Results
Totals of 214 and 167 patients completed the two parts of the study, respectively. After intervention, IBS‐D‐SSS and TIgG grade were significantly improved compared to baseline, with results similar to the control group. In general, there were decreases in IBS‐D‐SSS and TIgG grade that were significantly different among the groups. There were exceptions; no differences were observed for IBS‐D‐SSS between the IgG res diet and CSF + IgG res diet, or TIgG grade between the CSF res diet, IgG res diet, and CSF + IgG res diet. However, the CSF res diet and IgG res diet had a synergistic effect that decreased IBS‐D‐SSS and TIgG titer, with a greater contribution by the IgG res diet. Therefore, we evaluated the IgG res diet with either placebo or probiotic and found that IBS‐D‐SSS and TIgG grade decreased from baseline. There was a significant decrease in IBS‐D‐SSS with the probiotic but TIgG grade was not significantly different between the IgG diet + placebo and IgG diet + probiotic diet.