Antioxidant vitamins and mortality in older persons: findings from the nutrition add-on study to the Medical Research Council Trial of Assessment and Management of Older People in the Community

Abstract

Background: Older persons are at risk of both poor nutrition and increased oxidative stress. Plasma ascorbate concentrations fall with increasing age, and concentrations of other antioxidants may also be reduced.

Objective: The goal was to examine the association between antioxidants and mortality in older persons.

Design: We randomly selected persons aged 75-84 y from the lists of 51 British family practitioners taking part in a randomized trial of assessment of older persons. A total of 1214 participants provided a blood sample and were interviewed about their usual diet with the use of a food-frequency questionnaire. Statistical analyses were based on deaths after a median of 4.4 y of follow-up, and hazard ratios were estimated for quintiles of dietary or blood antioxidants.

Results: We found strong inverse trends for blood ascorbate concentrations with all-cause and cardiovascular disease mortality, which were only marginally reduced after adjustment for confounders or supplement use. Those in the lowest fifth (< 17 micromol/L) had the highest mortality, whereas those in the highest fifth (> 66 micromol/L) had a mortality risk nearly half that (hazard ratio = 0.54; 95% CI: 0.34, 0.84). Similar results were found after the exclusion of those subjects with cardiovascular disease or cancer at baseline (hazard ratio = 0.51; 0.28, 0.93). In fully adjusted models, there was no evidence for an influence of alpha-tocopherol, beta-carotene, or retinol on total mortality. Dietary antioxidants measured by the food-frequency questionnaire were not associated with all-cause or cardiovascular disease mortality.

Conclusion: Low blood vitamin C concentrations in the older British population are strongly predictive of mortality.