July 1, 1998 CHICAGO, Ill.--A partial answer to the question of how moderate drinking helps to protect against coronary heart disease may be found in a new University at Buffalo study linking alcohol consumption with improved insulin sensitivity.
Analysis of a large Italian database by UB epidemiologists showed that the prevalence of a condition precipitated by insulin resistance called Syndrome X, which is characterized by abnormal levels of triglycerides, HDL cholesterol, blood pressure and glucose--all risk factors for heart disease--was significantly higher among non-drinkers than drinkers.
Results also showed that Syndrome X incidence declined as alcohol consumption increased and that the effect seemed to be more pronounced in women than in men. The apparent beneficial effect of drinking peaked at the 3-to-4 drinks-per-day level for both men and women, however. Syndrome X incidence began to climb in women who consumed more than four drinks per day, findings showed.
Results of the study by Jian Liu, M.D. and Maurizio Trevisan, M.D., of UB's Department of Social and Preventive Medicine, were presented here today by Liu (June 26, 1998) at the annual meeting of the Society for Epidemiologic Research.
Insulin resistance is a condition in which the pancreas produces sufficient amounts of the hormone, but cells absorb it more slowly than normal, causing sugar (glucose) and insulin to accumulate in the blood. Insulin resistance may be exacerbated by a bad diet, lack of physical activity, genetic predisposition and being overweight, Trevisan said.
The symptoms that characterize Syndrome X put a severe strain on the heart and arteries, he noted. Knowing that moderate drinking lowers the risk of heart attack, the UB researchers sought to determine if a relationship existed between alcohol consumption and insulin sensitivity, using Syndrome X as a marker.
The results could shed light on one possible mechanism through which alcohol may lower the risk of heart disease, Trevisan said.
Trevisan and Liu analyzed data collected from 37,991 Italian men and women in nine epidemiologic studies that comprise the Risk Factor and Life Expectancy Group. Their analysis included information on the amount of alcohol consumed per day, along with measurements of blood pressure, triglycerides, HDL cholesterol and blood glucose, variables all related to insulin resistance.
Persons with Syndrome X were defined as having all of the following:
- Blood pressure greater than 140/90 mmHg, or taking anti-hypertensive medicine
- Triglycerides greater than 175 mg/dl for men and 133 mg/dl for women, or taking lipid-lowering medicine
- Blood glucose higher than 100 mg/dl for men and 95 mg/dl for women, or taking diabetes medicines, and
- HDL levels lower than 40 mg/dl for men and 46 mg/dl for women.
Alcohol consumption was rated as light (1-2 drinks per day), moderate (3-4 drinks per day) or heavy (more than 5 drinks per day). A drink was defined as 11.7 grams (about four ounces) of alcohol.
Results showed that of the 21,612 men in the study, 2.9 percent of drinkers fit the Syndrome X definition, compared to 3.6 percent of the non-drinkers. Among 16,379 women, the percentages of drinkers versus non-drinkers classified with Syndrome X were 2.79 percent versus 3.95 percent, respectively.
Trevisan said if these results are confirmed in follow-up studies, the next step will be to determine the mechanism by which moderate alcohol consumption increases insulin sensitivity.
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