A prospective study of dietary fiber intake and risk of cardiovascular disease among women

OBJECTIVES
This study was designed to examine the hypothesis that higher intake of dietary fiber is inversely related to the risk of cardiovascular disease (CVD) and myocardial infarction (MI) in a large prospective cohort of women.

BACKGROUND
Although dietary fiber has been suggested to reduce the risk of coronary disease, few prospective studies have examined the association between the types and amounts of dietary fiber and CVD risk, particularly among women.

METHODS
In 1993, we used a semi-quantitative food frequency questionnaire to assess dietary fiber intake among 39,876 female health professionals with no previous history of CVD or cancer. Women were subsequently followed for an average of six years for incidence of nonfatal MI, stroke, percutaneous transluminal coronary angioplasty, coronary artery bypass graft or death due to CVD confirmed by medical records or death certificates.

RESULTS
During 230,006 person-years of follow-up, 570 incident cases of CVD were documented, including 177 MIs. After adjustment for age and randomized treatment status, a significant inverse association was observed between dietary fiber intake and CVD risk. Comparing the highest quintile of fiber intake (median: 26.3 g/day) with the lowest quintile (median: 12.5 g/day), the relative risks (RR) were 0.65 (95% confidence interval [CI]: 0.51, 0.84) for total CVD and 0.46 (95% CI: 0.30, 0.72) for MI. Additional adjustment for CVD risk factors reduced the RRs to 0.79 (95% CI: 0.58, 1.09) for total CVD and 0.68 (95% CI: 0.36, 1.22) for MI. The inverse trends across categories generally remained, although they were no longer statistically significant. Inverse relations were observed between both soluble and insoluble fiber and risk of CVD and MI, and among those who had never smoked and those with body mass index <25.

CONCLUSIONS
A higher intake of dietary fiber was associated with a lower risk of CVD and MI, although the association was not statistically significant after further adjusting for multiple confounding factors. Nevertheless, these prospective data generally support current dietary recommendations to increase the consumption of fiber-rich whole grains and fruits and vegetables as a primary preventive measure against CVD.