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Title: MODULATION OF CARBOHYDRATE METABOLISM AND PEPTIDE HORMONES BY SOYBEAN ISOFLAVONES AND PROBIOTICS IN OBESITY AND DIABETES

Author
item ALI, ALI - PL:BHNRC,BELTSVILLE,MD
item VELASQUEZ, MANUEL - GW UNIV, WASHINGTON,DC
item HANSEN, CARL - NIH, BETHESDA,MD
item MOHAMED, ALI - VA ST UNIV, PETERSBURG
item BHATHENA, SAM - PL:BHNRC,BELTSVILLE,MD

Submitted to: Journal of Nutritional Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2005
Publication Date: N/A
Citation: N/A

Interpretive Summary: We and others have shown that soybean have beneficial effects on carbohydrate and lipid metabolism in many nutritional disorders such as obesity, diabetes, cardiovascular disease and certain forms of cancer. Carbohydrate and lipid metabolism are influenced by peptide hormones. The beneficial effect could be due to the presence of isoflavones (phytoestrogens). We therefore investigated the effect of soybean isoflavones on glucose and triglyceride metabolism and peptide hormones in an animal model of obesity and diabetes. Probiotics may convert inactive isoflavones glycosides to the active form aglycones, thereby potentiating the effect of isoflavones on glucose and triglyceride metabolism. We fed lean and obese SHR/N-cp rats with casein and 0.1% isoflavone, 0.1% probiotics or both together. We observed that isoflavones given alone lowered plasma glucose in lean and obese rats but lowered triglyceride in only lean rats. Isoflavones also had significant effect on plasma insulin, leptin and glucagon in lean rats but not in obese rats. Thus our data show that in lean animals isoflavones have beneficial effect on glucose and triglyceride metabolism and the effect is due to changes in hormones involved in their metabolism. Isoflavones have no significant effect when levels of triglycerides are very high as in obese rats. Our data also show that probiotics do not potentiate the effect of isoflavones. These data will help nutritionists, dietitians and medical professionals in recommending the type of protein which contain isoflavones, for proper nutrition of the general population, to medical professionals involved in the treatment of obese subjects and those with diabetes, and also to the food processing industry.

Technical Abstract: Soybean and its isoflavones have been shown to have beneficial effects on carbohydrate and lipid metabolism and on renal function. Probiotics may potentiate the beneficial effects of isoflavones by converting the inactive isoflavone glycoside to aglycones which are biologically active thereby producing a synergistic effect. We therefore studied the effects of soybean isoflavones in the presence and absence of probiotics on glucose and triglyceride metabolism and the peptide hormones involved in their metabolism. Lean and obese SHR/N-cp rats were fed AIN 93 diets containing either 0.1% soybean isoflavone mixture, 0.1% probiotics mixture or the both together. Plasma was analyzed for glucose, triglycerides, parameters of renal function and peptide hormones - insulin, leptin, glucagon and ACTH - that are involved in glucose and lipid metabolism. Isoflavones given alone lowered plasma glucose in both phenotypes while triglyceride was decreased only in lean animals. Isoflavones also lowered AST and ALT in both phenotypes. Isoflavones had significant effect on plasma insulin, leptin and glucagon in lean rats but not in obese rats. Thus, our data show that in lean animals isoflavones have hypoglycemic and hypolipidemic effect and the effect is mediated by changes in peptide hormones. When lipid levels are very high as in obese rats, isoflavones fail to lower plasma triglyceride levels. Probiotics do not appear to enhance the effect of isoflavones.