Research

Mixed

Dietary fiber (specifically fermentable fibers like pectin) reduces the production of indole, a precursor to the uremic toxin indoxyl sulfate, by triggering catabolite repression of the tnaA gene in indole-producing gut bacteria (e.g., E. coli).

To support gut health and potentially reduce the production of harmful metabolites like indole, incorporate fermentable fibers (such as pectin found in apples) into your diet. This encourages beneficial bacteria to produce protective metabolites (ILA, IPA) and suppresses the production of indole, which is linked to chronic kidney disease risk.

GoodSupportsHIGH confidence
Importantly, fibre-degrading Bacteroides thetaiotaomicron affected this competition by cross-feeding monosaccharides to E. coli. This inhibited indole production through catabolite repression, thus making more tryptophan available to C. sporogenes, resulting in increased ILA and IPA production.
Anurag Kumar Sinha et al. · Nature Microbiology · 2024

Why this rating

Strong evidence from in vitro, gnotobiotic mouse, and human fecal culture models, though direct long-term human clinical outcomes on CKD are inferred from metabolite levels.

Source

Dietary fibre directs microbial tryptophan metabolism via metabolic interactions in the gut microbiota

Anurag Kumar Sinha et al. · Nature Microbiology · 2024

DOI 10.1038/s41564-024-01737-3

mechanism_onlyCited 212×
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DOI resolved against Crossref · corpus check 2026-06-10

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