"This is one of the first randomized, double-blind, placebo-controlled studies to use a whole juice--in this case Concord grape juice," explains study author Kevin Maki, Ph.D., Director, Nutrition and Metabolism Research Unit, 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 virtually no change."
The study, presented at the annual meeting of FASEB, the Federation for American Societies of Experimental Biology, looked at 80 healthy males, ages 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 132 mm 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 142.7 mm Hg to 137.0 (p< 0.05), and from 87.9 to 82.1 mm Hg (p<0.05) 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 (p<0.05).
"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," notes Maki.
The US National High Blood Pressure Education Program estimates that lowering systolic blood pressure by 5 points would result in a 14% reduction in deaths from stroke and a 9% reduction from heart disease.
The study authors point to two previous clinical studies showing that consuming Concord grape juice improved arterial wall flexibility (demonstrated by increased flow-mediated vasodilation) as suggesting a possible mechanism of action for 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 underwritten by Welch Foods Inc.
ABSTRACT # 693.10 CONCORD GRAPE JUICE REDUCES BLOOD PRESSURE IN MEN WITH HIGH SYSTOLIC BLOOD PRESSURE
David A. Mark, PhD1 and Kevin C. Maki, PhD2 1Welch Foods Inc., 575 Virginia Rd., Concord, MA 01742 2Radiant Research, Nutrition & Metabolism Unit, 515 N. State St., Chicago, IL 60610