Table 2.

Possible roles of SIBO subtype in PD progression.

SIBO Subtype *	Presumptive Roles in PD Progression
H2-predominant SIBO	Protective: anti-inflammatory, decreases oxidative stress.Uncertain: modulates the gut microbiota (reinforces hydrogenotrophic bacteria and archaea); increased production of hydrogen sulfide.
Methane-predominant SIBO	Either protective or deleterious: may counteract protein misfolding and may effectively remove aggregates of misfolded proteins; proinflammatory and may increase aggregation of misfolded proteins.

* As per carbohydrate (i.e., lactulose) breath test.