Interactions between carnosine and vitamin E in mammary cancer risk determination

Carnosine (beta-alanyl-histidine) is found in meats at concentrations as great as 0.35% of wet weight and is an effective antioxidant in in vitro systems though its role in vivo is unclear. Since antioxidant status has been shown to affect risk for carcinogen-induced mammary cancer we conducted a 2x2 factorial experiment assessing the effect of dietary vitamin E (0 or 50 ppm) and carnosine (0 or 875 ppm) on 7,12-dimethylbenz[a]anthracene (DMBA) induced mammary cancer in 55 day old female Sprague-Dawley rats. The diets had no significant effect on body weight gain or organ weight at termination of the experiment 24 weeks following carcinogen administration. As expected, feeding the vitamin E (E) deficient diets resulted in significantly depressed serum and tissue E levels while there was a trend towards increased plasma malondialdehyde levels in E deficiency. Erythrocyte hemolysis was also significantly increased by E deficiency. Carnosine supplementation significantly increased E levels in liver and heart, but not in skeletal muscle, serum, or erythrocytes. Dietary carnosine significantly influenced carnosine. concentrations in liver but not in heart or skeletal muscle; dietary carnosine also significantly elevated histidine concentrations in heart and skeletal muscle but not in serum or in liver. Carnosine supplementation to E deficient rats resulted in a significant increase in tumor latency while non-significantly affecting tumor burden and tumor incidence. Thus, carnosine appears to contribute to the overall antioxidative system, and-its supplementation in the diet affects mammary cancer risk in the DMBA model. (C) 1998 Elsevier Science Inc.