Nutritional response of mature rats to kidney bean (<i>Phaseolus vulgaris</i>) lectins

Abstract

Abstract In a series of 10‐day pair feeding experiments it was found that the nutritional value of diets containing beans was essentially the same for rats aged between 30 and 123 days. Thus net protein utilisation (NPU) values of 25–39 on diets containing Processor bean (35 g protein kg −1 ) + egg albumin (65g protein kg −1 ) were obtained. As food intakes were considerably reduced when rats were fed diets containing more than 35g protein kg −1 of Processor bean, the measurement of protein utilisation became increasingly more difficult. The severe disruption of the brush borders of duodenal and jejunal enterocytes, originally observed when bean‐containing diets were fed to young (30‐day‐old) rats was also found with rats up to the age of 120 days on similar diets. Similarly, the development of circulating anti‐lectin antibodies in the animals showed no age dependence within the age limits investigated. It was also shown that oral immunisation did not protect the rats from the effects of toxicity and that the immune response was a result of continuous absorption of lectin throughout the feeding period. Thus the extent and the mechanism of toxicity of Phaseolus vulgaris bean lectins were found not to be dependent on the age or maturity of the animal.