Fecal transplants offer brief relief from Parkinson’s motor symptoms

Fecal microbiota transplantation (FMT), a technique that uses processed stool from a healthy donor to help restore healthy bacteria in the gut, may provide a small, short-term improvement in daily motor activities for people with Parkinson’s disease, but current evidence does not show sustained benefits for overall motor function, nonmotor symptoms, or quality of life, a review study found.

“Current randomized evidence does not support a clear or sustained clinical benefit of FMT in [Parkinson’s disease],” the researchers concluded.

The study, “Efficacy and safety of fecal microbiota transplantation in Parkinson’s disease: a systematic review and meta-analysis of randomized controlled trials with GRADE assessment,” was published in Neurological Sciences.

Parkinson’s is caused by the progressive loss of dopamine-producing nerve cells in the brain. Dopamine is a chemical messenger that allows nerve cells to communicate and, among other functions, helps regulate movement. While the disease hallmarks are motor symptoms, such as tremor, muscle rigidity, and slowness of movement, patients also may experience nonmotor symptoms including cognitive changes, depression, sleep problems, and gastrointestinal symptoms.

Changes in the gastrointestinal tract may be involved in Parkinson’s years before movement symptoms appear. Constipation affects up to 80% of patients and may be an early symptom.

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April 3, 2026 News by Margarida Maia, PhD

Fecal transplants ease motor symptoms in early Parkinson’s: Study

Gut differences

Researchers have identified differences in the gut microbiota, the community of microorganisms living in the digestive tract, between people with and without Parkinson’s. An imbalance in these microorganisms, called dysbiosis, may affect communication along the gut-brain axis, a two-way network between the gut and the brain. However, it’s not clear whether dysbiosis contributes to Parkinson’s or results from it.

FMT is designed to modify the gut microbiota by introducing microorganisms from a healthy donor. It can be delivered via capsules, tubes that reach the intestine, or colonoscopy.

While animal experiments and small, uncontrolled studies have suggested that modifying the gut microbiota may lessen Parkinson’s symptoms, results from randomized trials have been mixed.

To clarify the evidence, a team led by researchers in Egypt conducted a systematic review and meta-analysis, statistically combining data from randomized controlled trials comparing FMT with a placebo or another control treatment.

Following a search across four medical databases through June 4, 2026, they identified seven trials involving 318 people with mild to moderate Parkinson’s. The studies were conducted in China, Finland, Belgium, Poland, and the U.S.

FMT was delivered via oral capsules, colonoscopy, or tubes inserted into the intestine.

Some participants received one transplant, while others received repeated doses via capsules or infusions. Control treatments varied, and follow-up ranged from 12 weeks to a year.

The main significant finding involved Part 2 of the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS), which assesses patients’ experiences with motor activities in daily life. After one month, FMT recipients showed a statistically significant reduction in the score compared with the placebo control group. Lower scores indicate fewer difficulties with daily motor activities.

Although results continued to favor FMT at three and six months, the differences were not statistically significant. By one year, there was no evidence of benefit.

FMT did not significantly ameliorate examiner-rated motor symptoms, measured by MDS-UPDRS Part 3, at any follow-up point. Overall scores and measures of motor complications also showed inconsistent, nonsignificant results.

A subgroup analysis suggested that repeated-dose FMT may improve off-medication motor scores at three months. However, the team noted that this finding came from a smaller subset of studies and requires confirmation.

Pooled results did not show significant improvements in nonmotor symptoms, quality of life, cognition, depression, or constipation.

Adverse events were mainly mild gastrointestinal problems. Most were mild and resolved on their own. The pooled analysis indicated that nausea was about twice as common with FMT as with a control treatment. Rates of diarrhea and bloating did not differ significantly between groups.

No major short-term safety signals emerged, but the studies followed participants for no longer than one year.