Soluble corn fiber and fish oil effects on gut bacteria in older adults
What it found
Taking soluble corn fiber with fish oil changed gut bacteria and cell signals linked to bowel cancer risk compared with maltodextrin and corn oil.
This was measured in 30 older adults over 30 days.
What they found
Studies in people
Blood fat levels
Levels of EPA and DHA fats in the blood were higher after taking soluble corn fiber with fish oil than after taking maltodextrin with corn oil.
Gut cell signals
The combination of soluble corn fiber and fish oil turned down a cell signal pathway related to glucose and insulin in the gut lining.
Gut bacteria mix
The overall mix of gut bacteria differed between the two options. Out of 73 bacterial groups checked, 27 differed, including several that make short chain fatty acids.
Butyrate making bacteria
Fewer Roseburia bacteria and less of their butyrate making gene were found after taking soluble corn fiber with fish oil compared with maltodextrin and corn oil. However, actual butyrate levels in stool stayed about the same.
What the authors conclude
- They conclude that 30 days of soluble corn fiber with fish oil shifted gut cell pathways linked to bowel cancer risk compared with maltodextrin and corn oil.
- They note this shift happened alongside changes in the gut bacterial community and the types of bacteria that make butyrate.
How it was done
Eating fiber and certain fats together lowers colon tumor formation in animals, but their combined effect on bowel cancer risk had not been tested in people. The authors wanted to see how these two ingredients work together in the gut of older adults.
Thirty adults aged 50 to 75 took part in a crossover trial. For 30 days they took 33 g per day of soluble corn fiber plus 7.7 g per day of fish oil, or similar amounts of maltodextrin plus corn oil. After a 60 day break they switched to the other option.
What it can’t tell you
- We summarised it from the abstract only.
- This was a small pilot study of 30 people, so scientists do not yet know if the results apply to everyone.
- The trial lasted only 30 days for each option, so it cannot show what happens over months or years.
- It measured gut signals and bacteria rather than actual cancer cases, so it cannot prove whether bowel cancer risk went up or down.
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 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error