Galacto-oligosaccharides, gut bacteria and insulin sensitivity in prediabetic people
What it found
Taking galacto-oligosaccharides for 12 weeks raised one type of gut bacteria five-fold in overweight, prediabetic people.
It did not change how their bodies handled sugar or fat.
What they found
Studies in people
More Bifidobacterium in stool
People taking galacto-oligosaccharides had five times more Bifidobacterium in their stool after 12 weeks. The placebo group saw no such rise. The overall variety of gut bacteria stayed the same.
No change in insulin sensitivity
The main goal was to see if the supplement helped the body respond better to insulin. After 12 weeks, there was no difference between the two groups in how well their bodies used insulin.
Fatty acids stayed the same
When gut bacteria break down fiber, they make short-chain fatty acids. Levels of these acids in stool and blood were about the same in both groups at the end of the trial.
Body weight unchanged
Body weight, body fat percentage and belly fat did not differ between the people taking the supplement and those taking the placebo.
Inflammation markers unchanged
Blood markers linked to inflammation and gut hormones showed no differences between the two groups after 12 weeks.
What the authors conclude
- They conclude that 12 weeks of galacto-oligosaccharides reliably increased Bifidobacterium in the stool of overweight, prediabetic adults.
- They note that this large rise in one type of gut bacteria did not lead to improvements in insulin sensitivity, energy use or inflammation markers.
- They suggest that simply changing the mix of gut bacteria toward more Bifidobacterium does not automatically improve metabolism in people who are already prediabetic.
How it was done
Gut bacteria help control blood sugar, fat storage and inflammation. The authors wanted to see if feeding these bacteria with galacto-oligosaccharides would improve metabolism over the long term.
They gave 44 overweight or obese men and women with prediabetes either 15 g of galacto-oligosaccharides or a placebo every day for 12 weeks. Before and after, they measured gut bacteria, blood sugar handling, body fat and inflammation markers.
What it can’t tell you
- This trial only looked at fasting measurements, so it cannot show what happens to blood fats or acids in the hours right after eating.
- The study focused on overweight, prediabetic adults aged 45 to 70, so the results might not apply to younger people or those without prediabetes.
Who paid
- Authors work at
- Top Institute Food and Nutrition, The Netherlands; Maastricht University Medical Centre+, The Netherlands; Wageningen University, The Netherlands
The paper
- Title
- Supplementation of Diet With Galacto-oligosaccharides Increases Bifidobacteria, but Not Insulin Sensitivity, in Obese Prediabetic Individuals
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Canfora EE, van der Beek CM, Hermes GDA, et al (2017). Supplementation of Diet With Galacto-oligosaccharides Increases Bifidobacteria, but Not Insulin Sensitivity, in Obese Prediabetic Individuals. Gastroenterology. doi:10.1053/j.gastro.2017.03.051Free full textPubMed 28396144DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error