Alcohol may increase the risk of breast cancer because it causes a change in raises estrogen, reduces folate absorption, and causes damage to cell DNA. Alcohol may also increase cancer risk through oxidative stress and impairing how the body eliminates harmful chemicals.

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

In this article, we look at 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.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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According to the National Cancer Institute, there is consistent research that shows an increased risk of breast cancer with increased alcohol consumption.

Data from 118 different 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.

In addition, 2015 research consisting of 88,084 female participants in two cohort studies in the United States, notes that those who had never smoked but were light to moderate drinkers had an increased risk of alcohol-related cancer, particularly breast cancer.

In comparison with females who do not drink any alcohol, research suggests alcohol increases the risk of breast cancer as follows:

  • three alcoholic drinks a week leads to a 15% increased risk
  • an increased risk of 10% for every additional drink people have each day on a regular basis

In females between the ages of 9–15 years, drinking between three and five alcoholic drinks each week triples the risk of developing noncancerous breast lumps. Some types of noncancerous breast lumps may link to an increased risk of breast cancer in later life.

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

Alcohol may increase the risk of breast cancer for the following 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.

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 how much alcohol people consume over time, rather than the type of alcoholic drink, which increases the risk of cancer.

According to the ACS, even consuming small amounts of alcohol may increase the risk of breast cancer in females.

The ACS 2020 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 one drink a day for females and no more than two drinks a day for males.

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

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

Research has shown a consistent link between alcohol consumption and increased risk of breast cancer. This may be due to the effects of alcohol on 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.

Light drinkers have a slight increase in risk, while moderate and heavy drinkers have a higher risk.

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