Noble Rats Display Decreased Weight Gain and Visceral Adiposity via Lifelong Exposure to an Isoflavone-Rich Diet

Abstract

Obesity and cancer represent two of the greatest public health concerns. The relationship between obesity and cancer suggests an important role for visceral adipose tissue (VAT) versus generalized body fat. Male and female Noble rats develop a relatively high incidence of spontaneous and hormone-induced carcinomas. The main purpose of this study was to make an initial assessment of whether a high soy-isoflavonoid diet could decrease VAT and reduce overall body weight gain in Noble rats. The male and female rats were exposed solely to either a high soy-isoflavonoid diet (High-Iso) or a low-isoflavonoid diet (Low-Iso) from conception to adulthood. At the end of the experiment, at 145 days of age, overall weight gain and visceral fat deposition were recorded along with quantification of serum isoflavone levels (genistein, daidzein and equol). Serum isoflavone levels in the High-Iso treatment groups were significantly higher (by approximately 15-fold) compared to animals in the LowIso diet groups. Male and female Nobel rats fed the High-Iso diet displayed significantly lower body weight gain (by approximately 10%) compared to animals fed the Low-Iso diet. Notably, VAT deposition was reduced by 61% in females but 21% in males fed the High-Iso diet versus the Low-Iso diet. In summary, consumption of a diet high in isoflavones significantly lowered body weight and VAT deposition and a hypothesis may be proposed as to how soy-derived isoflavones may decrease VAT storage areas to potentially improve obesity and cancer outcomes.