Fermented brown rice beverage distinctively modulates the gut microbiota in Okinawans with metabolic syndrome: A randomized controlled trial

Accumulating evidence to date suggests that brown rice is superior to white rice in regard to its beneficial impact on a number of risk factors of the metabolic syndrome (MetS). However, little is known about the influence of fermented brown rice beverage on the gut microbiota in humans. We therefore hypothesized that its impact would beneficially alter the gut microbiota composition of patients with MetS. Using a 4-week randomized, single-arm study design, subjects (n = 40) were advised to consume a daily fermented brown rice beverage (BA) or fermented white rice beverage (WA) as a replacement of their main meal. Clinical and anthropometric measurements as well as fecal samples were collected at baseline and immediately after completion of the intervention. Gut microbiota was analyzed using 16S ribosomal RNA sequencing and capillary electrophoresis-time-of-flight mass spectrometry was used to measure plasma short-chain fatty acids. Interestingly, ingestion of BA in contrast to WA resulted in a unique elevation in the abundance of number of beneficial species belonging to the Clostridia class, associated with reduced inflammation, and increased short-chain fatty acid production: Lactobacillales bacterium DJF B280 ( P = .005), Butyrate producing bacterium A2 207 ( P = .012), and Firmicutes bacterium DJF VP44 ( P = .038). This study demonstrates that consumption of BA is effective to beneficially modulate the gut microbiota compared with WA in patients with MetS.(c) 2022 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/)

Automated summary

This study found that brown rice has a positive impact on the gut microbiota of patients with metabolic syndrome compared to white rice. Consuming a fermented brown rice beverage resulted in an increase in beneficial species of bacteria associated with reduced inflammation and increased short-chain fatty acid production.