How much and how often people drink influences mortality risk

Mar 6 2008

How much and how often people drink - not just the average amount of alcohol they consume over time - independently influence the risk of death from several causes, according to a new study by researchers at the National Institutes of Health (NIH).

"Taken together, our results reinforce the importance of drinking in moderation. In drinkers who are not alcohol dependent, the majority of U.S. drinkers, alcohol quantity and frequency might be thought of as modifiable risk factors for mortality,” the researchers conclude.

“These findings underscore the importance of looking at drinking patterns when investigating alcohol-related health outcomes,” says Ting-Kai Li, M.D., Director of the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the NIH.

Rosalind A. Breslow, Ph.D., M.P.H., an epidemiologist in NIAAA's Division of Epidemiology and Prevention Research, and Barry I. Graubard, Ph.D., a statistician in the Division of Cancer Epidemiology and Genetics at the National Cancer Institute, examined data from a nationwide health survey conducted in 1988. Almost half of the nearly 44,000 people who participated in the survey identified themselves as current drinkers who had at least 12 drinks of alcohol during the previous year. By the end of 2002, more than 2,500 of these individuals had died. Drs. Breslow and Graubard compared their causes of death with the alcohol consumption patterns they reported in the survey. A report of their findings appears in the March, 2008 issue of Alcoholism: Clinical and Experimental Research.

The researchers found that, in men, alcohol frequency and quantity had opposite effects on cardiovascular mortality. The greater the amount of alcohol that men consumed on drinking days, the greater was their risk for death from cardiovascular disease. For example, men who had five or more drinks on drinking days had a 30 percent greater risk for cardiovascular mortality than men who had just one drink per drinking day. Alcohol quantity was also associated with increased mortality from cancer among men. On the other hand, frequency of drinking was associated with decreased risk for death from cardiovascular disease among men -- those who reported drinking 120 to 365 days per year had about 20 percent lower cardiovascular mortality than men who drank just one to 36 days per year. The current study was not designed to determine why drinking frequency might have a protective effect. Among women, frequent drinking was associated with a significantly increased risk of cancer, while increased quantity was associated with risk for mortality from all causes.

Previous studies have linked moderate drinking with reduced risk for death from cardiovascular disease, while heavier drinking has been linked with increased mortality. Such studies have typically measured individuals' average alcohol intake. A drawback of that approach, says Dr. Breslow, is that averaging obscures potential differences between people who sometimes drink heavily and those who consistently drink small amounts of alcohol.

“Average intake makes no distinction between the individual who has seven drinks one day each week, for example, and someone who has just one drink, every day,” explains Dr. Breslow. “Our study is the first to look at how both quantity and frequency components of alcohol consumption independently influence cause-specific mortality within a single cohort representing the US population.”

The researchers note that the U.S. Dietary Guidelines for Americans (http://www.health.gov/dietaryguidelines/dga2005/document/html/chapter9.htm) advise men to drink no more than two drinks per day and women to drink no more than one drink per day. Because women's bodies generally have less water than men's bodies, a given amount of alcohol is less diluted in a woman's body than in a man's. Consequently, when a woman drinks, the alcohol in her bloodstream typically reaches a higher level than a man's even if both are drinking the same amount.

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