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

Abstract

SummaryThe 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 carbohyd rate 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 is disorders in the small intestine caused by lectin or similar substances in raw winged bean seeds. Key Words winged bean, lectin, small intestine, sucrase, alkaline phos phatase, leucine aminopeptidaseThe winged bean (Psophocarpus tetragonolobus) seems to be a crop with nutritional potential (1, 2). Protein, lipid, mineral and vitamin components of winged bean seeds were similar to those of soybean The diets prepared with the ground raw seeds were toxic to rats, and the activity of trypsin inhibitor, amylase 27

Oral toxicity of Kintoki bean (Phaseolus vulgaris) lectin.

“…As presumed from our previous data (13,14) and other investigators' data (4,18,19) indicating the presence of antinutritive factors in raw beans, whole Kintoki bean when orally ingested was proved to have a toxic effect on mice and rats. Mice fed a diet containing autoclaved Kintoki bean at a 10% protein level increased their body weight 10% in nine days, and their motion was also normal in experiment 1.…”

“…However, such an in hibition of nutrient absorption is brought about by not only the physical disruption in the intestinal tissue but other reasons. For example, it has been reported that the winged bean diet lowered the intraluminal sucrase activity (18), and that raw field bean diet accelerated the guanidinoacetate methyltransferase activity and thereby the protein catabolism in the liver (22). The binding of the intrinsic factor-vitamin B12 complex to brush border membranes is also reported to be interfered by a lectin (23).…”

The effect of lectin from taro tuber (Colocasia antiquorum) given by force-feeding on the growth of mice.

“…It was reported that a winged bean diet lowered intestinal sucrase activity and a raw field bean diet accelerated guanidinoacetate methyltransferase activity and thereby the protein catabolism in the liver (21,22). Deren et al reported that the activities of intestinal sucrase and LAPse in rats responded to variation in dietary contents (23).…”

Effect of ingested winged bean lectin on gastrointestinal function in the rat.

“…Jaffe and Korte (4) reported that trypsin inhibitor, amylase inhibitor and lectins are present in raw winged beans (Psophocarpus tetragonolobus) and that diets prepared with the raw beans are toxic to rats. In our previous study (5), the lectins or similar substances present in raw winged beans were suggested to be major factors in the toxicity.…”