Vitamin E natural compounds

Alpha-Tocopherol a.k.a. Vitamin E

Vitamin E Vitamin E is a famil of  tocopherols and corresponding tocotrienols izomers. They are formed from chroman ring and hydrofobic fytyl side chain. The highest biological activity has  -tokoferol.

Vitamin E as an antioxidant R  + TOH  RH + TO 

Vitamin E as antioxidant Stops free radical reactions (peroxyl radicals ROO , oxygen radicals HO , lipoperoxid radicals LOO  ). Chroman ring with OH group → uptake radicals.

Oxidative damage Free radicals Quenched radical Vitamin E Function

Absorption and Transport Dependent on ability to absorb fat Absorbed into lymphatic system Component of chylomicrons Alpha-tocopherol is major tocopherol in plasma Positive association between serum lipid and tocopherol levels Normal range is mg/dl

E-Facts Plays a role in immune function, DNA repair, other metabolic processes, and in protecting other antioxidants U.S. RDA : 15 mg (22.5 IU) per day Typical Western diet provides 14 mg (21 IU) of Vit E Upper allowable intake (prior to Meta-Analysis): 1000mg (1500 IU)

2005 Annals of Int Med: “Meta-Analysis: High-Dosage Vitamin E Supplementation May Increase All-Cause Mortality” Three previous meta-analyses that did not consider the dose-dependent effect of vitamin E concluded that vitamin E was neither beneficial nor harmful. New Conclusion based on 19 randomized controlled trials: High- dosage (>=400 IU/d) vitamin E supplements may increase all-cause mortality and should be avoided.

Health Hopes of Vitamin E Heart Disease: Mixed results Cancer: Promising but not conclusive –Breast cancer: two opposing studies –Colon and G.I. cancer: probably no benefit –Prostate and bladder cancer: possible benefit Alzheimer’s: theoretical but not well studied

Vitamin E & Cataracts 1998: “Antioxidant vitamins and nuclear opacities: the longitudinal study of cataract” –Cataract risk reduced by ½ in Vit E supplement users –764 participant observational study (low significance) However, 1997: “Long-term supplementation with alpha- tocopherol and beta-carotene and age-related cataract” –No benefit to Middle-aged male smokers taking vitamin E supplements on the incidence of cataract formation