Polyphenol-rich cranberry juice may boost heart health by alleviating arterial stiffness, says a new study from the Boston and Tufts Universities.
Double-strength cranberry containing 835 milligrams of total polyphenols and 94 mg of anthocyanins was associated with improvements in a measure of arterial stiffness called carotid femoral pulse wave velocity, according to findings published in the American Journal of Clinical Nutrition.
On the other hand, the Boston-based scientists report no benefits from cranberry juice consumption were observed for other measures of vascular or cardiovascular function, including blood pressure or brachial artery flow-mediated dilation, a measure of endothelial dysfunction since a low value is indicative of a blood vessel's inability to relax.
“We did observe a highly significant effect of cranberry juice on stiffness of the central aorta, which is increasingly recognized as an important measure of vascular function with relevance to cardiovascular disease,” wrote the researchers, led by Boston University’s Joe Vita, MD.
“Overall, 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,” they added.
Established and emerging health benefits
Cranberry is most famous for its ability to fight urinary tract infections, something that has led to almost one third of parents in the US giving it to their children, according to a recent study.
In 2004 France became the first country to approve a health claim for the North American cranberry species Vaccinium macrocarpon, which states that it can 'help reduce the adhesion of certain E.coli bacteria to the urinary tract walls'.
Other health conditions that may benefit from cranberry include stomach health, with several reports indicating that the berry’s constituents may inhibit the adhesion of Helicobacter pylori in the stomach. H. pylori is the only bacteria that can survive in the acidic environment of the stomach and known to cause peptic ulcers and gastritis.
In addition studies have suggested that proanthocyanidin-rich cranberry extracts may inhibit the growth and spread of human oesophageal adenocarcinoma (a cancer in glandular tissue), or may prevent colon cancer via an anti-inflammatory mechanism.
The researchers performed two studies: The first was an acute pilot study with no placebo involving 15 participants; the second was a chronic placebo-controlled crossover study with 44 participants with coronary artery disease.
In the acute, non-placebo controlled, pilot study, the researchers reported that cranberry juice (480 mL) was associated with improvements in both brachial artery flow-mediated dilation, from 7.7 percent before ingestion to 8.7 percent four hours after ingestion, as well as digital pulse amplitude tonometry ratio from to 0.10 to 0.23.
However, in the placebo-controlled, cross-over study, no such changes were observed. Dr Vita and his researchers did record a reduction in carotid-femoral pulse wave velocity from 8.3 to 7.8 m/s.
“We emphasize that the research beverage contained twice the amount of cranberry juice in commercially available cranberry juice and that the amount of anthocyanins consumed during the study greatly exceeded the average daily intake in the United States,” noted the researchers.
“Additional studies will be needed to determine how cranberry juice reduces central aortic stiffness, but our finding of improved pulse wave velocity without a change in endothelial function may be consistent with an effect at the level of the arterial wall or a change in sympathetic tone,” they added.
The study was funded by cranberry giant Ocean Spray and the National Institutes of Health (NIH).
Source: American Journal of Clinical Nutrition