Effect of feeding a raw winged bean seeds on gastrointestinal functions in rats

The primary cause of the adverse effects of feeding of raw winged bean seeds in rats was investigated. In experiment 1, rats were fed on either a raw winged bean diet or a steamed winged bean diet for 10 days. Body weight gain of rats fed on 30% raw winged bean diet was significantly lower than that of rats fed on 30% steamed winged bean diet. The adverse effect of the feeding of 30% raw winged bean diet on growth was accompanied by disorders of the gastrointestinal tract including a significant reduction in intestinal sucrase activity, not being improved with feeding of the diet supplemented with methionine. In experiment 2, rats fasted for 2 days were refed on a 10% casein diet, a 30% raw winged bean diet or a 30% steamed winged bean diet, in which most of the carbohydrate component was sucrose, for 4 days. Although body weight gain and food consumption in rats refed on these winged bean diets were lower than those in rats refed on 10% casein diet, the effects of feeding of the raw winged bean diet on body weight gain and food consumption were extremely deleterious as compared with those of feeding of the steamed winged bean diet. Significant reductions in hydrolase activities localized in the brush border membrane of the small intestine were found in rats refed on the raw winged bean diet prior to the occurrence of apparent disorders in the gastrointestinal tract. These findings suggest that the primary cause of the adverse effects of raw winged bean seed feeding the disorders in the small intestine caused by lectin or similar substances in raw winged bean seeds.