Oatmeal-based fiber diet outperforms resistant starch-based fiber diet in lowering serum uric acid via gut microbiota–metabolite interactions: a randomized controlled trial

Abstract

Elevated serum uric acid (SUA) in young adults increases the risk of gout and urolithiasis later in life. While dietary fiber is known to lower SUA, the comparative effects of different fiber sources remain unclear. This 8-week, three-arm randomized controlled trial compared the SUA-lowering efficacy of oatmeal (OM) and resistant starch rice (RS) and explored underlying microbial and metabolic mechanisms. 99 undergraduate participants were randomly assigned to OM, RS, and control groups, with standardized meal plans ensuring comparable nutrient intake. The results indicate that both high-fiber diets significantly reduced SUA compared with the control group (ANOVA, P < 0.05), with a greater reduction observed in the OM group than in the RS group (ΔSUA: −64.5 µmol L⁻¹ vs. −39.0 µmol L⁻¹, P < 0.05). Multi-omics analyses identified post-intervention enrichment of Dialister in the OM group and changes in its microbial co-occurrence network. Mediation analysis further revealed threo-syringoylglycerol as a key metabolite linking increased Dialister abundance to SUA reduction. In conclusion, the OM-based diet exhibited a more pronounced SUA-lowering effect than the RS-based diet, potentially associated with Dialister enrichment and related metabolic alterations. These findings support oatmeal as an effective high-fiber strategy for managing SUA in young adults.