Fig. 3: The Diet-microbiota subgroup: forest plot of mediation analysis for diet, potential gut microbiota mediators, and MS odds.

aMED alternative Mediterranean diet score, sp. unknown species Participants assessed include n = 27 MS cases and n = 32 controls. The “indirect effect” (blue circle) is the association of the dietary measure with MS risk mediated by the microbiota. Mediation by the microbiota is hypothesized when the indirect effect is significant. The “direct effect” (yellow circle) is the non-mediated association of diet with MS risk. The “total effect” (gray circle) is the combined mediated (indirect effect) and non-mediated (direct effect) association of the dietary intake (aMED or fiber intake) with MS risk. Because the total effect is dependent on the mediator, the total effect changes when the mediator is different. Results are represented as odds ratio (OR) adjusted for total energy intake, library size, the Bristol Stool Scale group, age at the FFQ completion and sex. An OR < 1 is a “protective” association and an OR > 1 is a ‘detrimental’ association. Only PCs and taxa significantly associated with both diet (aMED or fiber) and MS risk were displayed and tested for mediation. All Q-values of the indirect effect were >0.10 for aMED and >0.069 for fiber. The circles and error bars represent the mean and 95% confidence intervals of the OR, respectively. Thick error bars represent a significant association with MS risk (P < 0.05). Source data are provided as a Source Data File.