Table 4: The total, direct, and indirect (mediated) effects of NNSs on faecal SCFA. The results are presented for the SCFA that were statistically significantly associated with NNSs, and the indirect (mediated) effects are shown for the bacterial groups and species significantly associated with NNSs.

Dependent variableMediatorTotal effect of NNS
B (95% CI), value
Direct effect of NNS
B (95% CI), value
Indirect effect via mediator
B (95% CI)

Butyric acidDysbiosis Index−0.159 (−0.281 to −0.037), 0.011−0.148 (−0.279 to −0.016), 0.029−0.011 (−0.061 to 0.033)
Butyric acidAlternative Dysbiosis Index−0.159 (−0.281 to −0.037), 0.011−0.159 (−0.289 to −0.029), 0.0160.000 (−0.040 to 0.049)
Butyric acidFaecalibacterium prausnitzii−0.159 (−0.281 to −0.037), 0.011−0.176 (−0.303 to −0.049), 0.0070.017 (−0.022 to 0.073)
Butyric acidBacteroides fragilis−0.159 (−0.281 to −0.037), 0.011−0.149 (−0.281 to −0.017), 0.027−0.010 (−0.051 to 0.024)
Butyric acidRuminococcus gnavus−0.159 (−0.281 to −0.037), 0.011−0.162 (−0.292 to −0.031), 0.0160.003 (−0.023 to 0.048)
Butyric acidStreptococcus spp.−0.159 (−0.281 to −0.037), 0.011−0.152 (−0.282 to −0.023), 0.022−0.006 (−0.034 to 0.018)
Valeric acidDysbiosis Index−0.022 (−0.043 to −0.002), 0.029−0.025 (−0.046 to −0.003), 0.0270.002 (−0.004 to 0.010)
Valeric acidAlternative Dysbiosis Index−0.022 (−0.043 to −0.002), 0.029−0.022 (−0.044 to −0.001), 0.045−0.001 (−0.008 to 0.008)
Valeric acidFaecalibacterium prausnitzii−0.022 (−0.043 to −0.002), 0.029−0.029 (−0.050 to −0.009), 0.0060.007 (−0.001 to 0.018)
Valeric acidBacteroides fragilis−0.022 (−0.043 to −0.002), 0.029−0.022 (−0.044 to −0.001), 0.046−0.000 (−0.008 to 0.008)
Valeric acidRuminococcus gnavus−0.022 (−0.043 to −0.002), 0.029−0.020 (−0.041 to 0.002), 0.069−0.003 (−0.010 to 0.006)
Valeric acidStreptococcus spp.−0.022 (−0.043 to −0.002), 0.029−0.023 (−0.045 to −0.002), 0.032−0.001 (−0.003 to 0.007)