"Drinking alcohol in moderation – Is the glass half-full or half-empty?" (March 2011)
How much is one drink of alcohol?
Different types of alcoholic beverages contain different amounts of alcohol. One drink is defined as 0.6 ounces of alcohol, or:
...•12 ounces of beer (one bottle or can)
•5 ounces of wine (one glass)
•1.5 ounces of liquor (one shot)
7 beers per week=721 calories
7 shots of liquor per week=679 calories
7 servings of liqueur per week=1155 calories
7 glasses of wine per week=875 calories
7 Martinis per week=868 calories
Alcohol and breast cancer risk:
Having even just a few alcoholic drinks each week appears to modestly increase the risk of breast cancer. And, the more a woman drinks, the higher her risk of breast cancer appears to be. A pooled analysis of data from 53 studies found for each alcoholic drink consumed per day, breast cancer risk increased by about seven percent. Women who had two to three alcoholic drinks per day had a 20 percent higher risk of breast cancer compared to non-drinkers.
Why does alcohol increase the risk of breast cancer?
There are several ways that alcohol may play a role in breast cancer. Alcohol contains a lot of calories (and few nutrients). Among adults in the U.S., alcohol ranks fifth in top sources of calories. So, many of us are getting a lot of calories from alcohol and those extra calories can lead to excess weight and weight gain. The excess weight, in turn, can increase our risk of breast cancer. Heavier women tend to have higher blood levels of estrogen and higher levels of estrogen are linked to an increased risk of breast cancer.
However, in studies that assessed the link between alcohol and breast cancer risk, alcohol was found to increase risk independent of (by means not related to) body weight. One reason may be that, alcohol affects the way the body processes estrogen, causing estrogen levels to rise. These different effects of alcohol on estrogen in the body explain how it increases breast cancer risk.
Does drinking alcohol affect risk of recurrence or mortality for breast cancer survivors?
As we get older, heart health becomes especially important. This is true for everyone, including breast cancer survivors. We do not yet know if drinking alcohol in moderation has health benefits for breast cancer survivors. Study results are mixed. Some studies show no increased risk of breast cancer recurrence or breast cancer mortality, while others show a slight increase in risk.
No one should ever drink alcohol in excess. Drinking more than one drink per day (for women) and more than two drinks per day (for men) has no health benefits and many serious health risks, including breast cancer. However, if you drink only low to moderate amounts of alcohol, there can be some health benefits, especially for your heart. If you currently drink alcohol only in moderation, weighing these risks and benefits can help you make informed choices.
Susan Hankinson, Professor of Medicine at Harvard Medical School offers this advice. “Moderate alcohol intake is one lifestyle factor well documented to have varying health effects in women – the increase in breast cancer risk and decrease in heart disease risk are both very well confirmed. Until we learn more about the mechanism, and possible ways to limit or eliminate the small increase in breast cancer risk with alcohol use, it will be important for individual women to weigh these risks and benefits.”