Objective  The purpose of this study was to investigate the effects of dietary supplementation of different conjugated linoleic acid (CLA) isomers on body fat, energy metabolism and gut microbiota in mice.

Method  Mice were fed with normal diet (control group), normal diet supplemented with 2% cis-9, trans-11 conjugated linoleic acid (c9, t11-CLA) and trans-10, cis-12 conjugated linoleic acid (t10, c12-CLA) for 12 weeks respectively. The changes of fat content, energy metabolism and gut microbiota were detected.

Result  Compared with the control group, the body weight of mice in the c9, t11-CLA and t10, c12-CLA groups decreased by 22.79% and 25.04% respectively, the fat contents decreased by 57.98% and 59.41% respectively, and the contents of subcutaneous fat, epididymal white fat and brown fat also decreased significantly. In addition, c9, t11-CLA and t10, c12-CLA significantly increased oxygen consumption and heat production in mice, and t10, c12-CLA significantly decreased the nocturnal respiratory exchange rate. The 16S rRNA sequencing results showed that there were obvious differences in gut microbial community structure among three groups of mice. The abundances of metabolism-related flora in the guts of mice in c9, t11-CLA and t10, c12-CLA groups were significantly higher than that in the control group, and t10, c12-CLA could promote the up-regulation of lipid metabolism-related flora. At the phylum level, compared with the control group, the relative abundances of Firmicutes and Actinobacteria in c9, t11-CLA and t10, c12-CLA groups were significantly up-regulated, while the relative abundances of Bacteroidetes and Verrucomicrobia were significantly down-regulated. At the genus level, compared with the control group, the relative abundance of Bifidobacterium in c9, t11-CLA group was significantly up-regulated, while the relative abundances of Ileibacterium and Akkermansia were significantly down-regulated.

Conclusion  Dietary supplementation with c9, t11-CLA or t10, c12-CLA can significantly reduce fat deposition in mice, which may be related to the elevated energy metabolism and altered gut microbial community structure induced by CLA.