Polydextrose and resistant starch change bile acids differently
What it found
In 74 healthy people, resistant starch raised bile acids in blood, while polydextrose lowered a bile acid change in stool.
The two fibres acted differently.
What they found
Studies in people
Blood bile acids
Resistant starch raised total bile acids in blood, including conjugated and secondary bile acids. Polydextrose did not change blood bile acids.
Stool bile acids
Neither fibre changed the total amount of bile acids in wet stool. Resistant starch lowered the share of primary bile acids, while polydextrose raised it.
Secondary bile acid change
Polydextrose lowered the ratios that show how much primary bile acids are turned into secondary ones. Resistant starch did not change these ratios.
Gut bacteria links
After resistant starch, a gut bacterium called Akkermansia was linked to higher levels of certain bile acids in blood. After polydextrose, links between certain gut bacteria and bile acid ratios changed.
What the authors conclude
“RS increased plasma BAs, particularly conjugated BAs, whereas PD reduced faecal secondary BA transformation.”
Also in their conclusions
- They conclude that resistant starch and polydextrose have distinct effects on bile acid profiles in blood and stool.
- They say further studies are needed to evaluate the health consequences of resistant starch increasing circulating bile acids, especially for glucose metabolism and colorectal cancer risk.
- Their findings suggest that the different fermentation properties of the fibres may explain the effects.
How it was done
The authors wanted to test whether fibres that ferment at different speeds have different effects on bile acids, because bile acids are linked to gut and metabolic health.
They analysed blood and stool samples from a 50-day randomised trial where 75 healthy people took either resistant starch, polydextrose, both, or placebos. Blood bile acids were measured in 74 people and stool bile acids in 50.
What it can’t tell you
- This was a secondary analysis without a planned sample size, which may limit statistical power.
- The study cannot show whether the changes in bile acids affect long-term health outcomes like cancer or diabetes.
- The study did not measure daily stool output, so it cannot show whether the fibres changed how much bile acid was excreted.
Who paid
- Funding
- Funded by Wellcome Trust; Biotechnology and Biological Sciences Research Council (from the PubMed record).
- Conflicts
- Declarations. Conflict of interest: The authors declare that they have no conflicts of interest. Ethical approval: for the DISC Study was granted by the Newcastle and North Tyneside Research Ethics Committee on 10th December 2009 (REC No. 09/H0907/77) and Caldicott approval for the storage of data was provided by the Northumbria NHS Foundation Trust (C1792). The study has therefore been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.
- Authors work at
- Newcastle University, UK; University of East Anglia, UK; Northumbria University, UK
The paper
- Title
- Distinct effects of supplementation with resistant starch and polydextrose on plasma and faecal bile acid profile and associations with gut microbiota: a randomised, controlled intervention in healthy participants
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Fan J, le Gall G, Malcomson FC, et al (2026). Distinct effects of supplementation with resistant starch and polydextrose on plasma and faecal bile acid profile and associations with gut microbiota: a randomised, controlled intervention in healthy participants. European journal of nutrition. doi:10.1007/s00394-026-04060-1Free full textPubMed 42489745DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error