Alcohol may increase the risk of breast cancer by raising estrogen, reducing folate absorption, and damaging cell DNA. It may also cause oxidative stress and affect how the body eliminates harmful chemicals.

The ethanol in alcoholic drinks may cause an increased risk of breast cancer. Research shows a link between alcohol consumption and breast cancer risk, which increases in relation to how much people drink.

Read on to learn more about the reasons alcohol may increase the risk of breast cancer, how types and amounts of alcohol relate to risk, and whether there is a safe limit to drink.

The use of binary terms such as “male” and “female” or “men” and “women” in this article reflects the language of the sources we’ve used. Unless otherwise noted, it’s unclear whether the research we reference included participants with expansive gender identities.

According to the National Cancer Institute, some research shows an increased risk of breast cancer with increased alcohol consumption.

Data from studies suggests that light drinkers have a slight increase in breast cancer risk compared with those who do not drink alcohol. Moderate drinkers and heavy drinkers have a higher risk.

The World Health Organization (WHO) suggests that drinking alcohol is one of the biggest risk factors for breast cancer. Specifically, alcohol is responsible for 7 in 100 new breast cancer cases in the WHO European Region.

Alcohol may increase the risk of breast cancer for numerous reasons.

Decreased folate

Low folate levels may have a link to an increased risk of breast cancer.

Alcohol may reduce how well the body absorbs certain nutrients, including folate. Folate is an important vitamin for keeping cells healthy. Heavy drinkers may have particularly low absorption of nutrients and low folate levels.

Hormone levels

Estrogen is a hormone that plays an important role in breast tissue growth and development. Higher estrogen levels may increase the risk of breast cancer. Alcohol can raise estrogen levels.

Alcohol may also increase other hormones that have a link to hormone receptor-positive breast cancer.

DNA damage

Alcohol may cause damage to DNA in cells, which can increase the risk of breast cancer. Alcohol can convert to a chemical called acetaldehyde, which can damage cell DNA.

Alcohol can also cause oxidative stress, which can cause cell damage and increase cancer risk.

Other effects

Alcohol can slow down how well the body is able to get rid of harmful chemicals, such as substances in tobacco smoke. It also increases how easily these chemicals enter cells in the lining of the upper section of the digestive tract.

In addition, consuming alcohol can increase calorie intake, which may be a factor in developing obesity. This can increase breast cancer risk.

According to BreastCancer.org, the absolute risk of breast cancer in women who drank less than one drink per week is 11.3%. This compares with an absolute risk of 15.3% in those who drink two drinks per day.

Those who drank around 1 drink per day had an increased risk of about 10% compared with those who do not drink alcohol.

Although there is little research on alcohol and recurrence, a systematic review from 2016 points out that consuming alcohol may increase the chance of breast cancer recurrence, particularly in those who are postmenopausal.

Alcoholic drinks, including beer, wine, and liquor, contain ethanol. According to the American Cancer Society (ACS), it is the ethanol in alcohol that likely increases the risk of cancer, rather than any other ingredients in alcoholic drinks.

Ethanol amounts can vary in different alcoholic drinks, but the following standard-size drinks usually contain around half an ounce (oz) of ethanol:

  • 12 oz beer
  • 5 oz wine
  • 1.5 oz of 80-proof liquor

Larger quantities, or stronger drinks, will contain higher levels of ethanol.

It is likely that how much alcohol people consume over time, rather than the type of alcoholic drink, increases the risk of cancer.

According to the ACS, even consuming small amounts of alcohol may increase the risk of breast cancer in women. The ACS also states that alcohol accounts for about 5% of all cancers.

The ACS Diet and Physical Activity Guideline for cancer prevention notes that it is best to avoid drinking alcohol.

However, if people choose to drink alcohol, the guideline suggests no more than 1 drink a day for women and no more than 2 drinks a day for men.

The National Institute on Alcohol Abuse and Alcoholism states that the recommended alcohol limit is lower for women due to a smaller average body size than men.

In addition, women typically have less water in their bodies. As the body stores alcohol mostly in body water, the blood-alcohol concentration would be higher for women despite them drinking the same amount of alcohol.

Research has shown a link between alcohol consumption and increased risk of breast cancer. This may be due to the effects of alcohol on the absorption of folate, increasing estrogen and other hormone levels, and DNA damage in cells.

Alcohol may also impair the body’s ability to eliminate harmful chemicals, and excess calorie intake from alcohol may lead to weight gain, which may also be a risk factor.

Avoiding or limiting alcohol intake may be an important factor in helping to reduce the risk of breast cancer.