[Effect of ethanol on metabolic syndrome]

Metabolic syndrome is characterized by a group of risk factors for cardiovascular diseases, such as abdominal obesity, low high-density lipoprotein (HDL) cholesterol, elevated triglycerides, elevated arterial blood pressure, insulin resistance or impaired glucose tolerance. A number of studies focused on the relationship between alcohol consumption and prevalence of metabolic syndrome and its individual components. Ethanol can either aggravate the syndrome or prevent it--this depends primarily on the amounts and types of alcohol beverages consumed. It is commonly believed that moderate alcohol consumption is associated with a decreased incidence of metabolic syndrome and beneficial effects on plasma lipid levels, waist circumference and fasting plasma glucose. Of all the components of metabolic syndrome, the most beneficial effect of ethanol arises from an increase in plasma HDL cholesterol levels. The relationship between alcohol consumption and incidence of metabolic syndrome is more pronounced among red wine drinkers because polyphenoles contained in red wine increase the activity of endothelial nitric oxide synthase (eNOS), which plays a key role in the pathogenesis of metabolic syndrome. Decreased activity of this enzyme contributes to the development of insulin resistance, arterial hypertension and dyslipidemia. Stimulation of eNOS activity, which participates in the transport of HDL molecules, may provide an explanation for the mechanism of the increase in plasma levels of this particular lipid fraction in response to ethanol. Endothelial nitric oxide synthase requires the presence of antioxidants, which prevent both inactivation of nitric oxide in the reaction with peroxide anions and the accumulation of peroxynitrates.