When it comes to breast cancer, the evidence is clear: Zero alcohol is safest. Alcohol is a known cause of female breast cancer. Just one drink a day raises a woman’s lifetime risk by about 4%, and the risk climbs with each additional drink. There’s no safe threshold. It’s a dose-response relationship - the more you drink, the higher the risk. Given that 1 in 8 women will be diagnosed with breast cancer in their lifetime, even a small increase in risk is meaningful. And for women with genetic susceptibility or health factors like obesity, alcohol’s impact can be even greater. Knowing this empowers you to make informed choices about your health—choices grounded in the science instead of wishful thinking or speculation about a “safe” amount.