Vitamin C status and mortality in US adults.

ABSTRACT

BACKGROUND: Low vitamin C status may increase the risk of mortality from cancer and cardiovascular disease. OBJECTIVE: The objective was to test whether an association existed between serum ascorbate concentrations and mortality and whether the association was modified by cigarette smoking status or sex. DESIGN: Serum ascorbate concentrations were measured in adults as part of the second National Health and Nutrition Examination Survey (1976-1980). Vital status was ascertained 12-16 y later. RESULTS: The relative risk (RR) of death, adjusted for potential confounders, was estimated by using Cox proportional hazards models. Men in the lowest (<28.4 micromol/L) compared with the highest (>/=73.8 micromol/L) serum ascorbate quartile had a 57% higher risk of dying from any cause (RR 1.57; 95% CI 1.21, 2.03) and a 62% higher risk of dying from cancer (RR 1.62; 95% CI 1.01, 2.59). In contrast, there was no increased risk among men in the middle 2 quartiles for these outcomes and no increased risk of cardiovascular disease mortality in any quartile. There was no association between serum ascorbate quartile and mortality among women. These findings were consistent when analyses were limited to nonsmokers or further to adults who never smoked, suggesting that the observed relations were not due to cigarette smoking. CONCLUSIONS: These data suggest that men with low serum ascorbate concentrations may have an increased risk of mortality, probably because of an increased risk of dying from cancer. In contrast, serum ascorbate concentrations were not related to mortality among women.