Nutrition and Resistance to Infection

Abstract

Summary The influence of various forms of nutritional deficiency on the bactericidal and phagocytic properties of the peritoneal fluid has been studied in rats following an injection of Salmonella typhi murium. Deficiency of either thiamin, riboflavin or vitamin A leads to a lowering of the bactericidal power. The deficient rat organism, deprived of humoral antibodies, counters the bacterial invasion by mobilising its phagocytic apparatus. Prolonged moderate or sudden severe restriction of food intake leads to a lowering of bactericidal power and to an increase of the phagocytic activity. The reduction of bactericidal power of peritoneal fluid in rats restricted as to food intake is due largely to caloric deficiency. Protein restriction exerts a similar but less marked effect. Protein supplementation of a low-calorie diet does not alleviate the deleterious effect of caloric deficiency. It is concluded that diminished resistance to Salmonella infection in rats kept on diets deficient either in vitamins, calories or protein is due to impairment of the humoral antibody response rather than to a diminution of phagocytic activity.