Resistant starch type-4 intake alters circulating bile acids in human subjects

Area of Science:

• Microbiology
• Human Nutrition
• Metabolic Health

Background:

• Resistant starch type 4 (RS4) is a prebiotic fiber with known metabolic benefits.
• Bile acids (BAs) are key mediators of host-microbiota metabolic interactions.
• RS consumption impacts BAs, but effects on circulating BAs in humans are unknown.

Purpose of the Study:

• To investigate the impact of RS4 intake on circulating and fecal bile acid concentrations in humans.
• To explore potential alterations in the gut microbiome associated with RS4 consumption.

Main Methods:

• A double-blind, controlled crossover trial (NCT01887964) assessed changes after 12 weeks of 12 g/day RS4 intake.
• Liquid chromatography/mass spectrometry quantified bile acids in plasma and stool samples.
• Microbiome composition was analyzed using 16S rRNA gene sequencing and bioinformatics.

Main Results:

• RS4 intake significantly decreased stool BA concentrations and increased plasma concentrations of specific secondary BAs (e.g., taurodeoxycholic acid, deoxycholic acid).
• Distinct fecal and plasma BA signatures were observed post-RS4 intervention.
• RS4 consumption altered microbiome composition, with increased abundance of *Bifidobacterium adolescentis* associated with secondary BAs.

Conclusions:

• RS4 intake induces a novel, systemic alteration of microbiota-derived secondary bile acids in humans.
• These findings suggest RS4 modulates host metabolism through microbiome-bile acid interactions.
• Further research into RS4 and BA biosynthesis could reveal targets for manipulating microbiome-host interactions.