Interactions between carnosine and vitamin E in mammary cancer risk determination

Carnosine (B-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-dimethytbenz[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.