A new study at Sahlgrenska Academy, University of Gothenburg, confirms that moderate alcohol consumption can protect against coronary heart disease. But only for the 15% of the population that have a particular genotype.

The study included 618 Swedes with coronary heart disease and a control group of 3,000 healthy subjects. The subjects were assigned to various categories based on the amount of alcohol they consumed (ethanol intake). Meanwhile, they were tested in order to identify a particular genotype (CETP TaqIB) that previous studies had found to play a role in the health benefits of alcohol consumption.

Protective effect The results, which have been published in Alcohol, confirm the findings of the earlier studies. Moderate consumption of alcohol helps protect people with the genotype against coronary heart disease.

"In other words, moderate drinking has a protective effect among only 15% of the general population," says Professor Dag Thelle, Professor Emeritus at Sahlgrenska Academy, University of Gothenburg.

Sweeping advice Thus, the researchers believe that the advice frequently given about the health benefits of moderate alcohol consumption is far too sweeping.

"Moderate drinking alone does not have a strong protective effect," says Professor Lauren Lissner, who also participated in the study. "Nor does this particular genotype. But the combination of the two appears to significantly reduce the risk of coronary heart disease."

Unknown mechanisms The genotype codes for the Cholesterylester transfer protein (CETP), which affects the 'good,' cardio-protective HDL cholesterol that helps remove excess lipids from the blood vessels. One hypothesis is that alcohol somehow affects the CETP in a way that benefits HDL cholesterol.

A second hypothesis is that alcohol contains healthy, protective antioxidants.

The researchers believe that one or both of the hypotheses may prove correct, but the mechanisms by which HDL cholesterol or antioxidants might act remain unknown.

"Our study represents a step in the right direction," Professor Thelle says, "but a lot more research is needed. Assuming that we are able to describe these mechanisms, it may be a simple matter one day to perform genetic testing and determine whether someone belongs to the lucky 15%. That would be useful to know when offering advice on healthy alcohol consumption. But the most important thing is to identify new means of using the body's resources to prevent coronary heart disease."