Cranberry's short- and long-term effects
All of the 59 people who took part in this two-part study had coronary artery disease, and many of them were taking medications to treat risk factors for heart disease, including high blood pressure, high cholesterol, and diabetes. The study was done in two parts:
- In the first part of the study, 15 people drank a single 16-ounce drink containing 54% cranberry juice--twice the amount found in commercially available cranberry juice cocktails.
- In the second part of the study, 44 people were assigned to drink either the 16 ounces of double-strength cranberry juice or placebo every day for four weeks.
- After a two-week break, their assignments were reversed for another 4 weeks.
Cranberry improves vascular health
Cranberry juice had positive but different effects on vascular health after both the single drink and the four weeks of regular consumption:
- Tests that measure how readily arteries dilate in response to specific triggers showed that arterial function improved within four hours after drinking the single glass of cranberry juice.
- Tests to measure arterial stiffness, but not arterial function tests, improved after four weeks of cranberry juice. The placebo drink had no effect on arterial function or stiffness.
Cranberries, like other colorful fruits, are rich in anthocyanins and other polyphenols, plant compounds that have strong antioxidant and anti-inflammatory properties. These compounds may well be responsible for the positive effects of cranberry juice on arterial health seen in this study, and the benefits of other antioxidant-rich foods on cardiovascular health seen in other studies.
In summarizing the importance of their findings, the study's authors said, "Our results may provide further support for the American Heart Association recommendation that cardiovascular disease risk may be reduced by a diet rich in fruit and vegetables, including cranberries."
Anthocyanins for heart health
In addition to cranberries, these are some anthocyanin-rich fruits to consider including in your regular diet to protect your heart and blood vessels:
- Grapes. Studies have consistently found that taking grapes regularly, particularly in the form of red wine, can reduce cardiac risk.
- Strawberries. Strawberry eaters have been found to have lower levels of C-reactive protein (a risk marker for heart disease) and lower risk of cardiovascular death.
- Blueberries. Eating blueberries also appears to reduce the risk of cardiovascular death.
- Chokeberries. There is early evidence that drinking chokeberry juice might improve arterial function.
- Cherries, raspberries, blackberries, and black currants. All are good sources of anthocyanins.
(Am J Clin Nutr 2011;93:934-40)