CR May Provide Some Protection Against Intestinal Cancer, Based On Animal Studies
Following are excerpts and references from animal studies of the effects of CR on colon cancer. In all cases the original paper should be read for a full understanding of what was being studied and what could be concluded.
Human Studies (None Available)
Animal Studies - Primate
Title: "Caloric Restriction Delays Disease Onset and Mortality in Rhesus Monkeys"
Ricki J. Colman, Rozalyn M. Anderson, Sterling C. Johnson, Erik K. Kastman,
Kristopher J. Kosmatka, T. Mark Beasley, David B. Allison, Christina Cruzen,
Heather A. Simmons, Joseph W. Kemnitz, and Richard Weindruch
Science 10 July 2009: 201-204
"The incidence of cancer increases with age in rhesus monkeys, and intestinal
adenocarcinoma is the most commonly diagnosed cancer in these animals (14).
The methods used to detect and determine the type of cancer are described
(7). The incidence of neoplasia was reduced by 50% in the animals undergoing
CR as compared to that in controls (Fig. 3A). The most common form of
neoplasia was gastrointestinal adenocarcinoma, which was identified in seven
of the eight cases in the control animals and in two of the four cases in
the animals on CR."
Animal Studies - Non-primate
Title: "Effect of different levels of calorie restriction on azoxymethane-induced colon carcinogenesis in male F344 rats"
Cancer Research, Vol 50, Issue 18 5761-5766.; SP Kumar, SJ Roy, K Tokumo and BS Reddy
"Epidemiological and animal model studies indicate that increased calorie intake increases the risk for colon cancer development. Previous studies in animal models restricted the calorie intake severely, and none of these studies have investigated a dose-response effect of different levels of calorie restriction on colon carcinogenesis. The present study was designed to investigate the effect of various levels of calorie restriction on colon carcinogenesis in male F344 rats fed the low and high fat diets and the effect of these diets on the activities of colonic mucosal and tumor ornithine decarboxylase (ODC) and protein tyrosine kinase...."
"The regression coefficient representing the dose-response effect of different levels of calorie restriction in both high fat groups is significant. Results also indicate that AOM [azoxymethane] treatment significantly increased the colonic mucosal ODC and protein tyrosine kinase activities. This stimulation was inhibited by feeding the calorie-restricted diets. ODC and protein tyrosine kinase activities were lower in the colon tumors of animals fed the calorie-restricted diets. "
Title: "Energy restriction reduces the number of advanced aberrant crypt foci and attenuates the expression of colonic transforming growth factor beta and cyclooxygenase isoforms in Zucker obese (fa/fa) rats."
Cancer Research. 63(20):6595-601, 2003 Oct 15.; Raju, Jayadev. Bird, Ranjana P.
"Several epidemiological studies have supported the concept that high energy intake, obesity, and/or hyperinsulinemia are risk factors for colon cancer. Previously, it was shown that Zucker obese rats are more sensitive to chemically induced colon cancer than their lean counterparts. The present study investigated whether moderate (20-25%) dietary energy restriction (ER) would attenuate colon carcinogenesis in the Zucker obese rat model..."
"This study is the first to demonstrate that moderate ER attenuated TGF-beta and COX protein expression and the carcinogenic process in Zucker obese rats. These findings provide insights leading to the proposal that the mechanism(s) underlying the early events of colon carcinogenesis in Zucker obese rats may extend beyond the role of excessive body weight and hyperinsulinemia per se.