Context Dietary composition may affect insulin secretion, and high insulin levels,
in turn, may increase the risk for cardiovascular disease (CVD).Objective To examine the role of fiber consumption and its association with insulin
levels, weight gain, and other CVD risk factors compared with other major
dietary components.Design and Setting The Coronary Artery Risk Development in Young Adults (CARDIA) Study,
a multicenter population-based cohort study of the change in CVD risk factors
over 10 years (1985-1986 to 1995-1996) in Birmingham, Ala; Chicago, Ill; Minneapolis,
Minn; and Oakland, Calif.Participants A total of 2909 healthy black and white adults, 18 to 30 years of age
at enrollment.Main Outcome Measures Body weight, insulin levels, and other CVD risk factors at year 10,
adjusted for baseline values.Results After adjustment for potential confounding factors, dietary fiber showed
linear associations from lowest to highest quintiles of intake with the following:
body weight (whites: 174.8-166.7 lb [78.3-75.0 kg], P<.001;
blacks: 185.6-177.6 lb [83.5-79.9 kg], P = .001),
waist-to-hip ratio (whites: 0.813-0.801, P = .004;
blacks: 0.809-0.799, P = .05), fasting insulin adjusted
for body mass index (whites: 77.8-72.2 pmol/L [11.2-10.4 µU/mL], P = .007;blacks: 92.4-82.6 pmol/L [13.3-11.9 µU/mL], P = .01) and 2-hour postglucose insulin adjusted for body
mass index (whites: 261.1-234.7 pmol/L [37.6-33.8 µU/mL], P = .03; blacks: 370.2-259.7 pmol/L [53.3-37.4 µU/mL], P<.001). Fiber was also associated with blood pressure
and levels of triglyceride, high-density lipoprotein cholesterol, low-density
lipoprotein cholesterol, and fibrinogen; these associations were substantially
attenuated by adjustment for fasting insulin level. In comparison with fiber,
intake of fat, carbohydrate, and protein had inconsistent or weak associations
with all CVD risk factors.Conclusions Fiber consumption predicted insulin levels, weight gain, and other CVD
risk factors more strongly than did total or saturated fat consumption. High-fiber
diets may protect against obesity and CVD by lowering insulin levels.