accumulate in the liver and fat tissue of the body and are not readily excreted. Long-term intakes more than the RDA can be toxic, particularly vitamins A and D. • Vitamin K: • The other fat-soluble vitamin, vitamin K, is readily excreted from the body.

4. Absorption & transport • The fat-soluble vitamins, like lipids are absorbed with dietary fat. • Bile aids in the absorption of fat-soluble vitamins. • The GI must function adequately for efficient uptake of fat-soluble vitamins. • Under normal conditions, healthy individuals will absorb 40-90% of fat-soluble vitamins.

5. Absorption & Transport Fat malabsorption interfere with the absorption of FSV. • Unabsorbed fat is excreted as feces. • The following conditions adversely affect the uptake of fat-soluble vitamins: • Cystic fibrosis • Crohn’s disease • Celiac disease • Certain medications

6. Vitamin A Family of compounds called Retinoids: • Retinol – supports reproductive functions • Found in animal foods and nutrient supplements. • Can converted to retinoic acid and retinal in the body. • Retinal – Aid in vision • Retinoic acid – regulates growth • ~90% of retinoids are absorbed • These are preformed Vitamin A – form that the body readily uses. Found only in animal sources

7. Provitamin A = carotenoids • Found in plant sources • Not biologically available until they are changed into one of the retinoids in the body • There are over 600 different carotenoids only 3 can be converted to vitamin A • Beta carotene (most common form) • Alpha carotene • Beta- cryptoxanthin • Accounts for 25 – 35 percent of dietary vitamin A consumed in the US

8. Functions of Vit A • Essential for healthy eyes • Promotes cell differentiation • Determines what cell becomes in your body • Supports reproductive system, development of limbs, heart eyes and ears • Promotes bone and teeth growth • Play a role in immunity and preventing infections by creating white blood cells • Carotenoids, which act as antioxidants, decrease the damaging effects of free radicals.

9. Sources of Vitamin A Sources • Preformed Vit A • Organ meats (liver), milk, cereals, cheese and eggs are the most popular sources of • Provitamin A (carotenoids) • Fruits: peaches, apricots, cantaloupes, mangoes, papaya • Vegetables: tomatoes, carrots, winter squash, sweet potatoes, broccoli, romaine lettuce, collard greens and spinach. • Adding as little as 1 tablespoon of vegetable oil to your diet can increase absorption of carotenoids by as much as 25%

10. Vitamin A RDA – can be measured in micrograms of retinoic activity equivalents (RAE) or in international units (IU). 1 RAE = 3.3 IU • 900 microgram for men • 700 microgram for women • Upper limit 3,000 microgram/day Deficiency • Night blindness – difficulty seeing at dusk, can’t adjust from day light to dark • Vitamin A deficiency is the main cause of non-accidental blindness (Xerophthalmia) • Many die after blindness as a result of infection. • The eye becomes prone to infections when the conjunctiva is damaged. • Infections can spread systemically throughout the body.

12. Toxicity • Hypervitaminosis A - is a condition that results from excessive intake of vitamin A from supplements • Cause defective physical development during early development of the fetus resulting in birth defects • Even 3X RDA vitamin A is considered risky during pregnancy. • Accutane is associated with congenital malformations result involving the head and brain. • FDA has recommended that women of childbearing years limit their vitamin A intake to 100% RDA

13. Toxicity • High consumption of vitamin A has been linked to osteoporosis and increased risk of fractures • Provitamin A carotenoids in foods are not toxic • Extra carotenoids are stored in the liver and in the fat under the skin, causing carotenodermia

14. Fig. 11-7, p. 375

15. Vitamin D/calceferol • Also called the “sunshine vitamin” because it is made with the help of ultraviolet (UV) rays from sunlight • Vitamin D enters your body in an inactive form • The kidneys convert dietary vitamin D into the active form • Precursor = body’s cholesterol

16. Vitamin D/ calceferol • Functions of Vit D • Helps bone health by regulating calcium and phosphorus concentration in the blood • When blood concentration of calcium is low, vitamin D and parathyroid hormone signals the kidney to decrease excretion of calcium and phosphorous • Sources of vit D • Fortified milk, cereals, yogurt, fatty fish

17. Vitamin D Adequate Intake: • 5 micrograms/day for 19-50 yr • 10 micrograms/day for 51-70 yr • 15 micrograms/day for >70 yr • Upper level: 50 micrograms/day

18. Vitamin D Deficiency • Rickets in children (soft bones) • poor bone mineralization • Bowed legs • Unable to hold up their own weight when standing up • Recently researchers have found a rise in rickets among children, • linked to increase consumption of soft drinks • Limited outdoor activities • Fear of skin cancer • Air pollution reduces ultraviolet rays of the sun by as much as 60%

20. Vitamin D Osteomalacia - adult form of rickets • Occurs in women with decreased calcium and phosphorus intake • Causes bone weakness and pain • Can lead to osteoporosis

21. Vitamin D Toxicity Hypervitaminosis D – associated with over-consumption of supplements • Increased calcium withdrawal in bones and intestines • Increased calcium and phosphorous concentrations in the blood (hypercalcemia) • Increase calcium deposits in kidneys, lungs, blood vessels and heart

22. Vitamin E • Vitamin E is an effective antioxidant • Prevent oxidation of lipids, vit A and LDL to prevent build-up in the arteries • Neutralize free radicals before they damage cell membranes • Prevents blood clotting in the blood by acting as anticoagulant • There are 8 different forms, only one is active in the body (alpha- tocopherol) • The synthetic is only half as active as the natural

23. Vitamin E Sources • Polyunsaturated plant oils (vegetable oils) • Nuts and seeds • Leafy green vegetables • Fortified cereals RDA: Adults need 15 milligrams/day Upper limit is 1,000 milligrams

24. Vitamin E Deficiency • Erythrocyte hemolysis in premature infants (red blood cell destruction causing anemia) Toxicity from synthetic form or fortified foods • increase risk of hemorrhage • A deficiency of vitamin K can increase the anticoagulant effect

25. Vitamin K There are two forms of vitamin K: • Menaquinone – synthesized by the intestinal tract • Phylloquinone – found in green plants Functions • Essential for blood clotting • Vitamin K plays a role synthesizing clotting factors • Without vit k a simple cut on the finger would cause uncontrollable bleeding • Synthesis of bone protein (osteocalcin) that regulates blood calcium.

26. Vitamin K • Inadequate amount of vitamin K may contribute to osteoporosis, associated with increased risk of hip fractures Sources • Intestinal bacteria can make vitamin K but not enough to meet all of the body’s needs • Leafy green vegetables • Cabbage family vegetables • Vegetable oils and margarine

27. Vitamin K Deficiency • Newborn infants receive a single dose of vitamin K at birth because of a sterile intestinal tract to prevent hemorrhagic disease • Rare in healthy individuals Toxicity • No known adverse effect from consuming too much vitamin K from food or supplement • Interferes with anticlotting medication (coumadin)

28. Recommendation for Vitamin K Adequate Intake (based on amount that is consumed on average) Infants: 2 – 2.5 microgram Children: 30 – 55 microgram Men: 60 – 120 microgram Women: 60 – 90 microgram

29. Homework/extra credit 5 points Complete the vitamin/mineral evaluation form posted on the course website