It still isn’t clear that what we eat as adults will impact our risk for cancer. But there is lots of evidence that what girls eat—especially during puberty—can affect their risk of getting breast cancer in adulthood. The theory is that certain compounds in food impact breast tissue as that tissue is developing, either conferring lifelong protection against cancer or raising risk for cancer.

I wrote several months ago about soyfood consumption during the teen years and how it can protect against breast cancer in adulthood. More recently, Harvard researchers looked at the effect of red meat consumption during adolescence. They asked more than 40,000 women what they ate in high school, and then followed their health over the next seven years. Those who reported eating the most red meat and processed meat during their teen years had a more than 30% higher risk for getting breast cancer as adults.

What is most interesting is that changing eating habits for the better later in life may not confer that much protection. The evidence tells us that the time when breast tissue develops is the crucial time for raising or lowering risk.

So do your daughters a favor: Replace the hamburgers in their diets with veggie burgers and pour them a glass of fortified soymilk. Their lifelong health may depend on it.