Inhibition of dmba‐induced mammary tumorigenesis by caloric restriction in rats fed high‐fat diets

Abstract

Most previous studies on the inhibiting effect of caloric restriction during promotion of DMBA-induced mammary carcinogenesis have used low to moderate levels of dietary fat, i.e., about 4 to 14% by weight. The current study was designed to test whether a moderate degree of caloric restriction, 25%, would inhibit tumor growth in rats fed the equivalent of 20% dietary fat which approximates human consumption in affluent countries. Rats were fed diets ad libitum that contained 5, 15 or 20% corn oil. Groups of rats were pair-fed to the last 2 groups, but subjected to a 25% caloric restriction. These groups were fed 20 or 26.7% corn oil so that absolute fat intake in the paired groups was identical. Significant inhibition of tumor incidence, tumor weight, tumor burden, body fat deposition, and fasting serum insulin were observed in the 2 calorically restricted groups. We conclude that moderate caloric restriction is significantly more effective in inhibiting tumor growth than is the promoting effect of diets high in fat. Total body weight, body fat and serum insulin concentrations may be better correlates of risk of developing mammary tumors than is dietary fat.

Height, weight, weight change and risk of breast cancer in Rio de Janeiro, Brazil

“…14,15 Results of studies on laboratory animals support the hypothesis that early energy restriction may decelerate height, delaying the onset of sexual maturation, and reducing the oncogene expression and tumor growth. 4,33,34 The lack of association between height and breast cancer in this study may be due to the fact that the Brazilian population is still shorter than the population in developed countries even with the increasing height that has been shown in Brazilian National Surveys. 28,29 The fourth quartile value for height, for both pre and postmenopausal women in our study, is very close to the reference category in three prospective studies carried out in developed countries.…”

Calorie restriction: Decelerating mTOR-driven aging from cells to organisms (including humans)

“…For example, CR prevents cancer in rodents. [9][10][11][12][13][14] In humans, weight loss is recommended for both prevention and therapy of all age-related diseases from atherosclerosis to osteoporosis. As we will discuss, there is overwhelming evidence that "eating as much as you wish" (known as ad libitum in animals) accelerates all age-related diseases, dramatically shortening human life span.…”

Dietary factors, hormesis and health

“…For example, mortality from natural causes or that caused by thermal and oxidative stress exposures to specific toxins is significantly reduced in animals that have been maintained on DER compared to control animals consuming a normal diet (Fernandes et al, 1976;Hall et al, 2000;Vasselli et al, 2005;Lee et al, 2006). DER protects rodents against cancers induced in a wide range of tissues and by many different carcinogens including pancreatic tumors induced by azaserine (Roebuck et al, 1981), mammary tumors induced by DMBA (Klurfeld et al, 1989) and prostate cancer induced by N-methyl-N-nitrosourea and testosterone (Boileau et al, 2003). DER was effective in protecting heart and brain cells against ischemic injury in models of myocardial infarction and stroke (Yu and Mattson,1999;Ahmet et al, 2005).…”