Myocardial Infarction Risk in Women Reduced With Intake of Berries

Young and middle-aged women who regularly eat flavonoid-rich berries can reduce their risk of myocardial infarction (MI), according to a large prospective study widely reported in the media.

Blueberries and strawberries contain high concentrations of anthocyanins, a flavonoid shown to help lower blood pressure and improve endothelial function.

“All fruits and vegetables are likely to be beneficial, but in our study we found particular benefit to blueberries and strawberries,” senior author Eric Rimm, ScD, Associate Professor in the departments of epidemiology and nutrition at the Harvard School of Public Health, told ConsultantLive.

In the study, published online in Circulation on January 15, the risk of MI in women whose anthocyanin intake was in the highest quintile was decreased by 32% during 18 years of follow-up. In addition, the risk of MI was decreased by 34% in women who ate more than 3 servings of berries a week compared with women who rarely ate berries.

Biochemists and food scientists had reported strong biological effects of these flavonoid compounds in small studies of short duration, but the long-term effect on heart disease had not been examined in detail, said Dr Rimm.

The researchers looked at outcomes for 93,600 women enrolled in the Nurses’ Health Study II who reported their consumption of various foods and their lifestyle factors every 4 years. At enrollment in 1991, patients ranged in age from 25 to 42 years. During almost 2 decades of follow-up, there were 405 cases of MI, occurring at a median age of 48.9 years.

After reviewing food frequency and lifestyle questionnaires, the researchers found that women who consumed high levels of anthocyanins were less likely to smoke cigarettes, were more physically active, and had lower fat and higher fiber intake.

The 32% reduction in MI risk was seen after adjustment for multiple factors, including body mass index, physical activity, saturated fat intake, use of caffeine and alcohol, and family history of MI, said Dr Rimm. Even adding hypertension, dyslipidemia, diabetes mellitus, and other conditions to the analytical model did not significantly change the risk estimate.

The potential beneficial effects of anthocyanins may be particularly important for younger women. “When younger women have MIs they may be of different origin than those in the older population,” said Dr Rimm. “Younger women tend to have less atherosclerosis or more dysfunction of the coronary arteries. Anthocyanins act specifically in the arterial lining and may prevent inflammation and hyperactivity.”

Intake of other types of flavonoids did not significantly lower the risk of MI. Adjustment for additional dietary factors, such as total fruit and vegetable consumption, also did not alter the risk.

The researchers noted “that the benefits are specific to a food constituent in anthocyanin-rich foods (including blueberries, strawberries, eggplants, blackberries, and black currants) and not necessarily to nonspecific benefits among patients who consume high intakes of fruits and vegetables.”

The message for primary care physicians, according to Dr Rimm: “No single food is a magic bullet that will negate other bad habits, but berries sure seem to be an important part of a healthy diet.”

Media Links
New York Times: “Berries Lower Heart Risk”
The Boston Globe: “Which Fruits Best Lower Young Women’s Risk of Heart Disease?”
The Washington Post: “Antioxidants in Certain Fruits May Help Protect the Hearts of Younger Women”
The Huffington Post: “Strawberries and Blueberries Could Decrease Women’s Heart Attack Risk: Study”
ABC News: “Study: Berries Lower Heart Attack Risk for Women”