The development of heart and circulatory diseases is affected by the presence of risk factors. Smoking, diabetes, high blood pressure, obesity and a high cholesterol level are the most important risk factors.
Moderate alcohol consumption favourably affects some of these risk factors, such that the general risk of heart and circulatory disease is reduced.

Scientific research shows that moderate alcohol consumption mainly has a favourable effect on cholesterol levels and clotting. More research is required, especially on a large scale to further examine these hypotheses.

* Cholesterol metabolism

In the “Lipid Research Prevalence Study” "(1) the researchers came to the conclusion that an increase in HDL cholesterol, which is the “good cholesterol”, is responsible for the protective effects of alcohol on the heart and blood vessels. They also state that there is also a decrease in LDL cholesterol, the so-called bad cholesterol. This favourable effect on the fat concentrations is insufficient, however, to fully explain the positive effect of alcohol on the heart and blood vessels.
According to another study under the Honolulu Heart Program "(2) half of the favourable effect of alcohol on the heart and blood vessels is explained by the cholesterol hypothesis. They also state that there is a positive shift in the HDL cholesterol / LDL cholesterol ratio. A glass of beer or another alcoholic drink a day seems to be enough to favourably influence the cholesterol housekeeping, and this is in both women and men "(3)

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* Blood clotting

Alcohol makes its mark on the clotting mechanism in the sense that it reduces the concentration of fibrinogens, a substance involved in the formation of blood clots. In other words, the consumption of alcohol reduces the risk of clot formations (thrombosis) and thus the risk of clogging of the coronary arteries. It is however a very small effect. In order to reduce the risk of clot formation in the coronary arteries by 4%, a consumption of 10 grammes of alcohol a day is required.
Various studies confirm that moderate alcohol consumption somewhat reduces the risk of clot formation in blood vessels. However, they are often very small studies with only a dozen test subjects (4,5).

* Homocysteine

The blood contains a certain level of homocysteine, which is an amino acid, a building block of protein. When the concentration of homocysteine increases, the risk of heart and circulatory disease also increases. In other words, a surplus of homocysteine in the blood is a risk factor for heart and circulatory diseases. Now this risk mainly seems to occur in people with a shortage of vitamin B6, vitamin B12 and folic acid (6) As beer is rich in these vitamins it is assumed that moderate beer drinkers run less of a risk of increased homocysteine levels in the blood. More research is required, however, to confirm this favourable effect of beer.

References:
(1) Lipoproteins as mediators for the effects of alcohol consumption and cigarette smoking on cardiovascular mortality results from the Lipid Research Clinics follow up Study. Crique M.H. et al., Am. J. Epidemiology 1987;126:629-637.
(2) Lipoproteins and blood pressure as biological pathways for effects of moderate alcohol consumption on coronary heart disease. Langer R.D. et al; Circulation 1992;85:910-915.
(3) High density lipoproteins cholesterol and types of alcoholic beverages consumed among men and women. Parker D.R. et al; American Journal of Public Health; 86(7):1022-1027.
(4) Renaud S. Lancet 1992;339:1523-1526.
(5) Effects of moderate dose of alcohol with evening meal on fibrinolytic factors. Hendrickx H et al.; British Medical Journal 1994;308:1003-1006.
(6) Folate and vitamin B6 from diet and supplements in relation to risk of coronary heart disease among women. Rimm EB et al; JAMA 1998;279:359-364.