Vitamin E Side Effects

The risk of vitamin E side effects is not very high. If you are supplementing, it is worth educating yourself about what could happen if you take too much vitamin E. There are two areas you need to be concerned with: first, side effects related to blood clotting, and second, a recent set of controversial studies showing increased all-cause mortality with vitamin E supplementation. This article summarizes both of these issues and offers guidance in the area of vitamin E supplementation.

First, the upper limit for vitamin E intake recommended by the National Institute of Medicine's Dietary Reference Intakes is 1500 IU natural tocopherol or 1100 IU synthetic tocopherol. Below these levels, you are unlikely to see side effects.

The main concern with excess vitamin E intake is the increased risk of hemorrhage and diminished blood coagulation. Additionally, small premature infants are particularly sensitive to alpha-tocopherol, and should be supplemented only under medical supervision.

Vitamins E and K have some chemical similarities, but perform different functions in the body. But because they aren't too far apart, they can actually take on one another's chemical roles if present in large quantities. Vitamin K is an essential coenzyme in the blood coagulation pathway. When vitamin E supplementation increases circulating concentrations to very high levels, vitamin E and it's metabolites can interfere in the functioning of vitamin K. For this reason, vitamin E toxicity takes place within the chemical space of vitamin K.

A major risk around side effects exists within people who are vitamin K deficient. People who are vitamin K deficient or are taking anticoagulant therapy like Warfarin (Coumadin) have an increased risk of the side effects of vitamin E.

The second issue related to vitamin E side effects is a purported statistical increase in risk of all-cause mortality. This observation arose in a 2005 study by Miller, et al. which analyzed 19 clinical trials over a 38-year period. This study brought up considerable negative publicity for vitamin E supplementation. Subsequent re-analysis by Hathcock et al demonstrated that this increased risk is only a factor for people taking over 2000 IU/day, which is well beyond than the recommended upper limit.

To summarize, symptoms of vitamin E side effects involve hemorrhage and blood clotting due to interference in the vitamin K pathway. These issues should not show up below the recommended upper limit. Additional statistical risks from vitamin E also only become apparent in excessive dosage.

Picking the right dose of the right kind of vitamin E is the best way to avoid vitamin E side effects.