Could the amount of food energy you take in each day help determine your odds for developing cancer? It's a hypothesis that's been gaining traction in recent years, with numerous studies in animals suggesting that long-term caloric restriction might ward off a number of illnesses and significantly extend the lifespan.
Now, part of a major project funded by the U.S. National Cancer Institute will seek to discover whether reducing daily caloric intake can reduce the risk for cancer in humans. As described July 14 in the NCI Cancer Bulletin, the $54 million, 5-year Transdisciplinary Research on Energetics and Cancer (TREC) initiative is a collaboration between nutritionists, molecular biologists, epidemiologists and others, focused on the diet-exercise-cancer nexus.
Caloric restriction "is the most potent broadly acting dietary intervention we know of that actually prevents cancer in experimental models," Dr. Stephen Hursting, former deputy director of the NCI's Division of Cancer Prevention and now chair of the Department of Nutritional Sciences at the University of Texas, told the Bulletin.
As part of the TREC initiative, Drs. Cornelia Ulrich and Anne McTiernan of the Fred Hutchinson Cancer Research Center, Seattle, are looking at whether women who undergo months of caloric restriction show alterations in certain cancer-linked markers in the blood. Women in the diet arms of the study will be asked to consume between 1,200 to 1,500 calories per day-well below the typical 1,700 to 1,800 daily calories per day consumed by older women in the general population, as noted in a recent CDC survey.
The goal is to have women in the caloric-restriction cohort lose 10 percent of their weight within the first 6 months of the study, and then use blood samples to check for changes in markers of DNA damage and lymphocyte repair, as well as markers of inflammation such as interleukin 6, serum amyloid A and C-reactive protein.
The above markers have been linked to increased cancer risk and poorer prognosis after a cancer diagnosis. "We want to know whether health benefits for cancer can be achieved if women exercise regularly, even if they do not lose much weight or, alternatively, if weight loss is essential, which is achieved more easily through caloric restriction," Dr. Ulrich told the Bulletin. "We can also figure out whether body fat loss or other changes in body composition are critical to reduce risk factors for cancer, or whether an increase in fitness is equally important."
A prior study did find vigorous exercise to be linked to a decrease in C-reactive protein, while more sedentary participants showed a rise in the inflammatory marker.
The NCI-funded team should have more answers soon: the first results from the Seattle-based TREC trial are due to be reported early in 2010.
