It only takes one glass of alcohol to put a woman at a higher risk for breast cancer, according to a new report.

Researchers uncovered that a small glass of wine or beer, which contains about 10 grams of alcohol, can boost a woman’s premenopausal cancer risk by 5 percent.

The number goes up to 9 percent for postmenopausal women.

Standard drinks include about 14 grams of alcohol.

Both risk figures are statistically significant, according to Dr. Anne McTiernan, a cancer prevention expert at the Fred Hutchinson Cancer Research Center, and lead author of the report.

It was released by the American Institute for Cancer Research (AICR) and the World Cancer Research Fund (WCRF).

The report also found that moderate exercise may be able to lower the risk of breast cancer in pre- and postmenopausal women.

“With this comprehensive and up-to-date report the evidence is clear. Having a physically active lifestyle, maintaining a healthy weight throughout life, and limiting alcohol — these are all steps women can take to lower their risk,” McTiernan said in a statement.

The report evaluated 119 studies encompassing data from more than 12 million women, including about 260,000 with breast cancer.

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Put the brakes on booze

Dr. Susan K. Boolbol, chief of the division of breast surgery at Mount Sinai Beth Israel, and associate professor of surgery at Icahn School of Medicine at Mount Sinai, explained that alcohol and breast cancer were already linked.

However, she said, the new report provides more information about exactly how much alcohol can increase the risk.

“This study clearly states that one drink per day will increase your risk. That is major news,” Boolbol told Healthline.

Beer, wine, and spirits all cause an increased risk in both premenopausal and postmenopausal women, McTiernan added.

The AICR recommends no more than one drink per day for women, on average.

Women concerned about their risk might want to substitute alcoholic drinks with low-calorie alternatives like water, sparkling water, tea, or coffee, McTiernan added.

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Workout instead of wine

The premenopausal women who worked out vigorously had a 17 percent lower risk of developing breast cancer compared with those who were the least active, the researchers said.

And postmenopausal women who exercised vigorously had a 10 percent lower risk of developing breast cancer than those who were the least active.

For all women, moderate activity such as gardening or walking, was tied to having a 13 percent lower risk than the women who were least active.

The news of being able to reduce the risk of breast cancer by exercising, along with the warning about drinking, may have some women wondering if a good sweat session is a way to offset a drink.

Boolbol said there is no evidence that working out negates the increased risk of breast cancer from drinking.

McTiernan noted that her data came from various studies, and they were not conducted in the same way, so it’s not possible to know if working out could offset drinking’s effects on breast cancer.

Estrogen is the common mechanism that links alcohol and exercise with breast cancer. High levels of estrogen in the blood have been tied to increased breast cancer risk.

Alcohol may increase estrogens, and exercise may decrease estrogens.

“However, alcohol is a carcinogen by itself, so it’s not clear that you could negate a drink by anything else you do,” McTiernan said.

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Other factors

Being overweight before menopause likely protects women against premenopausal breast cancer — something that Boolbol said she found interesting.

On the flip side, the report found that being overweight or obese through adulthood raises the risk of postmenopausal breast cancer.

“Once again, this study confirmed the fact that postmenopausal weight gain or high BMI is a risk factor for the development of breast cancer,” she said.

McTiernan explained that women make estrogen in their ovaries until menopause, but make it in their fat cells at all ages. More fat cells mean more estrogen, which is known to boost the risk for postmenopausal breast cancer.

The report also confirms that breastfeeding mothers have a lower risk for breast cancer.

Additionally, McTiernan said that some women find protection from a high variety of nonstarchy vegetables, including carrots, spinach, kale, and apricots, which are all high in carotenoids.

“That can also help avoid the common one to two pounds women are gaining every year, which is key for lowering cancer risk,” McTiernan added.

Read more: Cancer survivors aren’t eating as well as they should »

Live healthy

McTiernan advised that women do the following to reduce their risk for breast cancer, and added “it’s never too late to start.”

  • Maintain weight at a normal level.
  • Exercise at least 150 minutes per week at a moderate intensity or greater.
  • Limit alcohol to no more than one drink per day, on average.
  • Eat a plant-based diet high in vegetables and fruits and low in sugars and refined carbohydrates.
  • If you decide to breastfeed your baby, do it for as long as you are able, as it’s good for mothers and babies.

Jasmine McDonald, PhD, an assistant professor of epidemiology at the Columbia University Mailman School of Public Health, agreed.

She noted that the report’s evidence is significant.

“As opposed to genetic susceptibility for breast cancer, alcohol is a modifiable risk factor,” she told Healthline. “Meaning, a woman may not be able to modify her genes, but she can modify her alcohol intake.”