The effect of certain diets on hepatic tumor formation due to m-methyl-p-dimethylaminoazobenzene and o'methyl-p-dimethylaminoazobenzene.

It has repeatedly been demonstrated that the nature of the diet can influence the rate at which hepatic tumors develop in rats fed p-dimethylaminoazobenzene. Dietary factors that retard the formation of such tumors include riboflavin (6, 14), hydrogenated coconut oil (10, 11) and several others. Dietary factors that accelerate tumor formation under these conditions include the crude mixture of extractives in commercial concentrate of rice bran (13, 14). The evidence has been summarized in a recent review (17). While the experiments themselves are reproducible, the significance of these dietary effects on carcinogenesis is still open to question. Thus it has been pointed out (13, 17) that tumors of most other organs, whether spontaneous or induced by agents such as carcinogenic hydrocarbons or ultraviolet light, are not nearly so sensitive to diet as liver tumors due to p-dimethylaminoazobenzene, and hence one may ask whether the dietary factors are concerned with the fundamental carcinogenic reaction, or whether they act primarily by destroying or preserving the azo dye used as a carcinogen. One experimental approach to this question would be to determine the effect of diet on the induction of hepatic tumors by agents other than p-dimethylaminoazobenzene. For if the carcinogenic reaction were involved, a similar response to diet might be expected of all carcinogens for that organ. On the other hand, if diet merely alters the rate at which carcinogenic chemicals are destroyed in the body, different responses to diet could result when different carcinogens are used, although a similarity in response is also possible if the same chemical grouping as, for example, the azo link-