Objectives: Our objective was to prospectively examine the relation between vitamin C intake and risk of coronary heart disease (CHD) in women.
Background: Results from prospective investigations of the relation between vitamin C intake and risk of CHD have been inconsistent. The lack of clear evidence for a protective association despite a plausible mechanism indicates the need to evaluate further the association between vitamin C intake and risk of CHD.
Methods: In 1980, 85,118 female nurses completed a detailed semiquantitative food-frequency questionnaire that assessed their consumption of vitamin C and other nutrients. Nurses were followed up for 16 years for the development of incident CHD (nonfatal myocardial infarction and fatal CHD).
Results: During 16 years of follow-up (1,240,566 person-years), we identified 1,356 incident cases of CHD. After adjustment for age, smoking, and a variety of other coronary risk factors, we observed a modest significant inverse association between total intake of vitamin C and risk of CHD (relative risk [RR] = 0.73; 95% confidence interval [CI] 0.57 to 0.94). Among women who did not use vitamin C supplements or multivitamins, the association between intake of vitamin C from diet alone and incidence of CHD was weak and not significant (RR = 0.86; 95% CI 0.59 to 1.26). In multivariate models adjusting for age, smoking, and a variety of other coronary risk factors, vitamin C supplement use was associated with a significantly lower risk of CHD (RR = 0.72; 95% CI 0.61 to 0.86).
Conclusions: Users of vitamin C supplements appear to be at lower risk for CHD.