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.
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.
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.
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.
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.