They define moderate drinking as two to four drinks a day for men; one to two drinks for women.
"Heavy" drinking is anything beyond that. Light drinking is greater than zero but below the moderate amounts.
In the U.S., a standard drink is 12 ounces of regular beer, 8 ounces of malt liquor, 5 ounces of wine, or 1.5 ounces of liquor.
"Heavy drinkers should be urged to cut their consumption, but people who already regularly consume low to moderate amounts of alcohol should be encouraged to continue," write the researchers.
They included Augusto di Castelnuovo, ScD, of Catholic University in Campobasso, Italy.
The researchers pooled data from 34 observational studies conducted in Europe, the U.S., Australia, Japan, and China.
The studies looked at more than 1 million people in total, with participants reporting their drinking habits.
The studies lasted from six to 26 years.
During that time, moderate drinkers were about 18% less likely to die of any cause than teetotalers and light drinkers.
Other observational studies have linked moderate drinking to heart benefits. The new Italian report covers deaths from all causes, not just heart-related deaths.
Meanwhile, heavy drinkers were more likely to die of any cause, and the more they drank, the higher their risk of death.
That finding "confirms the hazards of excess drinking," write the researchers.
"Our data show that consumption of little amounts of alcohol leads to a reduction of mortality up to 18%," di Castelnuovo says in a news release.
"But after a certain number of glasses, things radically change," he notes.
People who drink too much increase their death risk "in relation to the amount of alcohol consumed," di Castelnuovo explains.
In short, if you're going to drink, don't overindulge. And, of course, don't drink and drive.
The researchers stop short of suggesting that teetotalers start drinking for health benefits or that light drinkers increase consumption.
They also caution that further studies are needed to check their findings.
SOURCES: Di Castelnuovo, A. Archives of Internal Medicine, Dec. 11/25, 2006; vol 166: pp 2437-2445. News release, Catholic University. CDC: "Alcohol and Public Health FAQ."
By Miranda Hitti
Reviewed by Louise Chang