Effects of dietary allitol on the cecal microbiota profile and butyric acid production in high-fat diet-induced obese rats

Aim: To investigate the effects of allitol on the cecal microbiota profile of high-fat diet-induced obese rats to obtain basic data and to predict the pathway of butyric acid production from allitol using bioinformatic techniques. Moreover, this study examined whether the anti-obesity effect of allitol was due to butyric acid produced by gut microbiota. Methods: Sixteen male Wistar rats were divided into two groups: control (C) and 5% allitol-supplemented (A). The rats were provided free access to the experimental diets for 11 weeks. Following the feeding period, the body weight, body fat, cecal short-chain fatty acids, and cecal microbiota profiles were determined. Results: Body fat percentage was significantly lower in Group A than in Group C. Group A had a significantly higher abundance of the phylum Bacteroidota than Group C, whereas there were no differences in the abundance of Bacillota, Actinomycetota, and Pseudomonadota. Changes in the microbiota indicated a significant increase in the abundance of 10 genera and a significant decrease in the abundance of 14 genera in Group A compared to Group C. The cecal butyric acid content was significantly higher in Group A than in Group C. Functional analysis of PICRUSt2 showed that many enzymes belonging to the metabolic pathway that produces butyric acid from allitol are induced. However, the cecal bacteria involved in the anti-obesity effect differed from those involved in butyric acid production. Conclusions: This study demonstrated several compositional changes in the cecal microbiota and an increase in butyric acid production following dietary allitol supplementation. The anti-obesity effect of allitol was confirmed; however, it was suggested that the butyric acid produced by the intestinal bacteria may not be responsible for this effect.