Alice Bender, head of nutrition programs at AICR, explained in the study that alcohol is a known carcinogen that can damage DNA and boost estrogen, which can raise the risk of cancer in people of all ages.
Anne McTiernan, a cancer prevention expert at the Fred Hutchinson Cancer Research Center and the study's lead author, said she was surprised by the outcome of the research.
"Some other individual studies had suggested that risk only started with 2 drinks per day or more," She said.
"But this meta-analysis, where we combined results from many large cohort studies, was definitive."
Vigorous activity further lowers breast cancer risk compared to moderate exercise, according to the study. Meanwhile, unhealthy weight increases the risk for many cancers, because certain types of body fats release dangerous hormones and compounds.
"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, noting that following these guidelines do not guarantee that you will avoid breast cancer but can rather be compared to wearing a seatbelt.
"It's not a surety that you'll be saved from injury in a car crash, but using a seat belt reduces your risk."
