Effects of Wheat Starch-Mung Bean Hull Polyphenol Complex-based Resistant Starch on Gut Microbiota and Their Metabolites in Diabetes Patients

To evaluate the prebiotics of wheat starch-mung bean hull polyphenol complex-based resistant starch (WS-MBPs-R) on the intestinal tract of T2DM patients, this study used the in vitro fermentation model, with wheat starch-based resistant starch (WS-R) and wheat starch-based resistant starch/mung bean skin polyphenols mixture (WS-R/MBPs) as positive controls, to determine the pH, gas production, reducing sugar content and short chain fatty acids (SCFAs) content of the fermentation broth at different times, and analyzed the impact of WS-MBPs-R on the intestinal flora of diabetes patients by 16S rRNA sequencing. Meanwhile, the multi-scale structural changes of WS-MBPs-R during the fermentation process were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The results showed that compared with the negative (without carbon source) and positive control groups, the pH of the fermentation broth in the WS-MBPs-R group significantly decreased to 4.47 after 24 hours of fermentation, while the gas production significantly increased to 8.6 mL (P<0.05). Fermentation with three types of resistant starch promoted the production of SCFAs, especially WS-MBPs-R, whose total SCFAs concentration reached 246.51±3.01 mmol/L after fermentation for 24 h. WS-MBPs-R fermentation could improve the intestinal flora structure of diabetes patients, promote the proliferation of beneficial bacteria such as Prevotella and Bifidobacterium, and inhibit the growth of harmful bacteria such as Escherichia_Shigella and Fusobacterium. After fermentation, the short-range ordered structure and total crystallinity of WS-MBPs-R increased, indicating that gut microbiota preferentially utilized the amorphous region of resistant starch. In conclusion, WS-MBPs-R, a new type of resistant starch, has good probiotics and can be developed and utilized as a functional food raw material for people with diabetes.