Corn fiber with fish oil and gut changes in older adults
What it found
In 30 healthy older adults, taking soluble corn fiber with fish oil for 30 days changed gut bacteria and gut cell pathways compared with maltodextrin and corn oil.
The two groups did not differ in fecal butyrate levels.
What they found
Studies in people
Blood fatty acids
Blood levels of EPA and DHA were higher after the corn fiber plus fish oil period than after the maltodextrin plus corn oil period.
Gut cell pathways
The corn fiber plus fish oil combination inhibited a glucose-insulin receptor signaling pathway in gut cells, based on RNA analysis.
Gut bacteria diversity
The overall mix of gut bacteria differed between the two treatments. Of 73 bacterial groups analyzed, 27 differed, including several known short-chain fatty acid producers.
Roseburia and butyrate
A butyrate kinase gene from Roseburia and the Roseburia bacterial group were less abundant after corn fiber plus fish oil than after maltodextrin plus corn oil. However, fecal butyrate concentrations did not differ between the two treatments.
What the authors conclude
“Thirty-day supplementation of SCF + FO compared with MD + CO showed significant shifts in intestinal cell pathways relevant to colorectal cancer with concomitant differences in gut microbial community structure and butyrate-producing taxa.”
Also in their conclusions
- They conclude that 30-day supplementation of soluble corn fiber plus fish oil compared with maltodextrin plus corn oil showed significant shifts in intestinal cell pathways relevant to colorectal cancer.
- They also note concomitant differences in gut microbial community structure and butyrate-producing taxa.
How it was done
Eating dietary fiber and n-3 polyunsaturated fatty acids together reduces colon tumor formation, but their combined effects on colorectal cancer risk had not been tested in human trials.
Thirty adults aged 50 to 75 took either 33 g per day of soluble corn fiber plus 7.7 g per day of EPA and DHA from fish oil, or similar doses of maltodextrin plus corn oil, for 30 days. After a 60-day washout, they switched to the other treatment. The researchers analyzed blood fatty acids, gut cell RNA, gut bacteria, a butyrate kinase gene, and fecal short-chain fatty acids.
What it can’t tell you
- We summarised it from the abstract only.
- This was a 30-day pilot study in 30 healthy older adults, so it cannot show whether these gut changes affect colorectal cancer risk over time.
- The study measured gut cell pathways and bacterial changes, not cancer outcomes.
Who paid
- Funding
- Funded by NCI NIH HHS; NIDDK NIH HHS (from the PubMed record).
- Conflicts
- Conflict of interest The authors report no conflicts of interest.
- Authors work at
- Fred Hutchinson Cancer Center, United States; Texas A&M University, United States; University of Washington, United States
The paper
- Title
- Gut microbial community and host intestinal gene expression with combined fish oil and soluble corn fiber compared with corn oil and maltodextrin: A randomized crossover trial in healthy older individuals
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Abstract only
- Cite
- Moosavi D, Mullens DA, Davidson LA, et al (2025). Gut microbial community and host intestinal gene expression with combined fish oil and soluble corn fiber compared with corn oil and maltodextrin: A randomized crossover trial in healthy older individuals. The American journal of clinical nutrition. doi:10.1016/j.ajcnut.2025.04.031Free full textPubMed 40754387DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error