Fat Soluble Vitamins E, K

Fat Soluble Vitamins E, K - 1 Fat Soluble Vitamins 3...

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Unformatted text preview: 1 Fat Soluble Vitamins 3 Vitamins E and K NDFS 435 Objectives • Discuss vitamin E and K forms, digestion, transport and storage • Learn vitamin E’s antioxidant mechanism • Learn the vitamin K cycle • Explore some clinical applications for E and K 2 3 Vitamin E History 1 • 1922 Evans and Bishop, UC Berkeley – Rat diet made with rancid lard • Female rats conceived, but could not complete the pregnancy. – Recognized that something in the lard was necessary for pregnancy. • Named vitamin E • Chemical name given by a Greek professor – Tocopher = to bring forth in childbirth –-ol = oil – Tocopherol 4 Vitamin E History 2 • 1930’s – 1960’s – Vitamin E deficiency effects determined in many animal species • Many different effects – Reasons unclear at that time – Unreliable literature would compile the animal results and imply that vitamin E deficiency in humans had the same results 5 Vitamin E History 3 • 1960’s – One group said that vitamin E would prevent heart disease – Several controlled studies followed • No effect was found on lowering serum cholesterol – Papers stated that vitamin E had no effect on heart disease – Lowering serum cholesterol was the only risk factor identified at this time • Late 1960’s – Antioxidant properties of vitamin E postulated • New era began 6 Methyl Positions Tocol Tocotrienol 5, 7, 8 α- (alpha) α 5, 8 β- (beta) β 7, 8 γ- (gamma) γ 8 δ- (delta) δ O CH 3 R 1 or R 2 R 3 R 2 HO R 1 1 2 3 4 5 6 7 8 T o c o l s R 1 = CH 2 (CH 2-CH 2-CH-CH 2 ) 3 H T o c o t r i e n o l s CH 3 R 2 = CH 2 (CH 2-CH=C-CH 2 ) 3 H CH 3 7 Chiral groups Nature Synthesis Synthesis of alpha- tocopherol results in a racemic mixture of all 8 isomers. Nature only makes the RRR isomer. Chiral groups determine the isomers Only alpha-tocopherol has been shown to reverse an induced vitamin E deficiency in humans. 8 Recommendations • 1989 RDA: RRR-α-tocopherol equivalents – Men: 10 mg – Women: 8 mg – Included the 8 naturally occurring tocopherols • 2000 RDA: α-tocopherol ( not equivalents) – Men and Women: 15 mg – This RDA uses the following isomers of α-tocopherol • RRR, RSR, RRS, RSS (note: all are 2R forms) – UL adults 1000 mg • Includes both R and S forms • For supplements only • Nutritional versus pharmacological levels 9 Food Sources of Alpha- tocopherol (2R forms) 1. Alpha-tocopherol has the highest biological activity. Vegetables and nuts are good sources. 2. Plant oils usually are high in α- tocopherol and its content is usually proportional to the PUFA in the oil. 3. Corn and soybean oil are exceptions. They are high in gamma-tocopherols. Cottonseed oil is half/half for the alpha and gamma forms....
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This note was uploaded on 03/26/2012 for the course NDFS 435 taught by Professor Toryparker during the Winter '11 term at BYU.

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Fat Soluble Vitamins E, K - 1 Fat Soluble Vitamins 3...

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