Researchers studying links between diet and cancer say consumption of large amounts of protein may increase the risk of developing the disease.

Writing in the December issue of the American Journal of Clinical Nutrition, they say consuming a lean diet may be a good way to protect yourself from malignant tumors.

The study focuses on a substance in the body called insulin-like growth factor 1, or IGF-1. This and other hormones have been linked to a higher cancer risk, including premenopausal breast cancer, prostate cancer and certain types of colon cancer. The preliminary results of the study show that people who get a lot of exercise, or who consume a low-protein diet, have lower levels of IGF-1.

Dr. Luigi Fontana, an assistant professor of medicine at Washington University in St. Louis and the lead author of the study, says the presence of a high level of IGF-1 in the body seems to increase the likelihood that there's an elevated risk that mutating cells will turn into cancer cells. It can be controlled to a great degree, he added, through diet.

What's on the good list and what's on the bad list?

No surprises here. Fontana and his fellow researchers suggest a diet that includes fruits and vegetables, along with generous helpings of beans and whole grains. He recommends more fish and less meat high in animal fat.

An added benefit, the study notes, is a diet low in protein is likely to be lower in calories too, making it easier to control your weight. Of course, the reverse is also true, which is one reason Fontana believes consumers in Western nations are battling obesity.