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Red wine induces a prolonged reduction in plasma viscosity
A randomized trial in which a glass (5 ounces) of cabernet sauvignon or no alcohol were prescribed for 3 weeks each (with the order of administration assigned randomly) showed that plasma viscosity (a known determinant of atherosclerosis) was improved when the participants were assigned to consume red wine.

The authors state that moderate red wine consumption has been associated with decreased risk of coronary heart disease. Reduced plasma viscosity and fibrinogen levels have been launched as possible contributors to this risk reduction. The effect of moderate red wine consumption on plasma viscosity, however, has not been investigated in a prospective, randomized trial. The investigators evaluated the effect of moderate red wine consumption on plasma viscosity, fibrinogen concentration and fibrinogen subfractions.

Healthy, nonsmoking volunteers were assigned to consume one glass of red wine daily for 3 weeks in a prospective, randomized cross-over study. In a second 3-week period the volunteers abstained from alcohol use. The plasma viscosity, fibrinogen concentration and the distribution of the main fibrinogen subfractionswere determined at inclusion, after wine drinking, and after abstention.

Plasma viscosity was reduced by 0.026 and 0.024 mPa.s in the two groups (those given wine initially and thoseabstaining initially) following wine intake. The 95% confidence intervals were 0.009–0.043, P = 0.004, and 0.0083– 0.039, P = 0.003. The decrease in plasma viscosity following wine administration was maintained following 3 weeks of abstention. The fibrinogen concentration was reduced by 0.17 g/l following wine drinking in the group starting with abstention (95% confidence interval, 0.04–0.29, P = 0.01). The distribution ofthe fibrinogen subfractions remained unaltered.

The authors conclude that a daily glass of red wine for 3 weeks significantly reduces plasma viscosity. Fibrinogen concentrations are also significantly reduced when consumption was preceded by an abstention period.

The decreased viscosity levels were maintained after 3 weeks of abstention, suggesting a sustained viscosity lowering effect of red wine. Comments by professor R. Curtis Ellison: Blood that is more viscous moves more sluggishly through the arteries and tends to clot more easily, and higher viscosity has been associated with greater risk of developing atherosclerosis. This is the first randomized trial (among 80 subjects averaging 50 years of age) to test the effects of a daily glass of red wine (150 ml, or about 5 ounces of cabernet sauvignon) on blood viscosity, and showed significant reductions from red wine. Fibrinogen results were less clear, but many previous studies have shown that fibrinogen is decreased among consumers of alcohol.

Unfortunately, the investigators did not have a wash-out period, so previous alcohol intake of the participants (reported to be low) could have led to some of the differences seen according to whether wine or no alcohol was prescribed for the first 3 weeks. And there were no specific measures of compliance with the prescribed intervention, only self report. Nevertheless, the finding of improved viscosity of blood from a single glass of red wine per day is interesting, and suggests still another mechanism by which moderate drinking may result in less atherosclerosis and coronary disease.

Source: Jensen T, Retterstøl LJ, Sandset PM, Godal HC, Skjønsberg OH. A daily glass of red wine induces a prolonged reduction in plasma viscosity: a randomized controlled trial. Blood Coagul Fibrinolysis 2006;17:471–47

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