Reduce Insulin, Reduce Breast Cancer

Insulin levels, thought to influence the risk of breast cancer and other chronic diseases in postmenopausal women, may be regulated by diet and exercise, research published in the Journal of Clinical Oncology suggests.

"Increased physical activity and programs to reduce body mass index (BMI) with both increased physical activity and decreased caloric intake have been proposed to reduce insulin as a potential mediator of breast cancer and other chronic diseases," Rowan Chlebowski (University of California in Los Angeles, Torrance, USA) and co-workers explain.

"However, there are few data on the relative contribution of physical activity, caloric intake, and BMI to fasting insulin levels."

To investigate, the researchers collated information on diet, recreational physical activity, and BMI for 2996 postmenopausal participants in the Women's Health Initiative clinical trials, and assessed their fasting insulin levels.

On average, lower fasting insulin levels were detected in women with a lower BMI, higher levels of physical activity, and lower caloric intake, even after taking into consideration race or ethnicity, age, smoking habits, and alcohol intake.

Specifically, women in the highest quintile for physical activity and lowest quintile for calorie intake had insulin levels of 8.74 µU/ml compared with 15.08 µU/ml in participants classified in the lowest quintile of physical activity and highest caloric intake.

"The results of this study suggest that strategies to reduce BMI and body weight involving either or both increasing physical activity and decreasing caloric intake will reduce insulin levels," Chlebowski's team states.

"These observations support prospective intervention trials incorporating these lifestyle changes to test hypotheses relating insulin to cancer risk."

And the best way to lower body weight, and also keep insulin levels low, is to eat a low-carbohydrate, high-fat diet.

J Clin Oncol 2004; 22: 4507-13

Last updated 18 January 2005