Galacto-oligosaccharides and gut bacteria in men with type 2 diabetes
What it found
Taking galacto-oligosaccharides for 12 weeks made no clear difference to blood sugar control or gut bacteria in men with type 2 diabetes.
The authors say the small group size and diabetes medication may have hidden any effects.
What they found
Studies in people
Blood sugar control
The galacto-oligosaccharide supplement did not change fasting blood sugar, insulin levels or overall blood sugar control compared with the placebo. Both groups saw a small rise in HbA1c over the 12 weeks.
Gut bacteria changes
The supplement did not significantly change the types or amounts of gut bacteria compared with the placebo. Bifidobacterium levels rose slightly in both groups, but the increase was not clearly different between them.
Gut lining strength
Taking the prebiotic fibre did not significantly change how leaky the gut lining was compared with the placebo.
Inflammation markers
The supplement did not change levels of inflammation markers or bacterial toxins in the blood compared with the placebo.
One bacterial family link
In the group taking the prebiotic, changes in one bacterial family called Veillonellaceae tracked closely with changes in blood sugar response and an inflammation marker called IL-6. This link needs more research to understand what it means.
What the authors conclude
- They conclude that 12 weeks of low-dose galacto-oligosaccharide supplementation did not improve blood sugar control in men with type 2 diabetes who were taking metformin.
- They suggest that the diabetes drug metformin may have masked any potential effects of the prebiotic fibre on gut bacteria.
- They note that their small sample size makes it hard to detect subtle changes, so they call for larger studies that account for diabetes medications.
How it was done
Animal studies suggest prebiotic fibres can improve gut bacteria, gut lining strength and blood sugar control. The authors wanted to see if this also happens in people with type 2 diabetes.
Twenty-nine men with well-controlled type 2 diabetes took either a galacto-oligosaccharide supplement or a placebo powder every day for 12 weeks. Each daily dose was 5·5 g mixed into food or drinks. The researchers measured gut bacteria, gut lining strength, inflammation and blood sugar control before and after.
What it can’t tell you
- Because only 29 men took part, the trial might have been too small to spot smaller benefits of the supplement.
- Everyone in the prebiotic group was taking metformin, which itself changes gut bacteria, so it is hard to separate the effects of the drug from the supplement.
- The study only looked at men with well-controlled diabetes, so the results may not apply to women or people whose diabetes is harder to manage.
Who paid
- Authors work at
- University of Surrey, UK; Royal Surrey County Hospital, UK; 3Animal and Plant Health Agency, UK
The paper
- Title
- Host-microbiome interactions in human type 2 diabetes following prebiotic fibre (galacto-oligosaccharide) intake
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Pedersen C, Gallagher E, Horton F, et al (2016). Host-microbiome interactions in human type 2 diabetes following prebiotic fibre (galacto-oligosaccharide) intake. The British journal of nutrition. doi:10.1017/S0007114516004086Free full textPubMed 27974055DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error