Cancer
Calorie restriction helps fight cancer
By David Liu, Ph. D.
Apr 14, 2008 - 1:03:18 PM

Caption: John DiGiovanni, Ph.D., director of the Department of Carcinogenesis and of M.D. Anderson's Science Park - Research Division in Smithville, Texas. Credit: M. D. Anderson Cancer Center

MONDAY April 14, 2008 (Foodconsumer.org) – Eating fewer calories than needed or calorie restriction may help reduce risk of a variety of cancers, according to a new study presented today at the American Association for Cancer Research annual meeting.

Many studies have linked specific foods with the risk of all types of cancer.  Epidemiologic and laboratory studies suggested that calorie intake may play a role in the development of a variety of cancers.

The current study showed a restricted-calorie diet inhibited the development of precancerous growths in a two step model of skin cancer.

Calorie restriction reduced the activation of two signaling pathways known to contribute to cancer growth and development while an obesity-induced diet activated those pathways, the study showed.

Researchers at The University of Texas M. D. Anderson Cancer Center conducted the study.

"These results, while tested in a mouse model of skin cancer, are broadly applicable to epithelial cancers in other tissues," said senior author John DiGiovanni, director of the Department of Carcinogenesis and of M.D. Anderson's Science Park - Research Division in Smithville, Texas.

Epithelial cancers arise in the epithelium - the tissue that lines the surfaces and cavities of the body's organs.  The study results suggested that calorie restriction may help fight epithelial cancers or 80 percent of all cancers.

"Calorie restriction and obesity directly affect activation of the cell surface receptors epidermal growth factor (EGFR) and insulin-like growth factor (IGF-1R)," Moore said. "These receptors then affect signaling in downstream molecular pathways such as Akt and mTOR."

"Calorie restriction, which we refer to as negative energy balance, inhibits this signaling, and obesity, or positive energy balance, enhances signaling through these pathways, leading to cell growth, proliferation and survival," Moore said.

Both experimental and epidemiological have suggested that eating more calories than needed for a long period, which can lead to obesity, increases the risk of developing a variety of cancers while eating fewer calories than needed often decreases the risk, DiGiovanni said.

In the mice that were exposed to an agent to induce pre-malignant lesions called papillomas, the researchers tested four diets, two with calorie reductions of 30 percent and 15 percent, a control diet with 10 percent kilocalories from fat, and an obesity-inducing diet with 60 percent kilocalories from fat.

Those on the calorie-restricted diets developed significantly fewer papillomas than those on other two diets.  However, further experiments demonstrated that calorie restriction did not affect the progression of the existing papilomas to carcinomas.