Obesity-induced alterations in the gut microbiome in female mice fed a high-fat diet are antagonized by dietary supplementation with a novel, wax ester-rich, marine oil

Abstract Dietary supplementation with calanus oil, a novel wax ester-rich marine oil, has been shown to reduce adiposity in high-fat diet (HFD)-induced obese mice. Current evidence suggests that obesity and its comorbidities are intrinsically linked with unfavorable changes in the intestinal microbiome. Thus, in line with its anti-obesity effect, we hypothesized that dietary supplementation with calanus oil should counteract the obesity-related deleterious changes in the gut microbiota. Seven-week old female C57bl/6 J mice received an HFD for 12 weeks to induce obesity, followed by 8 weeks supplementation with 2% calanus oil. For comparative reasons, another group of mice was treated with exenatide, an anti-obesogenic GLP-1 receptor agonist. Mice fed normal chow diet (NCD) or non-supplemented HFD for 20 weeks served as lean and obese controls, respectively. 16S rRNA gene sequencing was performed on fecal samples from the colon. HFD increased the abundance of the Lactococcus and Leuconostoc genera relative to NCD, while abundances of Allobaculum and Oscillospira were decreased. Supplementation with calanus oil led to an apparent overrepresentation of Lactobacillus and Streptococcus and underrepresentation of Bilophila. Exenatide prevented the HFD-induced increase in Lactococcus and caused a decrease in the abundance of Streptococcus compared to the HFD group. Thus, a high-fat diet altered the gut microbiota composition in an unhealthy direction by increasing the abundance of pro-inflammatory genera, while reducing those considered health-promoting. These obesity-induced changes were antagonized by both calanus oil and exenatide.