Science

Fernando F Anhê, Renato T Nachbar, Thibault V Varin, Jocelyn Trottier, Stéphanie Dudonné, Mélanie le Barz, Perrine Feutry, geneviève Pilon, Olivier Barbier, Yves Desjardins, Denis Roy, André Marette

Objective
The consumption of fruits is strongly associated with better health and higher bacterial diversity in the gut microbiota (gM). camu camu (Myrciaria dubia) is an amazonian fruit with a unique phytochemical profile, strong antioxidant potential and purported anti-inflammatory potential.
Design
By using metabolic tests coupled with 16S rrna gene-based taxonomic profiling and faecal microbial transplantation (FMt), we have assessed the effect of a crude extract of camu camu (cc) on obesity and associated immunometabolic disorders in high fat/ high sucrose (HFHS)-fed mice.
Results
Treatment of HFHS-fed mice with cc prevented weight gain, lowered fat accumulation and blunted metabolic inflammation and endotoxaemia. cc-treated mice displayed improved glucose tolerance and insulin sensitivity and were also fully protected against hepatic steatosis. these effects were linked to increased energy expenditure and upregulation of uncoupling protein 1 mrna expression in the brown adipose tissue (Bat) of cc-treated mice, which strongly correlated with the mrna expression of the membrane bile acid (Ba) receptor tgr5. Moreover, cc-treated mice showed altered plasma Ba pool size and composition and drastic changes in the gM (eg, bloom of Akkermansia muciniphila and a strong reduction of Lactobacillus). germ-free (gF) mice reconstituted with the gM of cc- treated mice gained less weight and displayed higher energy expenditure than gF-mice colonised with the FM of HFHS controls.
Conclusion
Our results show that cc prevents visceral and liver fat deposition through Bat activation and increased energy expenditure, a mechanism that is dependent on the gM and linked to major changes in the Ba pool size and composition.