Red wine, grape juice and hypertension

The polyphenols in red wine may offset the damage that its alcohol content might cause and may actively lower blood pressure

According to the US Centers for Disease Control and Prevention, one in three American adults have hypertension and only 50% of those patients have it under control.

In natural medicine circles, the Mediterranean diet has been championed as heart healthy. One controversial aspect of the diet is its inclusion of red wine. True, the polyphenols in wine seem to contribute to the cardiovascular health, but alcohol is also known to raise blood pressure (BP). A study published in the journal Nutrients explored this 'red wine contradiction.'

To illuminate the relationship between the grape-derived polyphenols and BP, a research team from the Netherlands first developed capsules containing a grape juice extract (MegaNatural, Polyphenolics [Madera, CA, USA]) mixed with a red wine extract (Provinols, Seppic [Paris, France]) providing a polyphenol dose of 800mg per day.

They also prepared capsules that contained only the grape juice extract and capsules containing a placebo. The team then conducted a double-blind placebo-controlled crossover study with 60 mildly hypertensive participants who were not being treated for the condition.

Participants were randomised into one of three groups: (1) a control group treated with the placebo capsules, (2) a group treated with grape juice extract capsules, and (3) a group treated with the capsules containing the mixture of grape and wine extracts. All capsules looked alike. Outcome measures were ambulatory and office BP, flow-mediated vasodilation, arterial distention, platelet function and plasma lipoproteins.

The 10-week trial began with a 2-week run-in period followed by two 4-week intervention periods. During the run-in period, participants consumed six placebo capsules per day: 3 with breakfast and 3 with dinner. At the end of the trial, 24-hour ambulatory systolic/diastolic BPs were significantly lower in the grape-wine extract intervention (135.9 ± 1.3/84.7 ± 0.8mmHg, mean ± SEM) compared with the placebo (138.9 ± 1.3/86.6 ± 1.2mmHg). The grape juice extract alone had no effect on BP or any measures of vascular function.

These preliminary data suggest that the polyphenols in red wine may offset the damage that its alcohol content might otherwise cause, and may actively lower BP instead of raising it.