Serum ascorbic acid and cardiovascular disease prevalence in U.S. adults.

To examine the relation between serum ascorbic acid level and the prevalence of cardiovascular disease, we analyzed data from 6,624 U.S. men and women enrolled in the Second National Health and Nutrition Examination Survey. We calculated odds ratios and 95% confidence intervals to estimate the relative prevalence of cardiovascular disease, defined as self-reported coronary heart disease or stroke, or a diagnosis of peripheral vascular disease based on physical examination. Serum ascorbic acid levels were independently associated with prevalence of coronary heart disease and stroke; a 0.5-mg per dl increase in serum ascorbic acid level was associated with an 11% reduction in coronary heart disease and stroke prevalence. We also analyzed the relation of ascorbic acid, grouped into low to marginal, normal, and saturation serum categories, to cardiovascular disease. Compared with participants with low to marginally low serum ascorbic acid levels, we found a 27% decreased prevalence of coronary heart disease (95% confidence interval = 10-41%) and a 26% decreased prevalence of stroke (95% confidence interval = 3-44%) among participants in the highest serum ascorbic acid category. Serum ascorbic acid levels were not consistently associated with prevalence of peripheral vascular disease. These results are consistent with the hypothesis that increased ascorbic acid intake may decrease the risk of coronary heart disease and stroke.