Vitamin E Interactions

High-dose vitamin E may increase bleeding risk with blood thinners

High-dose vitamin E (alpha-tocopherol above 400 IU per day) inhibits platelet aggregation through a protein kinase C-dependent mechanism, producing prolonged bleeding times and abnormal results on platelet function analyzers (such as PFA-100, VerifyNow, and light transmission aggregometry). The effect is most pronounced when vitamin E is combined with aspirin or other antiplatelet agents and can interfere with workup for bleeding disorders.

Vitamin C regenerates the active form of vitamin E by donating an electron to the tocopheroxyl radical that forms after vitamin E scavenges a lipid free radical. The pair extends antioxidant capacity at the lipid-water interface of cell membranes.

Omega-3 fatty acids (EPA and DHA) are polyunsaturated and highly susceptible to oxidation, which can blunt their cardiovascular and anti-inflammatory benefits. Vitamin E (mixed tocopherols) acts as a lipid-soluble antioxidant that protects omega-3 fatty acids from peroxidation both during storage and after absorption.

Vitamin E and selenium work as complementary antioxidants. Selenium is the cofactor for glutathione peroxidase, which clears lipid peroxides, sparing vitamin E. Vitamin E in turn prevents lipid peroxidation, reducing demand on the selenium-dependent enzyme.