لخّصلي

Vitamin E, a fat-soluble antioxidant, exists in eight stereoisomers, with only α-tocopherol exhibiting significant bioactivity in humans. Natural d-α-tocopherol is more effective than synthetic dl-α-tocopherol. Its primary function is protecting cell membranes from free radical damage, particularly lipid peroxidation. While proposed for preventing various diseases (cancers, cardiovascular issues, etc.), high doses (400 IU or more daily) have been linked to increased mortality risk, unlike lower doses (200 IU or less). Therefore, high-dose, long-term supplementation requires caution pending further safety research.

Is a fat-soluble vitamin with high antioxidant potency. Vitamin E is a chiral compound with eight stereoisomers: α, β, γ, δ tocopherol and α, β, γ, δ tocotrienol. Only α-tocopherol is the most bioactive form in humans. Studies in both animals and humans indicate that natural dextrorotary d-α-tocopherol is nearly twice as effective as synthetic racemic dl-αtocopherol(20). Because it is fat-soluble, α-tocopherol safeguards cell membranes from damage by free radicals. Its antioxidant function mainly resides in the protection against lipid peroxidation. Vitamin E has been proposed for the prevention against colon, prostate and breast cancers, some cardiovascular diseases, ischemia, cataract, arthritis and certain neurological disorders.(21) However, a recent trial revealed that daily α-tocopherol doses of 400 IU or more can increase the risk of death and should be avoided. In contrast, there is no increased risk of death with a dose of 200 IU per day or less, and there may even be some benefit (22). Although controversial, the use of long-term vitamin E supplementation in high dose should be approached cautiously until further evidence for its safety is available.