Soybean Okara modulates gut microbiota in rats fed a high-fat diet

Okara is a valuable and abundant by-product from soybean processing which has a high dietary fibre content, mainly composed of insoluble fibre. In order to increase its solubility, a high hydrostatic pressure treatment combined with Ultraflo® L enzyme was applied to prepare a soluble dietary fibre-enriched Okara. Then, its healthy effects were tested in Wistar rats fed a high-fat diet supplemented with 20% treated Okara for four weeks. Okara induced weight-loss, reduced plasma triglycerides (1.4-times) and improved amino-acid metabolism (1.2-times lower urea) compared to the control. Regarding its prebiotic status, Okara enhanced short chain fatty acids release and improved calcium and magnesium absorption. Moreover, quantitative PCR analysis of selected bacterial groups showed that Okara restored the values of several beneficial groups in gut microbiota and prevented the bacterial drop caused by a high-fat diet. Therefore, Okara exerts health-promoting benefits in vivo and could be further used like a prebiotic and functional ingredient in foods.