One Drink of Red Wine Or Alcohol Is Relaxing to Circulation, but Two Drinks Are Stressful

One drink of either red wine or alcohol slightly benefits the heart and blood vessels, but the positive effects on specific biological markers disappear with two drinks, say researchers at the Peter Munk Cardiac Centre of the Toronto General Hospital.

In a study entitled “Dose-related effects of red wine and alcohol on hemodynamics, sympathetic nerve activity, and arterial diameter”, published in the February edition of the American Journal of Physiology, Heart and Circulatory Physiology, researchers conducted a real-time study of thirteen volunteers to determine whether a red wine with a verified high polyphenol content differs from alcohol in its effects on specific markers associated with a greater risk of high blood pressure, coronary artery disease and heart failure.

A large number of population studies have shown a protective effect of light or moderate alcohol drinking against the risk of death and the development of heart disease. Many studies have also reported specific benefits of red wine.

Population surveys found lower rates of heart disease, despite high-fat diets, in some European countries where red wine was consumed regularly. Widely known at the French paradox, this has created a huge interest in exploring if and how red wine has a protective effect against heart disease.

However, the findings of this study showed virtually identical effects of red wine and alcohol on the specific markers tested. After one drink of either red wine or alcohol, blood vessels were more “relaxed” or dilated, which reduced the amount of work the heart had to do. But, after two drinks, the heart rate, amount of blood pumped out of the heart, and action of the sympathetic nervous system all increased. At the same time, the ability of the blood vessels to expand in response to an increase in blood flow diminished. This counteracted the beneficial effect of one drink of red wine or alcohol.

“We had anticipated that many of the effects of one ethanol drink would be enhanced by red wine. What was most surprising was how similar the effects were of red wine and ethanol. Any benefits that we found were not specific to red wine,” said Dr. John Floras, Director of Cardiology Research at the Peter Munk Cardiac Centre, and at Mount Sinai Hospital, in whose laboratory the study was performed. However, Dr. Floras cautioned this study measured the effects of these drinks on one occasion only. The effects of daily wine or alcohol intake may be quite different.

The laboratory of Dr. Floras, who holds the Canada Research Chair in Integrative Cardiovascular Biology and is a Professor of Medicine at the University of Toronto, and a Career Investigator of the Heart and Stroke Foundation, is one of the few in the world equipped to measure simultaneously a broad spectrum of factors such as blood pressure, heart rate, sympathetic nerve firing and arterial diameter.

Healthy, non-smoking adults who were not heavy drinkers or total alcohol abstainers were studied. Participants attended three separate morning sessions during which “standard” drinks of red wine, ethanol or water were administered at random, single-blind, two weeks apart. A 4-oz glass of wine (120 ml), and a 1.5-oz (44 ml) shot of spirits is considered to be one standard drink. All blood alcohol levels alcoholic were below .08, the legal limit for drivers.The Quality Assurance Laboratory of the Liquor Control Board of Ontario selected a moderately priced pinot noir with a verified high t-resveratrol content, a polyphenol compound found in plants, including red grapes, which exhibits antioxidant properties. Alcohol or substances in alcohol such as resveratrol may improve blood vessel function and also prevent platelets in the blood from sticking together, which may reduce clot formation and the risk of heart attack or stroke.