American Journal of Clinical Nutrition, Vol 10, 398-402, Copyright © 1962 by The American Society for Clinical Nutrition, Inc.

Studies of Polyarthritis Induced in Rats by Injection of Mycobacterial Adjuvant

VI. Effects of Dietary Alterations

¹ From the Departments of Medicine and Preventive Medicine, University of California Medical School and the Wadsworth Veterans Hospital, Los Angeles, California

Long-Evans rats were kept for various periods of time on diets adequate in essential nutrients. The experimental diets were either (1) very high in fat, low in carbohydrate and adequate in protein; (2) very high in carbohydrate, very low in fat and adequate in protein; or (3) high in protein, with 50 to 98 per cent of the calories supplied by lactalbumin, as compared with 15 per cent in the control diets.

Female rats were significantly more susceptible to adjuvant arthritis than male rats regardless of the type or duration of the diet.

No significant diet-induced differences were observed in the severity of the arthritis except in comparing control animals with the animals fed 80 or 90 per cent protein. These high protein diets were significantly protective. There was a linear inverse relationship between the percentage of protein in the diet and the severity of the arthritis. Moreover, the longer the diet was fed prior to innoculation with the adjuvant the more marked was the amelioration of the arthritis.

Rats fed the high protein diets did not gain as much weight as did the control rats; whether the protection was due to the protein per se or to a nonspecific effect of diminished weight gain is not known from these experiments.