09/08/2013 02:42 pm ET Updated Nov 08, 2013

A New Look at 'Low-Risk' Drinking

The risks vs. benefits of so-called "moderate" drinking continue to be controversial. Even a respected organization such as the Mayo Clinic offers cautious advice:

Drinking alcohol may offer some benefits, especially for your heart. On the other hand, alcohol may increase your risk of health problems and damage your heart

As a way of walking this fine line, Mayo offers what has come to be standard advice: Drink in moderation. But what, exactly, does that mean?

What Is Moderate, Low-Risk Drinking?

The National Institute on Alcohol Abuse and Alcoholism (NIAAA) defines "low-risk" drinking as no more than four drinks per day and 14 per week for men, and no more than three drinks per day and seven per week for women. Does that mean that there is no risk if a person limits him or herself to that much drinking? Not necessarily. It appears, for example, that depending on just how a person engages in so-called low-risk drinking can make a big difference.

Drinking and Cancer

A study recently published in the journal Alcoholism: Clinical and Experimental Research sheds important light on this issue of low-risk drinking, at least in women.

The authors of this new study point out that surveys conducted on the subject of drinking behavior tend to ask participants how many drinks per week they usually consume. The researchers then divide that by seven to come up with a figure of drinks per day. So, if a woman reports that she consumes 10 glasses of wine per week, it's assumed that she has two drinks per day on average. While this exceeds the NIAAA recommendations, many women would probably classify this as low-risk or "moderate" drinking and not be concerned. But that now looks like a false assumption.

This new study strongly suggests that it is not only the total number of drinks per week that a woman consumes, but the pattern of her drinking that matters. Specifically, a pattern of drinking four or more drinks on any given day was modestly associated with an increased risk of breast cancer. That was true even if a woman were to have four drinks on two occasions per week, and no drinks in between.

How It Works

Although more research will be required to better understand the mechanics of the connection between a pattern of consuming several drinks more on a few occasions as opposed to one or two drinks a day and subsequent cancer, the authors do offer a plausible explanation. Alcohol is metabolized in the body into a chemical called acetaldehyde, which is a known carcinogen. It is the consensus among those who study cancer and its treatment that it takes many years of exposure to a carcinogen before an actual cancer is detected. In addition, it appears that there is no such thing as completely "safe" drinking the human body is better able to metabolize low levels of alcohol -- say one drink per day. In contrast, when a person consumes three or four drinks on a given day (or in the course of an evening) it appears that the metabolic consequences may be quite different.

Playing it Safe

Of course, the safest course of action may turn out to be not drinking alcohol at all. But then, what about the possible benefits of "moderate" drinking? The safest course, given this new information, would seem to be to avoid drinking three or more drinks on any one occasion. In other words, one drink a night is one thing, three drinks on Friday night and four on Saturday night is another. Both average out to one drink per day over the course of a week, but these different drinking patterns may very well lead to very different consequences.

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