Effect of genistein, a soy isoflavone, on whole body insulin sensitivity and renal damage induced by a high-fructose diet.

The study evaluates the effect of genistein, a soy isoflavone, on insulin sensitivity and renal functional and structural injury in rats rendered insulin-resistant by feeding on a high-fructose diet for 60 days. Fructose-fed animals (60 g /100 g) displayed insulin resistance as indicated by the measures of insulin sensitivity [insulin sensitivity index (ISI(0,120)), quantitative insulin check index (QUICKI), and homeostatic model assessment (HOMA)]. Alterations in body weight, kidney weight, urine volume, plasma, and urine electrolytes accompanied by significant increases in plasma and urinary levels of urea, uric acid, creatinine, total protein, and albumin were observed in fructose-fed rats. Oxidative stress in kidney was noted by an elevation in lipid peroxides and a decline in glutathione (GSH). Insulin sensitivity and renal function were improved in fructose-fed rats administered genistein. Histological changes such as fatty infiltration and thickening of glomeruli observed in fructose-fed rats were also ameliorated when genistein was co-administered. The study shows that genistein improves insulin sensitivity and kidney function in a dietary model of insulin resistance. We suggest that genistein may have benefits for patients suffering from kidney disease associated with insulin resistance.