Dietary flavonoid intake and incident coronary heart disease: the REasons for Geographic and Racial Differences in Stroke (REGARDS) study.

BACKGROUND

Flavonoids are dietary polyphenolic compounds with a variety of proposed beneficial cardiovascular effects, but rigorous prospective studies that examine the association between flavonoid intake and incident coronary heart disease (CHD) in geographically and racially diverse US samples are limited.

OBJECTIVE

With the use of the new, expanded USDA flavonoid database, we assessed the association between total flavonoid and flavonoid subclass intakes with incident CHD in a biracial and geographically diverse cohort, as well as effect modification by age, sex, race, and region of residence.

DESIGN

Participants were 16,678 black and white men and women enrolled in the REGARDS (REasons for Geographic and Racial Differences in Stroke) study, a national prospective cohort study. All participants were without CHD at baseline, and all completed a Block98 food-frequency questionnaire. Flavonoid intakes were estimated from USDA flavonoid databases, which were recently improved to address missing values for cooked foods and to adjust for flavonoid losses due to processing. Incident CHD events were participant reported and adjudicated by experts. Quintiles of flavonoid intake were examined as predictors of incident CHD by using Cox proportional hazards regression to obtain HRs. Tests for trend used the quintile medians.

RESULTS

Over a mean ± SD follow-up of 6.0 ± 1.9 y, 589 CHD events occurred. High flavonoid intake was associated with self-identified white race, exercise, not smoking, more education, and higher income. In models that adjusted for sociodemographic, health behavior, and dietary factors, there was an inverse association between anthocyanidin and proanthocyanidin intakes and incident CHD (HRs for quintile 5 compared with quintile 1-anthocyanidins: 0.71; 95% CI: 0.52, 0.98; P-trend = 0.04; proanthocyanidins: 0.63; 95% CI: 0.47, 0.84; P-trend = 0.02). There was no association between total flavonoid or other flavonoid subclass intakes and incident CHD.

CONCLUSIONS

Reported anthocyanidin and proanthocyanidin intakes were inversely associated with incident CHD. There was no significant effect modification by age, sex, race, or region of residence.