Science Has Determined the Exact Amount of Alcohol That Increases Breast Cancer Risk

A nightly glass of wine may be healthy for the heart—but it could spell trouble for other body parts, according to a new study.

Milleflore Images/Shutterstock, frantic00/ShutterstockDrinking as little as one glass of wine, beer, or any other type of alcohol a day may raise your risk of breast cancer, according to a new study by the American Institute for Cancer Research (AICR) and the World Cancer Research Fund. Approximately 252,710 cases of invasive breast cancer are diagnosed in women each year, and of that number, around 40,610 die, according to the American Cancer Society.

Based on their review of findings from 119 studies involving 12 million women from around the globe, the study authors found that as little as 10 grams of alcohol—that’s 3.3 ounces, less than a typical juice glass—is linked to an increased breast cancer risk of 5 percent for pre-menopausal women and 9 percent for post-menopausal women, according to The Columbian. Compare that amount to a standard drink, which contains 14 grams of alcohol, according to the National Institute on Alcohol Abuse and Alcoholism.

Alcohol consumption increases levels of estrogen and other hormones that are linked to the hormone that’s receptor positive for breast cancer. It can also damage DNA in cells, which increases risk for breast cancer, according to breastcancer.org.

Susan K. Boolbol, MD, chief of the Division of Breast Surgery at Mount Sinai Beth Israel Hospital, New York, told Medscape, “We have known about the link between alcohol and breast cancer as several studies have shown the association. The issue with those studies is that we did not have an exact amount of alcohol that was known to increase your risk. This report,” she adds, “clearly states that one drink per day will increase your risk. That is major news.”

On the plus side, the researchers did uncover a handful of lifestyle tweaks that can help counteract the heightened risk. Most notably, vigorous exercise like running and bicycling may reduce your breast cancer risk. According to The Columbian, active pre-menopausal women had an impressive 17 percent lower risk of developing malignancies compared to less active women, while post-menopausal women had a 10 percent decreased risk. Weight loss is also preventative: Women who are overweight or obese are at a higher risk of post-menopausal disease, including cancer. Should those women lose 10 percent of their weight, it could help reduce blood estrogen, inflammation, and other factors that are associated with breast cancer.

There’s some evidence that other lifestyle choices may help further reduce breast cancer risk; they include breastfeeding, eating dairy, limiting meat, and diets rich in calcium and foods that contain carotenoids (carrots, yams, watermelon, mangoes, etc.)

Anne McTiernan, MD, PhD, one of the report’s lead authors and a cancer prevention researcher at the Fred Hutchinson Cancer Research Center in Seattle, notes that while being physically active, keeping a healthy weight, and reducing alcohol intake will help you lower your breast cancer risk, you can’t control your genes, and you may still get diagnosed with breast cancer even if you run marathons and eat buckets of spinach and kale.

Ultimately, no level of alcohol use is safe when it comes to breast cancer, but if you’re going to drink, less is still better than more, Dr. McTiernan says.

Based on their conclusions, the AICR states that 1 in 3 cases could be prevented if women did not drink alcohol, were physically active, and maintained a healthy weight.

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