Brown rice-based diet substitution to improve gut microbiota profile, short-chain fatty acid levels, and metabolic markers of type 2 diabetes patients

Gut microbiota plays a significant role in controlling type 2 diabetes (T2D). Brown rice (BR) has higher fiber and magnesium contents, and also a lower glycemic index than white rice (WR), thus might be potentially able to improve gut microbiota, short-chain fatty acid (SCFA), and metabolic markers. This study aimed to compare gut microbiota profile, SCFA level, and changes in anthropometric and laboratory metabolic markers of T2D patients given 12 weeks of BR and WR-based diet. This experimental pre-post test design study enrolled 17 female-diabetic patients with oral antidiabetic drugs (OAD) using purposive sampling methods. Subjects were given a BR-based diet for 12 weeks, followed by washing-out for 2 weeks, and a WR-based diet for 12 weeks. Gut microbiota profiles and SCFA were evaluated using quantitative real-time PCR (qPCR) and gas chromatography (GC). After BR intervention, subjects had a higher relative abundance of Firmicutes, lower Bacteroidetes, higher Firmicutes to Bacteroidetes (F/B) ratio, and higher levels of butyrate compared to WR. Moreover, BR significantly improved anthropometric and laboratory metabolic markers and homeostasis model assessment for insulin resistance (HOMA-IR) index (p<0.05). T2D patients given a BR-based diet for 12 weeks had better gut microbiota profiles, butyrate levels, anthropometric and laboratory metabolic markers, and insulin resistance.