Body composition is associated with gut microbiota variations in a group of free-living adults with cystic fibrosis (CF)

![CDATA[Objectives: Although undernutrition undermines lung function and survival in CF, excessive adiposity seems to offer limited advantage to lung health and may increase long term obesity-related disease risk in the CF population with increased life expectancies and overweight/obesity prevalence. Emerging evidence indicates associations between gut microbiota (GM) variations and weight changes, possibly partly via diet- GM interactions in host immunity and energy homeostasis. In CF, GM shows a clear dysbiosis, and GM variation appears associated with respiratory manifestations. Thus, the GM may affect, and partly mediate associations between nutritional status and respiratory outcomes in CF. This study investigated associations between GM and nutritional status (e.g. anthropometry and body composition) in adults with CF. Methods: In a cross-sectional study of 16 adults with CF the composition of the GM (fecal) was profiled by 16ss rDNA sequencing. Composition of the GM was associated with various clinical characteristics including anthropometric and body composition measurements. Results: Body fat mass and percentage of body fat were associated with fecal microbiota variations (p < 0.04, R2 > 0.08, FDR < 0.3,adonis of UniFrac distances) and both correlated negatively with Firmicutes (p = 0.01, r = −0.6, FDR = 0.2). Conclusion: The results highlight the potential relevance of GM, particularly Firmicutes, to body composition (hence energy homeostasis) in CF. Considering linkages between lung function, survival and nutritional status in CF, the potential interplay between body composition, GM and CF progression requires further evaluation towards optimizing CF nutritional management.]]