Comparison of the effect of dietary casein and cottonseed protein on food intake and growth in normal and tumorbearing rats

Abstract

Male Fischer 344 rats with (tumor-bearers) and without (controls) a transplantable methylcholanthrene sarcoma were fed isonitrogenous, isoenergetic diets containing either casein or cottonseed protein (CSP) so as to compare the effects of these two proteins on the development of cancer-induced anorexia and cachexia. For both diets, tumor growth was associated with depressed food intake, decreased body weight, hypoalbuminemia and hyperlipidemia. Diet had no effect on food intake, weight gain or serum albumin for either controls or tumor-bearers; tumor weight was unaffected by type of dietary protein. Liver weights were lower for animals fed CSP than for those fed casein. Dietary CSP exerted a hypolipidemic effect in normal rats, but this differential effect of protein quality on serum lipids was abolished by tumor growth, as were differences in serum fatty acid profile associated with consumption of CSP. Tumor growth itself was associated with altered fatty acid profiles in serum, with the percentages of fatty acids as stearic and arachidonic acids being decreased and the percentages as oleic and linoleic acids being increased. Thus, dietary CSP has similar effects to casein on the development of cancer anorexia and cachexia in this animal model. The effects of protein quality on serum lipids, however, can be altered by tumor growth.