Small Intestinal Bacterial Overgrowth as Potential Therapeutic Target in Parkinson's Disease

Int J Mol Sci. 2021 Oct 28;22(21):11663. doi: 10.3390/ijms222111663.


Increasing evidence suggests that the gut microbiota and the brain are closely connected via the so-called gut-brain axis. Small intestinal bacterial overgrowth (SIBO) is a gut dysbiosis in which the small intestine is abundantly colonized by bacteria that are typically found in the colon. Though not a disease, it may result in intestinal symptoms caused by the accumulation of microbial gases in the intestine. Intestinal inflammation, malabsorption and vitamin imbalances may also develop. SIBO can be eradicated by one or several courses of antibiotics but reappears if the predisposing condition persists. Parkinson's disease (PD) is a common neurodegenerative proteinopathy for which disease modifying interventions are not available. Sporadic forms may start in the gut years before the development of clinical features. Increased gastrointestinal transit time is present in most people with PD early during the course of the disease, predisposing to gut dysbiosis, including SIBO. The role that gut dysbiosis may play in the etiopathogenesis of PD is not fully understood yet. Here, we discuss the possibility that SIBO could contribute to the progression of PD, by promoting or preventing neurodegeneration, thus being a potential target for treatments aiming at slowing down the progression of PD. The direct symptomatic impact of SIBO and its impact on symptomatic medication are also briefly discussed.

Keywords: Parkinson’s disease; SIBO; gut dysbiosis; gut–brain axis; microbiota; small intestinal bacterial overgrowth.

Publication types

  • Review

MeSH terms

  • Blind Loop Syndrome / complications
  • Dysbiosis / complications*
  • Gastrointestinal Microbiome*
  • Humans
  • Hydrogen / metabolism
  • Intestine, Small / microbiology*
  • Methane / metabolism
  • Parkinson Disease / microbiology*
  • Parkinson Disease / therapy


  • Hydrogen
  • Methane