LONDON — Greenbrook added that there wasn't yet enough proof about the dangers of red meat to change current prevention guidelines.
Others said diet is notoriously difficult to measure, and that the link between eating red meat and breast cancer appeared weak. Valerie Beral, a cancer expert at the University of Oxford, pointed out that vegetarians don't have a lower risk of breast cancer than meat-eaters.
Still, Mia Gaudet, director of genetic epidemiology at the American Cancer Society, said it was plausible that red meat could somehow be connected to breast cancer and that women's eating habits in their 20s might be particularly significant.
"Breasts are still developing and are more susceptible to carcinogens before women have their first full-term pregnancy," she said.
Gaudet, who doesn't eat red meat herself, said the American Cancer Society recommends people eat a "plant-based" diet.
"It's important to have a healthy lifestyle throughout your life and not just as you get older and more worried about cancer," she said. "People should perhaps consider ordering a salad or a vegetarian option sometime."