Vitamin E
Vitamin E is a term used to refer to eight molecules, which are divided into two categories: tocopherols and tocotrienols. Each category is further divided up into alpha (α), beta (β), gamma (γ), and delta (δ) vitamers. The vitamer α-tocopherol is considered to be the ‘main’ vitamer, but the gammas (γ-tocopherol and γ-tocotrienol) are also popular research topics, due to their presence in the diet. Collectively, these compounds are called vitamin E. Vitamin E supplements almost always contain α-tocopherol.
The majority of vitamin E’s benefits come from avoiding a deficiency, but there are several instances where supplementation can offer additional benefits. Supplementing α-tocopherol is able to improve T-cell mediated immune function, which boosts the immune system.
Vitamin E also seems to be able to enhance the body’s antibody response to vaccinations. Vitamin E is particularly important for the elderly, since a deficiency is associated with a higher risk of bone fractures. Supplementing additional vitamin E, however, will not provide additional benefits to bone health. Vitamin E may also be able to protect against age-related cognitive decline, but further research is needed before supplementation can be recommended, specifically for Alzheimer’s and Parkinson’s treatment.
Vitamin E was one of the first two antioxidant compounds to be sold as dietary supplements, the second being vitamin C. It is sometimes used as the ‘reference’ antioxidant compound when fat soluble compounds are being researched. Vitamin E may function as a signaling molecule within cells and for phosphate groups.
Since the majority of vitamin E’s benefits are associated with low doses slightly above the Recommended Daily Allowance (RDA), vitamin E supplementation is not always necessary. Dietary changes can usually prevent a vitamin E deficiency and eliminate the need for supplementation. Sesame seeds in particular are a good source of tocotrienols, as well as sesamin, which improves the retention of vitamin E. High-dose long-term vitamin E supplementation (above 400IU per day), however, may be associated with increased risk of death and increased risk of prostate cancer.
Dosage
Vitamin E supplements should contain d-alpha-tocopherol. Avocados, olives, vegetable oils and almonds are all high in vitamin E.
Although many research protocols use milligrams of vitamin E, most commercial products are sold in international units (IU). One IU natural vitamin E equals 0.67 mg d-alpha-tocopherol and one IU of synthetic vitamin E equals 0.45 mg d-alpha-tocopherol.
Maintaining adequate levels of vitamin E in the body can be achieved through very low daily doses of 15mg (22.4 IU) or less. This dose of vitamin E can be acquired through the diet, making supplementation unnecessary in many cases. An elderly person supplementing vitamin E to improve immunity may benefit from a 50-200mg dose.
In regards to an upper limit, while doses above 400IU α-tocopherol (268mg) are well tolerated in the short term, it is the smallest dose associated with potential long-term adverse effects. If taking vitamin E as a daily supplement for no specific purpose (ie. as part of a multivitamin), then up to 100IU could be seen as a reasonable upper limit.
Safety
Low-dose vitamin E is safe to supplement, but it should not be mixed with coumarin-based anticoagulants like warfarin, as this may increase the risk of bleeding.