Vitamin E may protect against oxidative stress: Study

While the antioxidant power of vitamin E is well established, few human studies exist that support the effects of the vitamin E supplementation on the fluidity of the membrane of red blood cells (erythrocytes), said to be an indirect marker of oxidative stress.

New data published in Nutrition Research​ ​indicate that four weeks of supplementation with vitamin E were associated with significant improvements in erythrocyte membrane fluidity, as well as decreased red blood cell rupturing (erythrocyte hemolysis).

“The role of therapeutic doses of vitamin E in protection against certain diseases related to oxidative stress has been supported by epidemiological and experimental data, but vitamin E trials have yielded varied and contradictory outcomes,”​ wrote researchers from the Medical College of Qingdao University.

“The results of our study help to reduce this confusion.​

“Overall, our findings support the hypothesis that dietary supplementation of vitamin E can effectively increase erythrocyte resistance to oxidative stress and improve membrane fluidity in healthy aging subjects.”​

Vitamin E​

There are eight forms of vitamin E: four tocopherols (alpha, beta, gamma, delta) and four tocotrienols (alpha, beta, gamma, delta). Alpha-tocopherol is the main source found in supplements and in the European diet, while gamma-tocopherol is the most common form in the American diet.

The new study used supplements containing dl-α-tocopheryl acetate.

Study details​

The Chinese researchers recruited 180 health people aged between 55 and 77 to participate in their four-month double-blind, randomized trial. Participants were divided into four groups and randomly assigned to receive vitamin E in doses of 0, 100, 200, or 300 mg of dl-α-tocopheryl acetate per day.

At the end of the study results showed that blood levels of alpha-tocopherol had increased by 71, 78, and 95, respectively.

In addition, levels of malondialdehyde (MDA - a reactive carbonyl compound and a well-established marker of oxidative stress) were significantly decreased in all three vitamin E groups, said the researchers.

Erythrocyte hemolysis was also reduced in the vitamin E groups, with decreases ranging from 20 to 38%. The higher dose vitamin E groups had “dramatic improvements in erythrocyte membrane fluidity”​, added the researchers.

“Our results showed that vitamin E supplementation at all 3 dosage levels significantly decreased erythrocyte hemolysis. We also observed significantly improved EMF [erythrocyte membrane fluidity] after 4 months of vitamin E supplementation at the 200 and 300 mg/d dosages, presumably because vitamin E resides primarily in cell membranes where it protects polyunsaturated fatty acids from oxidative damage.”​

Source: Nutrition Research​​
Published online ahead of print, doi: 10.1016/j.nutres.2012.03.012
“Vitamin E supplementation protects erythrocyte membranes from oxidative stress in healthy Chinese middle-aged and elderly people”​
Authors: Y. Sun, A. Ma, Y. Li, X. Han, Q. Wang, H. Liang