According to a new US review, biological mechanisms exist to routinely eliminate potential excess levels of vitamin E, and they make it almost impossible to take a harmful amount.
In the review of how vitamin E is metabolized, two major systems in the liver were identified that work to control the level of vitamin E in the body, and they routinely excrete excessive amounts (1). Very high in-takes achieved through supplementation only succeed in doubling the tissue levels of vitamin E, which is not harmful. The mechanisms for the preference for alpha-tocopherol relative to the eight naturally occurring forms of vitamin E largely depend upon the liver. They include both a preferential secretion of alpha-toco-pherol from the liver into the plasma for its transport in circulating lipoproteins for subsequent uptake by tissues, as well as the preferential hepatic metabolism of the other forms of vitamin E.
The researchers commented that levels of vitamin E in the body can never become toxic. It is not possible for toxic levels of vitamin E to accumulate in the liver or other tissues, despite concerns that have been expressed about possible health risks from a high intake of vitamin E. Past studies that have alleged adverse consequences from vitamin E have misinterpreted the data, they noted. Because of its interaction with vitamin K, vitamin E can cause an increase in bleeding, research has shown, but no research has found that this poses a health risk. Thus, an increased level of vitamin E in the diet or from any normal use of supple-ments should be of no concern.
On the other hand, vitamin E performs many critical roles in optimum health. It protects polyunsaturated fatty acids from oxidizing, may help protect other essential lipids, and has been studied for its possible value in many degenerative diseases. Higher than normal intake levels may be needed for some people who have certain health problems, and smoking has also been shown to deplete vitamin E levels, the scientists added. While taking too much vitamin E is not a real concern, a much more important issue is that more than 90% of people in the US have inadequate levels of vitamin E in their diet.
Vitamin E is an antioxidant and a very important nutrient for the proper functioning of many organs, nerves and muscles. It is also an anticoagulant that can reduce blood clotting. It can be found in oils, meat and some other foods, but is often consumed at inadequate dietary levels, especially with increasing emphasis on low-fat diets.