Half a glass of wine would raise breast cancer risk in women, warn doctors.
Professor Sir Ian Gilmore said that even those who stick within Government recommended limits for alcohol could be at higher risk.
He warned that one unit of alcohol a day - half a glass of wine - increased the risk of breast cancer by 10 percent.
Gilmore, who had been addressing MPs at the health select committee, said that it was important that this information "was in the public domain".
"There is no safe limit for all conditions," the Daily Mail quoted him as saying.
"But the risk of breast cancer increases even for women who stick within the safe limits," he added.
Gilmore, former head of the Royal College of Physicians, was referring to a major ongoing study carried out by Oxford University involving more than a million women.