过量摄入维生素E似乎不会危及健康

Despite concerns that have been expressed about possible health risks from high intake¹ of vitamin E, a new review concludes that biological mechanisms² exist to routinely eliminate excess levels of the vitamin, and they make it almost impossible to take a harmful amount. No level of vitamin E in the diet or from any normal use of supplements should be a concern, according to an expert from the Linus Pauling Institute at Oregon State University. The review was just published in the Journal of Lipid Research.

 

"I believe that past studies which have alleged³ adverse⁴（相反的） consequences from vitamin E have misinterpreted the data," said Maret Traber, an internationally recognized expert on this micronutrient and professor in the OSU College of Public Health and Human Sciences.

 

"Taking too much vitamin E is not the real concern," Traber said. "A much more important issue is that more than 90 percent of people in the U.S. have inadequate⁶ levels of vitamin E in their diet."

 

Vitamin E is an antioxidant and a very important nutrient⁵ for proper function of many organs, nerves and muscles, and is also an anticoagulant（抗凝剂） that can reduce blood clotting⁷. 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.

 

In the review of how vitamin E is metabolized, researchers have found that two major systems in the liver work to control the level of vitamin E in the body, and they routinely excrete excessive amounts. Very high intakes⁸ achieved with supplementation only succeed in doubling the tissue levels of vitamin E, which is not harmful.

 

"Toxic⁹ levels of vitamin E in the body simply do not occur," Traber said. "Unlike some other fat-soluble vitamins such as vitamins A and D, it's not possible for toxic levels of vitamin E to accumulate in the liver or other tissues."

 

Vitamin E, because of its interaction with vitamin K, can cause some increase in bleeding, research has shown. But no research has found this poses a health risk.

 

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 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 deplete¹⁰ vitamin E levels.

 

Traber said she recommends taking a daily multivitamin that has the full RDA of vitamin E, along with consuming a healthy and balanced diet.

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