Alpha-Tocopherol Supplements May Reduce Gamma-, Delta-Tocopherol Levels
BALTIMORETaking
alpha-tocopherol supplements may reduce serum levels of gamma- and
delta-tocopherol, according to researchers at Johns Hopkins University. Their
randomized, placebo-controlled trial was printed in the October issue of the Journal
of Nutrition (133, 10:3137-40, 2003) (www.nutrition.org).
Despite promising evidence from in vitro experiments and
observational studies, supplementation of diets with alphatocopherol has not
reduced the risk of cardiovascular disease and cancer in most large-scale
clinical trials, researchers wrote. One plausible explanation is that the
potential health benefits of alphatocopherol supplements are offset by
deleterious changes in bioavailability and/or bioactivity of other nutrients.
To test their theory, researchers assigned 184 adult
non-smokers to take 400 IU/d of RRR-alpha-tocopheryl acetate (a natural,
esterified form of alpha-tocopherol) or placebo for two months. At the end of
the study period, researchers measured changes in serum concentrations of gamma-
and delta-tocopherol from baseline. Compared with placebo, supplementation with
alphatocopherol reduced serum gamma-tocopherol concentrations by an average of
58 percent and reduced the number of individuals with detectable
delta-tocopherol concentrations.
Researchers concluded alpha-tocopherol supplementation may not
be efficacious due to reducing serum levels of the other two vitamin E isomers,
and they stated further research is clearly warranted.
Andreas Papas, Ph.D., president of YASOO Health Inc., adjunct
professor at the College of Medicine at East Tennessee State University and
senior scientific advisor at the Institute Harvard School of Epidemiology,
agreed with the Johns Hopkins researchers. Taking the whole complex is the way to get the full benefit
[of vitamin E], he said. That is now becoming quite a mainstream thesis.