High-Carb Diet Linked to Breast Cancer

(WebMD.com) - Eating a diet high in carbohydrates -- particularly the sugary kinds -- may be linked to an increased risk of breast cancer in women.

But don't jump to conclusions, says Walter Willet, MD, MPH, DrPH, of the Harvard School of Public Health, who studied the topic with researchers at the Instituto de Salud Publica in Cuernavaca, Mexico, Brigham and Women's Hospital in Boston, and Harvard Medical School.

"One study is not enough to make major changes in diet, and more work on this topic is urgently needed," says Willet in a news release.

The urgency stems from a study of 1,866 women aged 20 to 75 in Mexico City. Researchers interviewed the women about their diets and found that breast cancer risk rose with carbohydrate consumption. Those who ate the most carbohydrates had more than twice the risk of breast cancer than those who at the least. The increased risk of breast cancer was seen both in premenopausal and postmenopausal women.

The results held after other risk factors like body mass index (a measure of body fat), family history of breast cancer, and the age at which the women first gave birth were screened out.

Insulin's Role

Researchers say the reason high carbohydrate consumption may be linked to breast cancer may stem from elevated levels of insulin and insulin-like proteins in the women's blood. Recent studies have shown that these can increase the level of the female hormone estrogen, which is associated with breast cancer.

All carbohydrates are not alike. In this study, one kind particularly stood out -- sucrose, or table sugar. "Sucrose intake was significantly related to the risk of breast cancer," write the researchers.

Sugary foods spike blood sugar levels, triggering high insulin levels and a process that could ultimately make cells grow. Insulin and a similar protein called insulin-like growth factor (IGF) may also boost levels of estrogen.

The study linked insoluble fiber -- the kind that can't be digested -- with lower risk of breast cancer.

The study failed to show an association between dietary fat and overall breast cancer risk.

Read more...