Low Serum Concentration of Vitamin E Linked to Physical Decline in Older Persons

Laurie Barclay
January 22, 2008 — Low serum concentration of vitamin E, an indicator of poor nutrition, is associated with subsequent physical decline among community-dwelling older adults, according to the results of a study reported in the January 23 issue of the Journal of the American Medical Association.
"Maintaining independence of older persons is a public health priority, and identifying the factors that contribute to decline in physical function is needed to prevent or postpone the disablement process," write Benedetta Bartali, RD, PhD, from Cornell University in Ithaca, New York, and colleagues. "The potential deleterious effect of poor nutrition on decline in physical function in older persons isunclear. . . . The purpose of this study was to determine whether a low concentration of specific micronutrients is associated with subsequent decline in physical function."
The investigators analyzed data from a longitudinal study of 698 community-dwelling persons 65 years or older who were randomly selected from a population registry in Tuscany, Italy. Baseline evaluation was performed from November 1, 1998, through May 28, 2000, and the 3-year follow-up evaluations from November 1, 2001, through March 30, 2003.
Decline in physical function during the 3-year follow-up was defined as a loss of 1 or more points in the Short Physical Performance Battery score. With the top 3 quartiles of each nutrient combined as the reference group, odds ratios were calculated for the lowest quartile. To confirm the validity of these results, the study authors used 2 additional and complementary analytical approaches.
Mean decrease in the Short Physical Performance Battery score was 1.1 point. Only a low concentration of vitamin E (< 1.1 μg/mL [< 24.9 μmol/L]) was significantly associated with subsequent decline in physical function, based on a logistic regression analysis with adjustment for potential confounders. Odds ratio for the association of lowest alpha-tocopherol quartile with at least a 1-point decline in physical function was 1.62 (95% confidence interval, 1.11 - 2.36;P = .01).
Baseline concentration of vitamin E was significantly associated with the Short Physical Performance Battery score at follow-up, in a general linear model with vitamin E analyzed as a continuous measure, after adjustment for potential confounders and baseline Short Physical Performance Battery score (β =.023; P = .01).
The strongest predictors of decline in physical function were age older than 81 years and vitamin E (in participants aged 70 - 80 years), based on classification and regression tree analysis. Physical decline occurred in 84% and 60%, respectively (misclassification error rate, 0.33).
"These results provide empirical evidence that a low serum concentration of vitamin E is associated with subsequent decline in physical function among community-living older adults," the study authors write.
Limitations of the study include bias by loss to follow-up, use of an Italian population–based sample limiting generalizability, vitamin D associated with decline in physical function in bivariate analysis but not in adjusted analyses, possible false-positive results because 6 micronutrient levels were tested, and possibly inadequate adjustments for multiple potential confounders.
"Although the findings from this epidemiological study cannot establish causality, they provide a solid base that low concentration of vitamin E contributes to decline in physical function," the study authors conclude. "Clinical trials may be warranted to determine whether optimal concentration of vitamin E reduces functional decline and the onset of disability in older persons with a low concentration of vitamin E."
The Invecchiare in Chianti study was supported by the Italian Ministry of Health and in part by the National Institute on Aging, National Institutes of Health. Funding for vitamin E assessment was provided by Bracco Imaging SpA, Italy. Some of the study authors have disclosed various financial relationships with the National Institute on Aging, the Yale Claude D. Pepper Older Americans Independence Center, and Yale University School of Medicine. The remaining study authors have disclosed no relevant financial relationships.
JAMA. 2008;299:308-315.