Siel et al., 2020. Link between gut microbiota and health outcomes in inulin-treated obese patients: Lessons from the Food4Gut multicenter randomized placebo-controlled trial. Clinical Nutrition

This is a summary of our DalMUG journal club discussion written by Vanessa DeClercq

Summary

The gut microbiota is altered in individuals living with obesity and may be influenced by specific foods or nutrients in the diet. Vegetables rich in dietary fibres, such as inulin can act as prebiotics, becoming metabolized by microorganisms within the gut and offering potential beneficial health properties. The study aimed to examine if a combination intervention (inulin rich diet plus insulin supplements) was an effective way to manipulate the diet and control weight gain and metabolic disorders in adults living with obesity. This was a parallel energy restriction intervention that included male and female participants with a BMI>30 and sample collection at both baseline and 3 months. The results showed that both diets were effective at restricting energy intake and improving some metabolic outcomes, with the probiotic group showing additional metabolic benefits along with shifts in specific bacteria. One of the main findings was that metformin treatment attenuated changes in the gut microbiome and some metabolic parameters. Finally, analysis of metformin naive patients alone demonstrated changes in specific gut microbes that were associated with distinct metabolic improvements.

Points of Interest

• The addition of inulin to the diet offers a potential way to improve obesity-associated metabolic complications and gut dysbiosis.
• Treatment with inulin appears more efficacious in metformin naïve patients, highlighting the need to consider both diet and medication use when attempting to target or manipulate the gut microbiota and metabolic parameters.

Points of Concern

• Limitations of Food Frequency Questionnaires (FFQs) are well documented. An additional method (e.g. 24hr recall) would have strengthened FFQ data.
• Some of the initial microbial changes shown with prebiotic treatments were not presented in the split analysis of metformin and metformin naïve patients.
• The last figure, which was probably one of the most interesting, showed correlations between changes in metabolic parameters and bacterial general in metformin-naïve patients but it was extremely hard to interpret (readers need to account for double negatives to interpret the direction of the relationship).