We found that serum levels of C3 and CRP correlated with BMI in patients classified in IBS-C (C3, r = 0.49, p = 0.006; CRP, r = 0.53, p = 0.0025) and IBS-M (C3, r = 0.53, p = 0.0052; CRP, r = 0.40, p = 0.0383) subgroups (Figure 6). Here, C3 is linked to irritable bowel syndrome.