Five days of supplementation with a gamma-tocopherol-rich mixture of tocopherols maintained vascular endothelial function – the function of the cells lining blood vessels, according to findings published in the Journal of Nutritional Biochemistry .
The vitamin E supplement was also associated with supporting blood flow in the arteries and a reduction in increases of malondialdehyde (MDA - a reactive carbonyl compound and a well-established marker of oxidative stress).
“This study demonstrates that short-term gamma-tocopherol-rich mixture of tocopherols supplementation in healthy men maintains vascular endothelial function that is otherwise impaired by postprandial hyperglycemia likely by decreasing lipid peroxidation […] without affecting inflammatory responses,” report researchers from the University of Connecticut (USA) and Changwon National University (South Korea).
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.
Led by Richard Bruno, the researchers recruited 15 health men with an average age of 22 to participate in their randomized, crossover study. The men were randomly assigned to receive the vitamin E supplement or no supplement for five days prior to fasting and then receiving 75 grams of glucose.
The vitamin E supplement provided 500 milligrams of gamma-tocopherol, 60 mg of alpha-tocopherol, 170 mg of delta-tocopherol, and 9 mg of beta-tocopherol (Archer Daniels Midland, USA).
Results showed that the glucose test produced significant increases in MDA levels, and decreases of 30-44% in blood flow, as measured by brachial artery flow-mediated dilation (FMD). However, vitamin E supplementation prevented such changes, said the researchers.
The researchers also report for the first time that vascular endothelial function was maintained in the men after consuming the vitamin E supplement.
No changes in inflammatory markers were observed, indicating that the potential benefits of the vitamin E mix were not related to anti-inflammatory activity.
“Our findings support that gamma-tocopherol-rich mixture of tocopherols is beneficial for maintaining vascular endothelial function in healthy young men,” wrote the researchers.
“Further study is needed to more fully define the specific mechanisms by which gamma-tocopherol-rich mixture of tocopherols maintains vascular endothelial function that is otherwise impaired by postprandial hyperglycemia. Moreover, long-term studies investigating the cardioprotective effects of gamma-tocopherol-rich mixture of tocopherols are also needed to examine its potential benefit as a strategy to mitigate CVD risk.”
Source: Journal of Nutritional Biochemistry
Published online ahead of print, doi: 10.1016/j.jnutbio.2012.04.015
“Supplementation of a γ-tocopherol-rich mixture of tocopherols in healthy men protects against vascular endothelial dysfunction induced by postprandial hyperglycemia”
Authors: E. Mah, S.K. Noh, K.D. Ballard, H.J. Park, J.S. Volek, R.S. Bruno