Impact of dietary protein and fat source on the development of insulin-dependent diabetes in the BB rat.

Epidemiological studies show a remarkable geographical difference in the prevalence of IDDM, suggesting a role for environmental factors such as diet, infection, or stress in the etiology of the disease. Dietary modification has already been shown to be effective in the prevention of autoimmune diabetes in the BB rat and NOD mouse. We studied the effect of protein and fat source in the prophylaxis of diabetes in the BB rat. Natural ingredient rat chow was consistently associated with a high expression of the disease, whereas a casein-based, defined diet significantly inhibited the development of diabetes. Substitution of casein with raw red lentils resulted in a markedly higher incidence. This is the first highly diabetogenic defined diet in the BB rat. Neither fish oil nor soy oil enhanced diabetes expression in the BB rat. Increased amounts of soy oil also did not influence the disease process. These results suggest a central role for dietary protein source in the pathogenesis of BB rat diabetes. We speculate that plant proteins containing anti-nutrients such as chemicals, lectins, enzyme inhibitors, and nonphysiologic amino acids may initiate or hasten the pathogenesis process via beta cell stress or immune response activation.