LIPID-ACCUMULATION IN OBESE ZUCKER RATS IS REDUCED BY INCLUSION OF RAW KIDNEY BEAN (PHASEOLUS-VULGARIS) IN THE DIET

The effects of inclusion of different levels of raw kidney bean (Phase olus vulgaris) of high lectin content (27 g/kg meal) in a high-quality (lactalbumin) control diet were tested in nutritional trials on the g rowth and metabolism of obese Zucker (fafa) rats and their lean litter mates in comparison with pair-fed controls. All diets contained 100 g total protein/kg and either 50 g lipids/kg (low fat) or 150 g lipids/k g (moderate fat). The growth of both obese and lean rats on bean diets was retarded by the daily bean intake in a dose-dependent manner. How ever, most of this was because bean-fed rats contained less body fat t han the controls after 10 d. Thus, after feeding low-fat diets contain ing up to 130 g kidney bean/kg (lectin intake less than or equal to 0. 2 g/kg body weight (BW) per d) in both 10 d and 70 d trials, the bodie s of obese rats contained less fat but not protein than their pair-fed controls. Moreover, by increasing the Lipid content of the diet to 15 0 g/kg, the level of bean inclusion could be increased to 280 g/kg (le ctin intake greater than or equal to 0.4 g/kg BW per d) without loss o f body protein and skeletal muscle. Although these rats contained more body fat than those which were fed on low-fat diets, their weight red uction could be accounted for exclusively by reduced lipid content. In contrast, significant body protein loss occurred when the same diet o f high lectin content was fed to lean Littermates. Plasma insulin leve ls were significantly depressed in the obese Zucker rats on bean diets but the pancreas was not significantly enlarged nor its insulin conte nt changed in 10 d trials. However, significant pancreatic growth occu rred on long-term (70 d) bean feeding compared with pair-fed controls. The results suggest that, in addition to animal nutrition, it may als o be possible to use the bean lectin as a dietary adjunct or therapeut ic agent to stimulate gut function and ameliorate obesity if a safe an d effective dose-range can be established for human subjects.