HealthDay News — Young and middle-age women who consume high levels of anthocyanins — the flavonoids present in red and blue fruits such as strawberries and blueberries — had a significantly reduced risk for myocardial infarction (MI), results of a large prospective study show.
Those in the highest quintile of anthocyanin consumption had a 32% decrease in risk of MI during 18 years of follow-up (HR=0.68; 95% CI: 0.49-0.96; P=0.03), Aedín Cassidy, PhD, of the Norwich Medical School at the University of East Anglia in the United Kingdom, and colleagues reported in Circulation.
Results of a food-based analysis showed that women who consumed three servings of strawberries or blueberries a week had a 34% decrease in MI risk (HR=0.66; 95% CI: 0.40-1.08; P=0.09) compared with women who rarely included these fruits in their diet.
Previous research has suggested that anthocyanins may have cardioprotective effects, but little is known about the influence of diet on young to middle-aged women with risk factors for coronary artery disease — like smoking and oral contraception use.
So the researchers analyzed data from 93,600 women enrolled in the Nurses’ Health Study II to determine the effect of dietary flavanoids, which are known to benefit endothelial function, on health outcomes.
At study enrollment in 1991, participants were aged 25 to 42 years. They completed food frequency and lifestyle questionnaires every four years for nearly two decades. During follow-up, there a total of 405 MI cases occurred at a median age of 48.9 years.
The 32% reduced MI risk among women in the highest quartile of anthocyanin consumption remained significant even after adjusting for risk factors including BMI, physical activity, saturated fat intake, use of caffeine and alcohol, and family history of MI.
Furthermore, when the researchers compared participants in the highest quintile of anthocyanin consumption to the lowest 10% quintile, there was a relative risk of 0.53 (95% CI: 0.33-0.86) for the high-intake group, suggesting the presence of a dose-response relationship.
This risk reduction persisted even when the researchers adjusted for total fruit and vegetable intake, suggesting “that the benefits are specific to a food constituent in anthocyanin-rich foods (including blueberries, strawberries, eggplants, blackberries, black currants) and not necessarily to nonspecific benefits among participants who consume high intakes of fruits and vegetables.”
However, the researchers noted that there may be other unidentified, potentially beneficial components in other fruits and vegetables that contribute to cardioprotection that a population-based studied is not powered to detect.
They called for more research to better understand anthocyanins’ mechanism of action in cardioprotection, as well as to further evaluate dose responses and longer-term clinical endpoints.