Understanding Fat-Soluble Vitamins: A Comprehensive Overview

1. Fat soluble vitamins FACS 113 Susan Algert

2. Fat Soluble Vitamins • Dissolve in organic solvents • Not readily excreted and can cause toxicity • Fat malabsorption can cause deficiency • Transported like fat in chylomicrons, VLDL, LDL and other protein carriers

3. Vitamins • Essential organic substances • Yield no energy, but facilitate energy yielding reactions • Will produce deficiency signs and symptoms if absent from the diet • Fat soluble and water soluble

4. Forms of Vitamin A • Preformed are retinyl esters retinoids (retinal retinol, retinoic acid) found in animal products

5. Provitamin A • Carotenoids (beta carotene, alpha carotene, lutein, lycopene, zeaxanthin) • Must be converted to retinoid form • Found in plant products • Most biologically active provitamin is beta carotene

6. Transport and Storage • Liver stores 90% of vitamin A in the body • Reserve is adequate for several months • Transported from the liver as retinol via retinol binding protein to target tissue • Caroteinoids can be transported via CM and VLDL • Target cells contain intracellular retinol binding proteins

7. Vitamin A roles in the body • Promotes vision (retinol) • Supports protein synthesis and cell differentiation (retinoic acid) • Night and color vision (retinal)

8. Cartenoids roles in the body • Antioxidant • Vision • Cancer • Heart disease

9. The visual cycle • Cones in the retina Are responsible for vision under bright light Translate objects to color vision • Rods in the retina responsible for vision in dim light translate objects in black and white vision

10. Cell health and maintenance • Retinoic acid influences how the epithelial cells differentiate and mature • Without vitamin A cells will not differentiate • Leads to follicular hyperkeratosis

11. Growth and development • Retinoic acid is necessary for cellular differentiation • Retinoic acid triggers specific nuclear receptors in the DNA for differentiation • Important

12. Preformed Liver, fish oils, fortified milk, eggs half of vitamin A intake Proformed Dark leafy green, yellow, orange veggies; also half of vitamin A intake Food Sources

13. Retinol Activity Equivalents • 1 RAE = • 1 ug retinol • 12 ug beta corotene • 24 ug of other vitamin A • Precursor carotenoids

14. IU of vitamin A • 0.3 ug retinol • 3.6 ug beta carotene • 7.2 ug of other vitamin A precursors

15. RDA for vitamin A • 1000 RE for men • 800 RE for women • Average intake meets RDA • No separate RDA for caroteniods

16. Vitamin A deficiency • Less than 500 ugms per day • Growth failure • Infectious disease (diarrhea, measels) • Night blindness • Xeropthalmia • keratinization

17. Toxicity • Results from long term supplement use (3-10 X RDA or 15,000 ug RE) • Large intake of vitamin A over long period of time • bone./muscle pain, loss of appetite, skin disorders, headache, dry skin, hair loss • Discontinue supplementation, possible permanent damage • Hypercarotenemia from caroteinoids

18. Vitamin D • Prohormone • Derived from cholesterol • Synthesis from sun exposure • Insufficient sun exposure makes this an essential nutrient • Activated by enzymes in the liver • Deficiency can cause disease; rickets or osteomalacia

19. Functions of Vitamin D • Calcitrol influences differentiation of cells • Increased protein synthesis • Stimulates calcium binding protein in the intestine • Enhances calcium absorption in the intestine

20. Vitamin D role in bone formation • Decreases calcium excretion in the kidney • Causes Ca and Phos to deposit in the bones • Strengthens bones • Mobilizes calcium from bones depending on blood calcium level

21. Food sources • Fatty fish such as salmon and herring • Fortified milk • Other fortified foods

22. Adequate intake of vitamin D • 5 ug/day (200 IU) for adults • 10-15 ug/day (400-500 IU) for over age 51 • Casual sun exposure usually produces enough vitamin D • Infants are born with sufficient D to last 9 months

23. Toxicity of vitamin D • Regular intake of 5-10 x the AI can be toxic • Results from excessive supplementation and not from sun exposure or milk consumption • Overabsorption of calcium (hypercalcemia) and increased calcium excretion

24. Vitamin E • Tocopherols and tocotrienols • Tansported via chylomicrons • Found concentrated in areas where fat is found

25. Antioxidant or redux agent • Vitamin E is able to donate electron to oxidizing agent • Protects the cells from attack by free radicals production is normal result of cell metabolism destructive to cell membrane

26. Functions of vitamin E • Protects the double bonds in fat • Role in iron metabolism • Maintenance of nervous tissue and immune function

27. Food sources of vitamin E • Plant oils and margarines • Wheat germ • Asparagus • Dark green leafy vegetables • Nuts and seeds

28. RDA for vitamin E • 8 mg/day for women • 10 mg/day for men • Average intake meets RDA • 1 mg vitamin E = 1.5 IU (from food source) = 1.0 IU (from synthetic source)

29. Deficiency • Red blood cell fragility • Neurological disorders affecting the spinal cord • Anti aging vitamin?

30. Toxicity of vitamin E • Supplements up to 800 IU is probably harmless • TUL is 1 gm/day • Inhibits vitamin K metabolism and anticoagulants

31. Vitamin K • Phylloquinones and menaquinones are active forms • Role in the coagulation process • Calcium binding potential • Formation of osteocalcin

32. ood sources of vitamin K • Liver • Green leafy vegetables • Broccoli • Peas • Green beans • Resistant to cooking losses • Limited vitamin K stores in the body

33. Drug Interactions • Anticoagluant Lessen blood clotting process Need to monitor vitamin K intake • Antibiotics destroy intestinal bacteria inhibits vitamin K synthesis and absorption potential for excessive bleeding

34. RDA for vitamin K • 60-65 mg/day for women • 65-80 mg/day for men • RDA is met by most people • Excess vitamin A and E interfere with K • Newborns are injected with vitamin K • Toxicity unlikely; readily excreted • Deficiency leads to bleeding/ hemmorhage