Scientists discovered that people with Parkinson’s disease who haven’t started treatment yet have different types of bacteria in their gut compared to healthy people. Researchers studied stool samples from 49 patients with early Parkinson’s disease and 34 healthy people from Croatia. While the total amount of different bacteria was similar between groups, certain bacterial types were more or less common in Parkinson’s patients. These findings suggest that gut bacteria changes might be connected to Parkinson’s disease from the very beginning, even before medications are started. This discovery could help scientists better understand how the disease develops and potentially lead to new treatments in the future.

The Quick Take

  • What they studied: Whether people with untreated Parkinson’s disease have different gut bacteria compared to healthy people
  • Who participated: 49 people with newly diagnosed Parkinson’s disease who hadn’t started medication yet, and 34 healthy people of similar age, diet, and lifestyle from Croatia
  • Key finding: While the overall variety of gut bacteria was the same, certain bacterial species were more common in Parkinson’s patients (like Bacteroides types) while others were less common (like Alistipes and Dialister), suggesting early changes in the bacterial community
  • What it means for you: This research suggests gut bacteria may play a role in Parkinson’s disease from the start, but it’s too early to make any changes to diet or treatment based on this finding alone. More research is needed to understand if changing gut bacteria could help prevent or treat the disease

The Research Details

Researchers collected stool samples from two groups of people: those with newly diagnosed Parkinson’s disease who hadn’t started any medications, and healthy people matched for age, diet, and lifestyle. They used a special DNA test (called 16S rRNA gene sequencing) to identify and count all the different bacteria living in each person’s gut. This test is like taking a census of the bacterial community—it tells scientists which types of bacteria are present and how many of each type there are.

The researchers then compared the bacterial communities between the two groups to see if there were any differences. They looked at two main things: first, whether the total variety of bacteria was different (like comparing whether one neighborhood has more types of people than another), and second, whether specific bacterial types were more or less common between groups (like comparing whether one neighborhood has more doctors and fewer teachers than another).

This type of study is called a cross-sectional comparison because it takes a snapshot of both groups at one point in time and compares them, rather than following people over time.

Studying people with Parkinson’s disease before they start medication is important because it helps scientists see what the gut bacteria look like at the very beginning of the disease. Previous studies looked at people already taking Parkinson’s medications, which can change the bacteria. By studying untreated patients, researchers can tell whether the bacterial changes are part of the disease itself or caused by the medicines. This is like looking at a crime scene before anyone cleans it up—you get a clearer picture of what actually happened.

This study has several strengths: the researchers carefully matched the healthy control group to the Parkinson’s patients by diet and lifestyle, which helps ensure any differences are due to the disease rather than eating habits. The sample size of 83 people is reasonable for this type of study. However, the study only included people from Croatia, so the results might not apply to all populations. The study is also a snapshot in time rather than following people over years, so it can’t prove that bacteria changes cause Parkinson’s or how they change as the disease progresses. The findings need to be confirmed by other research teams before drawing strong conclusions.

What the Results Show

The researchers found that people with untreated Parkinson’s disease had the same overall variety of gut bacteria as healthy people—imagine two gardens with the same number of plant species but arranged differently. However, when they looked at specific bacterial types, they found important differences.

Three types of Bacteroides bacteria (B. fluxus, B. interstinalis, and B. eggerthii) and one type called Dielma fastidiosa were more common in Parkinson’s patients. At the same time, three other bacterial groups (Alistipes, Barnesiella, and Dialister) were less common in Parkinson’s patients compared to healthy people. Think of it like a neighborhood where some businesses are booming while others are struggling.

These specific changes in bacterial types, even though the total variety stayed the same, suggest that something about Parkinson’s disease affects which bacteria thrive in the gut. The researchers call this ‘dysbiosis,’ which is a fancy word for an imbalance in the bacterial community.

The fact that overall bacterial diversity was preserved (meaning the total number of different types was similar) is interesting because it suggests the disease doesn’t simply kill off bacteria or reduce variety. Instead, it appears to shift which types of bacteria are winning and losing in the gut environment. This is an important distinction because it suggests the gut environment in Parkinson’s disease is still diverse but reorganized in specific ways.

Earlier studies showed that people with Parkinson’s disease who were already taking medications had different gut bacteria than healthy people. This new study is important because it shows that some of these bacterial changes exist even before treatment starts. This suggests the bacteria changes might be part of the disease process itself, not just a side effect of the medications. However, scientists still don’t know if these bacterial changes help cause Parkinson’s disease or if the disease causes the bacterial changes.

This study has several important limitations to keep in mind. First, it only included people from Croatia, so the results might be different in other countries or ethnic groups. Second, it’s a one-time snapshot rather than following people over time, so researchers can’t tell how the bacteria change as Parkinson’s progresses or whether these bacterial changes predict who will develop the disease. Third, the study can’t prove that the bacterial changes cause Parkinson’s disease—it only shows they’re associated with it. Finally, the study is relatively small with 83 people total, so larger studies are needed to confirm these findings.

The Bottom Line

Based on this research alone, there are no specific dietary or lifestyle changes recommended for Parkinson’s patients or those at risk. The findings are interesting and suggest gut bacteria may be involved in Parkinson’s disease, but much more research is needed. People with Parkinson’s disease should continue following their doctor’s treatment recommendations. Future research might eventually lead to new treatments targeting gut bacteria, but that’s not yet available.

This research is most relevant to people with Parkinson’s disease, their families, and healthcare providers treating Parkinson’s. Scientists studying the disease should also pay attention to these findings. People worried about developing Parkinson’s disease might find this interesting, but it doesn’t yet provide actionable information for prevention. Anyone considering major dietary changes based on gut bacteria should talk to their doctor first.

This is early-stage research, so don’t expect immediate changes in how Parkinson’s is treated. Scientists will need to do follow-up studies over the next several years to understand whether these bacterial changes are important and whether modifying them could help patients. If this research direction proves promising, it might take 5-10 years before new treatments based on these findings become available.

Want to Apply This Research?

  • Users with Parkinson’s disease could track digestive symptoms (bloating, constipation, diarrhea) weekly using a simple 1-5 scale, since gut bacteria changes may affect digestion. This creates a baseline for future comparison if gut-targeted treatments become available.
  • While waiting for more research, users could maintain a food diary noting which foods seem to affect their digestive comfort. This helps identify personal patterns and provides data to share with healthcare providers. Include notes on energy levels and symptom severity to look for connections.
  • Set up monthly check-ins to review digestive patterns and any changes in Parkinson’s symptoms. This long-term tracking will be valuable if future research suggests specific dietary interventions, as users will have baseline data to compare against. Share patterns with your healthcare team during regular appointments.

This research is preliminary and does not provide medical advice. The findings show an association between gut bacteria changes and Parkinson’s disease but do not prove that bacteria changes cause the disease. People with Parkinson’s disease should continue following their doctor’s treatment plan and not make changes based solely on this study. Anyone considering dietary changes or supplements to modify gut bacteria should discuss this with their healthcare provider first, especially those taking Parkinson’s medications, as some changes could interfere with treatment. This article is for educational purposes and should not replace professional medical advice.