Inhibitory effect of L-arginine on growth of rat mammary tumors induced by 7,12-dimethylbenz(a)anthracene.

The effect of L-arginine on growth of rat mammary tumors induced by 7,12-dimethylbenz(a)anthracene was studied. Growth of induced tumors was inhibited by feeding rats an arginine-enriched diet containing 5% L-arginine in addition to the necessary components for rats, including 15% milk casein. The diet significantly reduced both the rate of tumor induction and the number of tumors induced per rat. Histological examination showed that the tumors induced were more benign in rats fed the arginine-enriched diet than in those fed the control diet. A possible mechanism of the inhibitory effect of L-agrinine id discussed.