It is clear that heavy drinking is harmful to health. According to the Centers for Disease Control and Prevention (CDC), excessive alcohol use causes about 79,000 deaths every year in the United States.1 Excessive alcohol use is defined as more than one drink per day (on average) for women and more than two drinks per day (on average) for men. It can lead to many serious health problems including:1,2
- Cancers of the liver, mouth, throat, colon, esophagus and breast
- Cirrhosis of the liver
- Dementia
- Depression
- Heart disease
- Injury (including car accidents and firearm injuries)
- Stroke
However, we get mixed messages about the health effects of drinking low to moderate amounts of alcohol. Is having a glass of wine with dinner a few nights a week harmful or healthful? Are the health risks and benefits the same for everyone? Looking at the scientific evidence on drinking alcohol in moderation can help you weigh the risks and benefits for yourself.
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)
Alcohol and breast cancer risk
Having even just a few alcoholic drinks each week appears to modestly increase the risk of breast cancer.3-5 And, the more a woman drinks, the higher her risk of breast cancer appears to be.3-6 A pooled analysis of data from 53 studies found for each alcoholic drink consumed per day, breast cancer risk increased by about seven percent.6 Women who had two to three alcoholic drinks per day had a 20 percent higher risk of breast cancer compared to non-drinkers.6
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.2 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.7-8 Heavier women tend to have higher blood levels of estrogen and higher levels of estrogen are linked to an increased risk of breast cancer.9
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.4,5,15-17 One reason may be that, alcohol affects the way the body processes estrogen, causing estrogen levels to rise.10-11 These different effects of alcohol on estrogen in the body explain how it increases breast cancer risk.
Does folate play a role in the relationship between alcohol and breast cancer risk?
Some, but not all, studies show getting enough folate may help reduce the breast cancer risk related to alcohol.12-17 The nutrient folate is necessary for the body to copy and repair DNA. Drinking alcohol can reduce blood levels of folate. Low levels of folate may make it more likely that DNA is incorrectly copied when cells divide. Such errors can lead cells down a pathway to become cancerous.
Folate is part of a healthy diet and is found in foods such as oranges, orange juice and green leafy vegetables. And, most multivitamins and fortified breakfast cereals contain folic acid, the synthetic or man-made form of folate.
Benefits of low to moderate alcohol in healthy adults
If you drink only in moderation (less than one drink a day for women), alcohol may have some health benefits, including:2,18-23
- Lower risk of heart disease
- Lower risk of hypertension (high blood pressure)
- Lower risk of losing cognitive function in older age
- Lower risk of mortality (especially among women at increased risk of heart disease)
It is important to note that excessive alcohol drinking has no health benefits; only health risks. The health benefits of alcohol are limited to those who drink only in moderation.
However, you don’t have to drink alcohol to get these health benefits. Getting regular exercise and eating a healthy diet may help maintain cognitive function as well as lower your risk of heart disease and hypertension and even death.20,24-30
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.31-34
Conclusions
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.”
| Susan G. Komen for the Cure® recommends that you: |
| 1. Know your risk – Talk to your family to learn about your family health history – Talk to your health care provider about your personal risk of breast cancer 2. Get screened – Ask your health care provider which screening tests are right for you if you are at a higher risk – Have a mammogram every year starting at age 40 if you are at average risk – Have a clinical breast exam at least every three years starting at 20, and every year starting at 40 3. Know what is normal for you and see your health care provider right away if you notice any of these breast changes: – Lump, hard knot or thickening – Swelling, warmth, redness or darkening – Change in the size or shape of the breast – Dimpling or puckering of the skin – Itchy, scaly sore or rash on the nipple – Pulling in of your nipple or other parts of the breast – Nipple discharge that starts suddenly – New pain in one spot that doesn’t go away 4. Make healthy lifestyle choices – Maintain a healthy weight – Add exercise into your routine – Limit alcohol intake |
References
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