Abstract 10529: Randomized Double-Blind Parallel-Arm Placebo-Controlled 3-Month Trial of Purple Grape Juice for the Inhibition of Platelet Aggregation in Apparently Healthy People
Background: Purple grape juice (PGJ) consumption may improve factors associated with longevity and cardiovascular disease, including platelet function. Chronic PGJ use has not been evaluated in humans. A 3-month randomized double-blind parallel-arm placebo-controlled trial tested the hypothesis that daily PGJ consumption inhibits platelet aggregation.
Methods: Apparently-healthy volunteers (N=48) were randomized 1:1 to a 3-month treatment course of PGJ or a color-, taste-, and calorically-matched placebo drink at a dose of 3.5 ml/kg/day. PGJ and placebo were blinded to participants, investigators, and statisticians via a code held by Welch Foods Inc. until after the completion of statistical analyses. Platelet aggregation was measured using the agonist ADP (10 microM) in a light transmission aggregometer and compared between PGJ and placebo via the intent-to-treat paradigm.
Results: Mean age was 42±13 years (range 21-75); weight was 88±21 kg; and 57% were male. PGJ dose averaged 367±145 ml/day (12.4±4.9 ounces/day). Baseline characteristics did not differ by treatment assignment (p>0.05). Mean baseline ADP aggregation was 69.5% for PGJ and 73.6% for placebo (p=0.19). Change scores comparing 3-month ADP aggregation to baseline were 1.6%±16.2% for PGJ and -12.3%±17.8% for placebo (p=0.007). A trend of lower compliance in the PGJ arm during the third month of the study was found (88% vs. 97%, p=0.09), and on-treatment (>90% compliance) analysis found that ADP change scores did not differ at 3 months (PGJ: -1.7±14.6%, placebo: -13.0±18.5%; p=0.48). In contrast, the expected benefit of PGJ was qualitatively evident at 2 months (PGJ: -8.5±21.9%, placebo: -2.7±11.9%; p=0.26), although the difference was not significant.
Conclusion: Chronic PGJ treatment did not reduce ADP-induced platelet aggregation over a 3-month period. On-treatment analysis showed no difference between PGJ and placebo drink at 3 months when non-compliant participants were excluded. A small trend favoring PGJ was found at 2 months, but that minor benefit was obliterated during month 3 by decreased willingness to consume PGJ, suggesting a potential need for different designs to study cardiovascular benefits of PGJ.
- © 2011 by American Heart Association, Inc.