Correlates of serum alpha- and gamma-tocopherol in the Women's Health Initiative.

Purpose: There is increasing evidence that vitamin E (primarily alpha- and gamma-tocopherol) may reduce the risk of cardiovascular disease and some cancers, therefore it is important to understand factors that influence blood levels.

Methods: The correlates of serum alpha- and gamma-tocopherol were investigated among participants in the Women's Health Initiative (WHI), a 40-site disease prevention trial. Subjects were 1047 postmenopausal women aged 50-79 years, who provided fasting blood specimens and detailed information on diet, supplement use, and other factors at entry to the study (1994-96).

Results: Total serum cholesterol and triglycerides were highly correlated with serum alpha- and gamma-tocopherol concentrations and were controlled for in all analyses along with age, ethnicity and body mass index (BMI). Alpha and gamma-tocopherol were strongly negatively correlated (partial r = -0.69). The strongest predictor of serum tocopherols was average daily intake of vitamin E from supplements (partial r = 0.60 for alpha, r = -0.54 for gamma). Other factors associated with increased alpha- and/or decreased gamma-tocopherol concentrations were serum retinol and carotenoids, supplemental vitamin C, alpha-tocopherol intake from food, dietary fiber, and Hispanic ethnicity. Factors associated with lower alpha- and/or higher gamma-tocopherol concentrations included gamma-tocopherol intake from food, total fat intake, and BMI. Age, income, hormone use, and geographic location were "spuriously" associated with serum tocopherol levels through their association with supplement use, i.e., there was no such association among the subset of women not taking supplements.

Conclusions: Vitamin E intake from supplements and BMI are the major independent predictors of serum tocopherol levels in women, whereas dietary factors only play a small role.