Cranberry juice, frequently touted as a weapon against urinary-tract infections, may also be good for your heart. Researchers from Tufts and Boston University report that the polyphenols in cranberry juice could improve blood-vessel function in patients with coronary heart disease.
Their study, published in the American Journal of Clinical Nutrition, compared cardiovascular measurements in 44 patients who drank double-strength cranberry juice or a placebo for four weeks each, with a two-week break in-between. The cranberry-juice drink contained 54% juice, with a total 835 milligrams of polyphenol antioxidants; both beverages totaled about 16 ounces of liquid. Patients refrained from drinking other beverages high in polyphenols during the trial.
Testing immediately before and after drinking the juice or placebo and 12 hours later showed a decrease in arterial stiffness associated with the cranberry juice, while stiffness increased after the placebo drink. Other measures of blood-vessel health, such as dilation, did not change, although these did improve in a small, uncontrolled pilot study of cranberry juice only.
This research further substantiates a growing body of literature that polyphenols in general and flavonoids in particular can contribute to heart health, says Jeffrey B. Blumberg, PhD, director of Tufts HNRCA Antioxidants Research Laboratory and a co-author of the study. While much of these data have been drawn from experimental and observational studies, these results from a randomized clinical trial further strengthen the evidence of the health benefits from flavonoids as found in plant foods and beverages.
| Cranberry Considerations |
When shopping for cranberry juice, keep a keen eye on product and Nutrition Facts labels. Some cranberry juice drinks can be blends of multiple fruit juices and may not have a high cranberry content. Many cranberry products also contain added sugars to offset the natural tartness of the fruit, so be alert about the calorie count; a typical eight-ounce serving contains 30 grams of sugars and 137 calories. This sweetening typically brings cranberry juice only to levels similar to other fruit juices, however, Tufts Jeffrey Blumberg points out: Cranberry juice cocktail still contains less sugar and calories than 100% grape juice and 100% pomegranate juice, about the same as 100% pineapple juice and a bit more than 100% apple juice. Blumberg adds that these polyphenols are multifunctional. In the case of cranberries, they show not only cardiovascular benefits but also antibacterial functions. The cranberry polyphenols appear to fight bacteria, Blumberg suggests, by anti-adhesion mechanisms-preventing bacteria from sticking the bladder and other tissues.
TO LEARN MORE: American Journal of Clinical Nutrition, May 2011; abstract at www.ajcn.org/content/93/5/934.abstract. Cran-tastic!, Tufts University Health & Nutrition Letter, November 2010.