Effects of Obesity and Feeding Avocado Extract on Gut Microbiota and Fecal Metabolomic Profile in Overweight/Obese Cats

Background/Objectives: Obesity is a growing problem in the feline population worldwide. An extract of unripe avocado (AvX) has been shown to attenuate gains in body weight and body fat in mice fed a high-fat diet. The aim of this study was to evaluate the effects of overweight/obesity and AvX on gut microbiota (GM) and fecal metabolomics in cats with natural overweight/obesity. Methods: Ten naturally overweight/obese and ten lean purpose-bred domestic shorthair cats were included in this study. In a prospective, randomized, double-blind study, one group of overweight/obese cats received AvX, while the second group received maltodextrin for 16 weeks. Fecal samples were collected after spontaneous defecation at specific time points and submitted for analysis. Fecal samples of overweight/obese cats collected before administration of AvX/maltodextrin were also compared to fecal samples of lean cats. Results: There was a significant difference in the clustering of GM over time in the AvX group and between lean and overweight/obese cats. The abundance of Firmicutes in the group of cats receiving AvX decreased compared to baseline. AvX induced a trend toward an increased abundance of Dialister sp. and a trend of decreased abundances of SMB53, Roseburia sp., Blautia producta, Acidaminococcus sp., Akkermansia sp., Adlercreutzia sp., and Collinsella aerofaciens. The metabolites that significantly differed after AvX administration included tryptophan, indole-3-acetate, nicotinamine, and glycyl-proline. At the species level, abundances of Prevotella sp., Turicibacter sp., Clostridium sp., Veillonella sp., Dialister sp., Catenibacterium sp., Eubacterium biforme, Desulfovibrio sp., and Campylobacter sp. were significantly higher in lean cats. Abundances of Coriobacterium sp. and Ruminococcus gnavus were significantly higher in overweight/obese cats. Additionally, LEfSe analysis identified Dialister as the genus associated with AvX administration and Dialister, Prevotella, Ruminococcus, Campylobacter, Catenibacterium, Clostridium, Helicobacter, Eubacterium, Pseudoramibacter, Veillonella, S247, Turicibacter, and Phascolarctobacterium as bacteria associated with the lean state. Genus Coriobacterium and Enterococcus were associated with overweight/obesity. A correlation between the concentration of metabolites significantly different between the AvX/placebo groups and the abundances of detected bacterial taxa at the genus level was assessed and described. Conclusions: There are significant differences in the GM between lean and overweight/obese cats. AvX consumption appears to affect the composition of GM and fecal metabolite concentrations in naturally overweight/obese cats.