Dietary Resistant Starch Prevents Urinary Excretion of Vitamin D Metabolites and Maintains Circulating 25-Hydroxycholecalciferol Concentrations in Zucker Diabetic Fatty Rats

Abstract

<p>It is common that individuals with type 2 diabetes (T2D) diagnosed with nephropathy exhibit suboptimal serum 25-hydroxycholecalciferol (25D) concentrations, which is the major circulating form of vitamin D. 25D is activated to 1,25-dihydroxycholecalciferol (1,25D) through enzyme activity in kidney. The objective of this study was to examine whether dietary resistant starch could prevent loss of vitamin D and maintain serum 25 D concentrations in Zucker diabetic fatty (ZDF) rats - a model with characteristics of human T2D. Control Zucker rats were fed with a standard semi-purified diet (AIN-93G); while ZDF rats were divided into two groups and fed with the control AIN-93G diet or the AIN-93G diet with cornstarch replaced by resistant starch (RS). The results indicated that the control diet-fed ZDF rats had 89% and 97% higher urinary excretion of 25 D and 1,25D, respectively, and 31% lower serum 25D concentrations than RS-fed ZDF rats. Also, RS reduced diabetes-mediated damage in kidney by 21% as indicated in histopathologic scoring system. Blood glucose level was shown 41% lower in RS-fed ZDF rats compared to control diet-fed ZDF. In conclusion, dietary resistant starch can help protect kidney health which in turn maintains vitamin D status in T2D.</p>