TNF and irritable bowel syndrome: Nonetheless, whether gut microbiota changes are a cause or effect of IBS remains unclear, however there are links between IBS‐associated dysbiosis and physiological alternations such as immune function with abnormal cytokine secretion (TNF‐a and IL‐6) [41], low‐grade inflammation [42], epithelial barrier dysfunction [43] and increased intestinal permeability [44] (Figure 1).