Previous vitamin E supplement intake and memory impairment: A women’s health initiative ancillary study

Abstract

Background: There are plausible mechanisms by which Vitamin E could protect against dementia or cognitive loss, but studies of such associations have been inconsistent. A previous interim cross-sectional analysis of our data found serum alpha tocopherol ( -toc) , but not current Vitamin E supplement use, to be associated with memory impairment in older women. Objective: We examine the association of past supplemental and dietary Vitamin E intake with cognitive impairment in 544 women age 60 and over, who are participants in a Women’s Health Initiative (WHI) Ancillary Study. Methods: Vitamin E supplement intake was ascertained by interview, and dietary intake by food frequency questionnaire, at WHI baseline. Women were enrolled in the cognitive function ancillary study an average of 5.6 (SD 2.2) years later, at which time an extensive cognitive test battery was administered and supplement use practices updated. Cognitive tests were classified by predominant functional domain: Memory, Executive Function, Language, Attention, and Visual Function. Women scoring 2 standard deviations or more below established ageand education-specific norms on one or more tests in a given domain were considered to have signs of impairment in that domain. Results: In bivariate analyses, mean previous supplemental -toc intake was 24-60 mg/day lower in women with memory, executive function, or language impairment compared to those without, but the difference was statistically significant only for memory impairment (mean intake 84 vs 157 mg/day; p .02). In logistic regression models adjusting for age, education, race, and time between -toc and cognitive function measurements, previous supplemental -toc was inversely associated with risk of memory impairment (p .045) such that an additional 100mg/day -toc would be associated with a relative odds of memory impairment of 0.9. In similar models, neither previous dietary, nor current supplemental -toc, were associated with memory impairment. Conclusions: Previous, but not current supplemental -toc intake is associated with a modestly reduced risk of memory impairment in older women. Possible reasons could include: previous intake acting as a surrogate for duration; latency period between -toc exposure and effects on memory or need for exposure to occur at a particular time (e.g. midlife) for maximum benefit.