Written by Chrystal Moulton, Staff Writer. This study demonstrated how alpha-tocopherol supplementation decreased plasma levels of gamma tocopherol, thus verifying that different forms of vitamin E compete for absorption in the intestine and that alpha-tocopherol is preferentially absorbed.
Alpha-tocopherol is a commonly supplemented form of vitamin E. However previous research has shown that taking too much of one form of vitamin E may reduce other forms in plasma. In fact the body preferentially stores alpha- tocopherol over other forms of vitamin E.
In the current study, researchers wanted to confirm previous findings. First, researchers analyzed blood samples of 86 elderly men and women with an average age of 71 ± 6.4 years old who were already a part of an epidemiological study in the area. They then recruited 8 healthy middle-aged adult males under 60 years (average age is not listed for this study group) old to test the effects of alpha-tocopherol supplementation on levels of gamma, beta, and delta tocopherol. Participants were instructed to take 400IU of alpha-tocopherol three times daily for 2 months. During the study, participants were not allowed to take any other supplements and were told to maintain their current diet. Blood was drawn before and after the two month study period.
Analysis of blood samples from the elderly participants in the epidemiological study demonstrated an inverse relationship between alpha-tocopherol and gamma-tocopherol (r=-.45, p<0.001). Observation of the samples from the healthy participants revealed a causal effect of alpha-tocopherol supplementation on the reduction of gamma-tocopherol. Before supplementation alpha-tocopherol concentration in plasma was 13.4 ± 4.0 µg/ml and 43.5 ± 18.0 µg/ml after supplementation (p<0.001). Gamma and beta-tocopherol concentration (γ + β) was 2.04 ± 0.63 µg/ml before supplementation and 0.79 ± 0.39 µg/ml after supplementation (p<0.001).
Through this study, researchers clearly confirmed the direct connection between alpha-tocopherol supplementation on gamma and beta tocopherol concentration in plasma. Researchers concluded that all forms of vitamin E compete for the same uptake receptors in the small intestine. However the body preferentially absorbs alpha-tocopherol over other forms of vitamin E.
Source: Handelman, Garry J., Lawrence J. Machlin, Karlotta Fitch, John J. Weiter, and Edward A. Dratz. “Oral α-tocopherol supplements decrease plasma γ-tocopherol levels in humans.” The Journal of nutrition 115, no. 6 (1985): 807-813.
© 1985 American Institute of Nutrition
Posted March 18, 2014.
Chrystal Moulton BA, PMP, is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Indianapolis, IN.
References:
- Handelman GJ, et al. Oral alpha-tocopherol supplements decrease plasma gamma-tocopherol levels in humans. J Nutr. 1985 Jun;115(6):807-13.
