Supplementation of diets with alpha-tocopherol reduces serum concentrations of gamma- and delta-tocopherol in humans

J Nutr. 2003 Oct;133(10):3137-40. doi: 10.1093/jn/133.10.3137.

Abstract

Despite promising evidence from in vitro experiments and observational studies, supplementation of diets with alpha-tocopherol has not reduced the risk of cardiovascular disease and cancer in most large-scale clinical trials. One plausible explanation is that the potential health benefits of alpha-tocopherol supplements are offset by deleterious changes in the bioavailability and/or bioactivity of other nutrients. We studied the effects of supplementing diets with RRR-alpha-tocopheryl acetate (400 IU/d) on serum concentrations of gamma- and delta-tocopherol in a randomized, placebo-controlled trial in 184 adult nonsmokers. Outcomes were changes in serum concentrations of gamma- and delta-tocopherol from baseline to the end of the 2-mo experimental period. Compared with placebo, supplementation with alpha-tocopherol reduced serum gamma-tocopherol concentrations by a median change of 58% [95% CI = (51%, 66%), P < 0.0001], and reduced the number of individuals with detectable delta-tocopherol concentrations (P < 0.0001). Consistent with trial results were the results from baseline cross-sectional analyses, in which prior vitamin E supplement users had significantly lower serum gamma-tocopherol than nonusers. In view of the potential benefits of gamma- and delta-tocopherol, the efficacy of alpha-tocopherol supplementation may be reduced due to decreases in serum gamma- and delta-tocopherol levels. Additional research is clearly warranted.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Ascorbic Acid / administration & dosage*
  • Dietary Supplements
  • Female
  • Humans
  • Male
  • Middle Aged
  • Placebos
  • Tocopherols / blood*
  • alpha-Tocopherol / administration & dosage*
  • alpha-Tocopherol / analogs & derivatives*
  • gamma-Tocopherol / blood*

Substances

  • Placebos
  • gamma-Tocopherol
  • alpha-Tocopherol
  • delta-tocopherol
  • Ascorbic Acid
  • Tocopherols