Eating some fiber and increasing the production of short-chain fatty acids in the gut would improve insulin sensitivity and glucose control in obese or overweight people.
In a population of overweight or obese individuals, producing short-chain fatty acids by the gut microbiota by eating highly fermentable fiber plays an anti-inflammatory role throughout the body and improves insulin sensitivity. This result is obtained from a controlled study with all the criteria of methodological quality, which is rare in nutrition. It is published in the journal Gut.
A quality study
The study compared the administration of a highly fermentable dietary fiber precursor (inulin-propionate ester) to a diet rich in low fermentable fiber (cellulose). Inulin-propionate ester is a dietary supplement in the form of a powder, which is degraded by propionate bacteria in the intestine and then into short chain fatty acid.
It has already been shown that short-chain fatty acids (SCFA), which are therefore products of the bacterial fermentation of certain dietary fibers by bacteria in the colon, are involved in our sugar metabolism and improve the sensitivity to insulin.
An anti-inflammatory role
This new study analyzes the mechanisms underlying the action of the inulin-propionate ester. To do this, the researchers analyzed the intestinal bacterial composition, the plasma metabolome and the immune responses of 12 obese or overweight volunteers, but not diabetics.
Each of them received either 20 grams per day of inulin-propionate ester, delivering propionate into the colon, a highly fermentable fiber, or the same amount of a non-fermentable fiber, cellulose, which plays the role of placebo, and this in 42-day sequences. The scientists analyzed the participants' metabolic responses, inflammatory markers and intestinal bacterial composition.
The researchers found that the inulin-propionate ester improved insulin resistance, especially on an empty stomach. Inulin-propionate also promoted changes in bacterial populations (resulting in an increase in the number of actinobacteria and a decrease in the number of Clostridia). More precisely, it has favored a bifidogenic effect.
The limits of this research
According to the researchers, these data demonstrate that the administration of propionate in the colon in humans has a major physiological impact and that this benefit can be obtained by eating fermentable fiber or by taking a dietary supplement that delivers this type of fiber.
The improvement in insulin sensitivity promoted by inulin-propionate with different effects in populations of intestinal bacteria and markers of systemic inflammation, new studies will be needed, on a larger panel of people.
It would have distinct effects on the intestinal microbiota (populations of bacteria in the intestine), on the plasma metabolome (used to identify new biomarkers predicting the risk of developing certain pathologies) and decrease systemic inflammatory responses.