Cardiac Benefits of Red Wine Not From the Alcohol

Drinking moderate amounts of nonalcoholic red wine -- but not its intoxicating equivalent -- lowered blood pressure in men with a high cardiovascular risk, a randomized, crossover study showed.

After 4 weeks of drinking the nonalcoholic wine, blood pressure fell by an average of 5.8/2.3 mm Hg (P menor 0.02), according to Ramon Estruch, PhD, of the University of Barcelona in Spain, and colleagues.

In contrast, drinking standard red wine for 4 weeks and gin during another 4-week period had no significant effect, although blood pressure did decrease a bit with the wine, the researchers reported online in Circulation Research. The changes in blood pressure with nonalcoholic red wine correlated significantly with changes in plasma nitric oxide, which increased by 4.1 µmol/L (P=0.041). Nitric oxide levels were not affected by the alcoholic beverages.

"Therefore, the blood pressure-lowering and nitric oxide-raising effects should be attributed to the red wine polyphenols and not to alcohol, which seems to counteract the effects of the nonalcoholic fraction of red wine," Estruch and colleagues wrote. "The daily consumption of dealcoholized red wine could be useful for the prevention of low-to-moderate hypertension," they concluded.

Moderate alcohol consumption has been associated with reduced cardiovascular risk, and red wine in particular is believed to be protective because of the high polyphenol content.

In vitro and experimental studies have suggested that the polyphenols found in red wine might lower blood pressure and increase endothelial nitric oxide, but the effects in humans had remained unclear.

The current study included 67 men (mean age 60) who had a high cardiovascular risk, defined as the presence of diabetes or at least three cardiovascular risk factors. After a 2-week, alcohol-free, run-in period, the men were randomized to complete three 4-week intervention periods -- without washout periods in between -- while maintaining a constant diet:

• 30 grams of alcohol per day in the form of red wine (about 9 ounces)
• About 9 ounces of nonalcoholic red wine per day
• 30 grams of alcohol per day in the form of gin (about 3.4 ounces)

The nonalcoholic and alcoholic red wines contained similar amounts of polyphenols. Gin does not contain polyphenols. During the study, there were no significant changes in body mass index, waist-to-hip ratio, or heart rate. The only significant changes observed were in systolic and diastolic blood pressure and plasma nitric oxide when the men were consuming nonalcoholic red wine. The researchers found significant differences in blood pressure and nitric oxide when comparing the nonalcoholic red wine group with the gin group. 

Although the reduction in blood pressure with nonalcoholic red wine was modest, decreases of 4 or 2 mm Hg in systolic or diastolic blood pressure, respectively, have been associated with a 14% relative reduction in the risk of coronary heart disease and a 20% relative reduction in stroke risk, lending clinical significance to the findings, according to the authors. The results of the study were largely the same when excluding individuals with hypertension and those taking antihypertensives, the researchers reported.

They acknowledged some limitations of the study, including the lack of information on the effects of longer-term consumption of the various drinks, the lack of measurements of endothelial function, and the inability to pinpoint the specific substances in red wine responsible for the observed effects.

Tomado de MedPage Today