In discriminating IBS subtypes from controls, only diarrhoeal IBS (IBS-D) could be distinguished by albumin (3 studies, 248 controls and 219 IBS-D, SMD = -0.39, 95% CI = -0.68, -0.11, p = 0.007) and IL-6 (4 studies, 153 IBS-D and 169 controls, SMD = 2.53, 95% CI = 0.86, 4.21, p = 0.003). This evidence concerns the gene IL6 and irritable bowel syndrome.