Every so often, we hear about another study that has confirmed or disputed the health benefits of alcohol consumption.

Just last week, you may have heard about an international study which links alcohol consumption to an increased risk of breast cancer in women and cancers of the oral cavity, larynx, and esophagus in men.

The increased risk of these cancers was relatively small in men and women who drank moderate amounts of alcohol. It's a good time to review what we know so far about how alcohol affects our health.

As with many media reports of health benefits or dangers, the answer to whether alcohol is good or bad for your health is, "it depends."

Many studies involving large populations have shown that moderate alcohol consumption reduces the risk of heart attacks and strokes by more than 40 percent. These benefits appear to extend to both men and women, to those with or without known coronary artery disease, to people with diabetes, and to adults at any age. Some studies have also shown that light to moderate drinking reduces the risk of developing type 2 diabetes.

Though moderate alcohol consumption has some proven benefits, there are times to avoid alcohol completely. Pregnancy is one such time, due to the risk of fetal alcohol syndrome, a series of birth defects including abnormal facial features, growth retardation, and mental retardation. 

Drinking before driving is another. Alcohol can seriously impair judgment (including that of celebrity drinkers) and the ability to react quickly. Excessive chronic alcohol consumption can also lead to liver diseases, heart failure, and high blood pressure.

Much of the heart-healthy benefit of alcohol is attributed to its capacity to raise blood levels of protective high density lipoprotein (HDL) cholesterol, which removes cholesterol from atherosclerotic arterial plaques that lead to heart attacks and strokes.

Alcohol may also slightly lower levels of harmful low density lipoprotein (LDL) cholesterol, which initiates the formation of atherosclerotic plaques, and C-reactive protein, a measure of inflammation within the arterial wall.

Many health-conscious Americans drink more red wine. This practice is based on the surprising finding that the French, who consume red wine regularly along with a diet high in unhealthy saturated fats, have no more cardiovascular disease than people on lower-fat diets.

However, most studies have shown that red wine does not protect the heart any more than white wine - or, for that matter, any more than a moderate intake of beer or hard liquor - so the benefits are apparently due to the alcohol content of these beverages.

All these benefits are associated with moderate alcohol intake. Everyone knows one danger of excessive drinking: liver damage leading to cirrhosis. Other, less recognized risks of heavy drinking include pancreatitis, high blood pressure, strokes, and severe heart damage (cardiomyopathy) that can affect young people. Excessive drinking may also increase the risk of breast cancer in women.

The fuzzy distinction between moderate and excessive drinking also contributes to the potential for misuse of alcohol. One drink per day for women and 1 or 2 drinks a day for men are considered moderate amounts of alcohol. (A drink is defined as a 12-ounce beer, 1 ounce of liquor, or a 5-ounce glass of wine.) To protect against cardiovascular disease, alcoholic beverages must be imbibed regularly - almost every day - not in heavy doses on weekends, for example. Binge drinking can cause atrial fibrillation (a type of irregular heartbeat) and cancel any benefits that moderate drinking may have on the cardiovascular system.

Even moderate alcohol intake raises blood triglyceride levels in people who already have high triglycerides (one of the fats in blood). Elevated triglyceride levels are common in the U.S., and increase the risk of coronary disease just like cholesterol.

My patients have often asked me whether it's all right to have a drink of wine with dinner. I tell them it's probably a good idea. But I follow the American Heart Association's recommendation and advise non-drinkers not to start drinking alcohol to improve their cardiovascular health. The benefits are not worth the risks.