Potato starch and gut bacteria in a 4-week trial
What it found
In a 4-week trial in healthy adults, 3.5 g of resistant potato starch daily increased two types of gut bacteria and reduced both diarrhea- and constipation-associated bowel movements compared to a placebo.
The 7 g dose showed similar trends but fewer clear differences.
What they found
Studies in people
Bifidobacterium increase
After 4 weeks, the 3.5 g potato starch group had a significantly greater increase in Bifidobacterium than the placebo group. The 7 g group also showed an increase, but it was not statistically significant.
Akkermansia increase
The 3.5 g potato starch group had a significantly greater increase in Akkermansia than the placebo group. The 7 g group showed a trend toward an increase that was not statistically significant.
Bowel movements
The 3.5 g group had significantly fewer diarrhea-associated (Type 7) and constipation-associated (Type 1 or 2) bowel movements than the placebo group. The 7 g group had significantly fewer of some diarrhea-associated types (Types 5, 6, or 7).
Side effects
Similar numbers of people in each group reported side effects, mostly gastrointestinal like flatulence and bloating. There were no serious side effects.
What the authors conclude
“We demonstrate that RPS has a prebiotic effect at a 3.5 g daily dose, which is comparable to prebiotic oligosaccharide doses (i.e., 3–7 g/day; [ 59 ]).”
Also in their conclusions
- They conclude that resistant potato starch has a prebiotic effect at a 3.5 g daily dose, increasing Bifidobacterium and Akkermansia and reducing both diarrhea- and constipation-associated bowel movements compared to placebo.
- They state that resistant potato starch was safe and well tolerated at both 3.5 g and 7 g daily doses.
- They call for future studies on other benefits at low doses and in people with IBS.
How it was done
High doses of resistant starch have been studied, but the authors wanted to see if a low dose, similar to amounts used for other prebiotics, could still boost beneficial gut bacteria and improve stool consistency.
They randomly assigned 75 healthy adults to take 3.5 g or 7 g of resistant potato starch or a placebo daily for 4 weeks. Stool samples were analyzed for Bifidobacterium and Akkermansia, and participants recorded their bowel movements using the Bristol Stool Form Scale.
What it can’t tell you
- The study lasted only 4 weeks, so it cannot show whether the effects on gut bacteria and bowel movements last longer.
- The participants were healthy adults without digestive conditions, so the results may not apply to people with IBS or other gut disorders.
- The study cannot prove that the changes in gut bacteria directly caused the improvements in bowel movements.
Who paid
- Conflicts
- Jason R. Bush is employed by and Michelle J. Alfa and Scott V. Harding previously provided consulting services for MSP Starch Products Inc., Carberry, MB, Canada. Joshua Baisley is employed by Nutrasource Pharmaceutical and Nutraceutical Services, Guelph, ON, the company that MSP Starch Products contracted to conduct the study. MSP Starch Products Inc.’s sister company McPharma Biotech holds relevant patents US11058711B2, CA3024201A1, and AU2017294806A1.
- Authors work at
- Memorial University of Newfoundland, Canada
The paper
- Title
- Consumption of Solnul ™ Resistant Potato Starch Produces a Prebiotic Effect in a Randomized, Placebo-Controlled Clinical Trial
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Bush JR, Baisley J, Harding SV, Alfa MJ (2023). Consumption of Solnul ™ Resistant Potato Starch Produces a Prebiotic Effect in a Randomized, Placebo-Controlled Clinical Trial. Nutrients. doi:10.3390/nu15071582Free full textPubMed 37049425DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error