MSTN and gastrointestinal disease: Disease‐associated imbalances of the gut‐skeletal muscle axis are frequently accompanied, mediated and/or enhanced by a low‐grade systemic inflammation, characterized by increased levels of pro‐inflammatory cytokines (such as tumour necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6)), elevated circulating lipopolysaccharide (eg in gastrointestinal diseases) and a predominance of anti‐ vs pro‐myogenic mediators (eg myostatin vs insulin‐like growth factor‐1 (IGF‐1)).39, 48