Despite the acknowledged benefits of drinking moderate quantities of alcohol, not all alcoholic drinks are beneficial, warn American physiologists. The positive effects are not due to the alcohol per se, they suggest, but to the polyphenolic plant-derived compounds found in the drinks.
Laura Mann and John Folts of the Department of Cardiovascular Medicine at the University of Wisconsin, USA, recently reviewed the reported benefits of drinking in moderation as a means of preventing coronary artery disease (CAD). The authors, writing in the journal Pathopysiology, report beneficial effects in all the areas of development of CAD, in particular: endothelial dysfunction, low density lipoprotein (LDL) oxidation by free radicals, platelets adhesion and aggregation, vascular smooth muscle cell proliferation and migration and inflammation involving monocytes and T cells.
The authors stress that not all alcoholic drinks are beneficial and that, most probably, the positive effect is not due to alcohol but to polyphenolic plant-derived compounds. Thus, relatively few alcoholic drinks are linked to reducing the risk of developing CAD.
In particular, red wine and dark-colored beers provide the kind of protection that makes a difference. In fact, spirits and liquor, together with white wine, have the opposite effect compared with red wine, and could behave as pro-oxidant, proinflammatory substances. Moreover, if moderate alcohol drinking is associated to a high-fat diet, the negative effects of high-fat intake can be considerably reduced.
Minna Hannuksela and colleagues of the Department of Internal Medicine at the University of Oulu in Finland have also reviewed the protective effects of alcohol in coronary heart disease in Pathophysiology.
They concentrate on recent findings on the effect of alcohol on lipid molecules that are present in small quantities in lipoproteins and proteins that circulate in association with lipoprotein particles, and analyse the effect of ethanol on lipoprotein metabolism.
Ethanol-induced modifications of lipids might influence the cells of the arterial wall and in particular the endothelium and protect against atherosclerosis, they report. It is well known, for instance, that the endothelium influences blood flow in the arteries by affecting nitric oxide (NO) production and artery diameter. High density lipoprotein (HDL) plasma concentration rises following alcohol consumption, while LDL concentrations fall. HDL activates nitric oxide synthase resulting in increased release of NO from endothelial cells producing the desired outcome of dilated arteries and increased blood flow.
Hannuksela's team ascribe the beneficial effect of NO to ethanol consumption, while Mann and Folts link increased NO production to the polyphenols contained in red wine (as the consumption of equivalent quantities of white wine or pure alcohol is reported to have no effect on NO production).
In both reviews, the beneficial effects of alcohol consumption are reported when alcohol is ingested in moderate quantities sustained over a long period of time. Acute ingestion (binge drinking) does not seem to produce equivalent positive results.
