Understanding pathways of calorie restriction: a way to prevent cancer?

F or decades, researchers have been intrigued by calorie restriction, a tried and true way of extending lifespans in creatures ranging from yeast and roundworms to flies and mice. Aside from increasing the lifespan of organisms up to 80% in some studies, calorie restriction (with proper nutrition) also leads to lower insulin, glucose, and blood pressure levels, as well as increased white blood cell count. Particularly enticing is the possibility for caloric restriction to prevent, delay, and shrink a variety of tumors, a fi nding that seems to complement those of recent studies linking obesity and cancer. In animal studies, researchers reduce food intake by 10% – 60%, but because such extreme dieting would be unrealistic in humans, many researchers are now examining the biological pathways affected by caloric restriction with the aim of developing preventive agents for cancer as well as other diseases associated with aging. Together with the growing fi eld of calorie restriction mimetics — fi nding natural or synthetic compounds that mimic the effects of caloric restriction — they are fi nding these pathways to be numerous and complex. “The fi eld of [caloric restriction] seems to grow every day with new discoveries of genes, pathways, and proteins that are affected in different ways,” Julie Mattison, Ph.D., a caloric restriction researcher at the National Institute on Aging (NIA), wrote in an e-mail. In gaining information about the systems changed by caloric restriction, she said, researchers can identify targets for mimetics.