Too Much Protein may Increase Cancer Risk

Ivanhoe Newswire
Thursday, December 7, 2006; 12:00 AM

(Ivanhoe Newswire) -- Eating less protein may help prevent some cancers.

Researchers from Washington University School of Medicine looked at three groups of people -- lean people who ate a low-protein, low-calorie, raw food vegetarian diet, a group of lean endurance runners averaging about 48 miles per week who ate a standard Western diet that had more calories and protein than the first group, and a group of sedentary people who also had the standard Western diet that is higher in sugars, processed refined grains, and animal products.

The low-protein group averaged a daily 0.73 grams of protein per kilogram of body weight, the endurance runners had 1.6 grams, and those in the sedentary group had 1.23 grams. The recommended daily allowance is 0.8 grams of protein.

Results reveal much lower blood levels of plasma insulin-like growth factor 1 (IGF-1) in the low-protein diet group than in the equally lean runners or the sedentary group on the standard Western diet. Previous research has linked high levels of IGF-1 to pre-menopausal breast cancer, prostate cancer, and certain types of colon cancer.

"Our findings show that in normal weight people IGF-1 levels are related to protein intake, independent of body weight and fat mass," reports lead author Luigi Fontana, M.D., Ph.D., Washington University. "I believe our findings suggest that protein intake may be very important in regulating cancer risk."

Fontana adds while the findings suggest connections between protein, IGF-1 levels, and the risk of cancer, more research is needed to clarify the exact connection.

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SOURCE: American Journal of Clinical Nutrition, 2006;84:1456-1462