Researchers have been looking for a dietary link to breast cancer for decades. The high-fat hypothesis from years ago is not supported by evidence. But researchers with the European Prospective Investigation into Cancer and Nutrition have identified danger with a high-carb diet. The study included almost 335,000 women. Over the course of twelve years, almost 12,000 of them developed breast cancer.
Postmenopausal women were significantly more likely to develop dangerous estrogen receptor-negative tumors if they ate a diet full of foods that make blood sugar and insulin spike. Processed carbohydrates such as cookies, crackers, and white bread typically cause this metabolic reaction. Avoiding a high glycemic load diet is considered helpful in reducing the risk of diabetes and heart disease. Now women have one more good reason to focus on lean protein and vegetables and skip starches and sugars.
[American Journal of Clinical Nutrition, August, 2012]