A daily glass of grape juice may help men with hypertension lower their blood pressure, according to results from a preliminary study presented in the US last week.
In the study, men with raised blood pressure who drank Concord grape juice for 12 weeks experienced a significant drop in both their systolic and diastolic blood pressures.
"This is one of the first randomised, double-blind, placebo-controlled studies to use a whole juice - in this case Concord grape juice," said study author Dr Kevin Maki, director of the Nutrition and Metabolism Research Unit at Radiant Research, Chicago.
"In our study, blood pressure was measured as part of the basic health information of the study participants. When we reviewed the data, we saw reductions of nearly six points in both systolic and diastolic blood pressure measurements among the hypertensive men drinking Concord grape juice. Those on the calorie-matched placebo showed no significant change."
The study, presented at the annual meeting of FASEB, the Federation for American Societies of Experimental Biology, in San Diego, looked at 80 healthy males, aged from 45 to 70. For 12 weeks, half drank an average of 12 ounces of Concord grape juice per day and half drank the same amount of a placebo beverage designed to look and taste like grape juice.
Median baseline systolic blood pressure was 132mm Hg. At the conclusion of the study, the 19 participants with above-median systolic blood pressure who drank Concord grape juice showed a drop from an average baseline systolic blood pressure of 142.7mm Hg to 137.0, and from 87.9 to 82.1mm Hg for diastolic blood pressure. The 17 participants with above-median blood pressure who consumed the placebo showed no change from baseline. The systolic and diastolic differences between treatments were significant.
"While additional studies are necessary to confirm these results, it is exciting that drinking Concord grape juice every day may be an easy way for hypertensive individuals to significantly lower their blood pressure," noted Maki.
US health experts estimate that lowering systolic blood pressure by five points would result in a 14 per cent reduction in deaths from stroke and a 9 per cent reduction from heart disease.
The study authors pointed to two previous clinical studies showing that consuming Concord grape juice improved arterial wall flexibility, as demonstrated by increased flow-mediated vasodilation, suggesting a possible explanation behind the reduced blood pressure.
Recent research has also shown the ability of purple grape juice to slow the oxidation of LDL cholesterol as well as inhibit the tendency of blood to clot. Both functions contribute to maintaining healthy cardiovascular function.
The study was funded by Welch Foods, an American maker of grape-based foods.