Prebiotic bar, eaten daily, helps to ease inflammation in patients’ gut

Pilot trial supports prebiotic fiber 'mixture' leading to healthier gut microbiome

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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An illustration of two young people, one drawing a digestive tract and its microbiome on the other.

Eating a tailored prebiotic fiber bar — meant to help nourish good bacteria in the gut — for 10 days boosted the abundance of anti-inflammatory bacteria in the microbiome of people with Parkinson’s disease, a proof-of-concept clinical trial reported.

These effects were associated with better intestinal health and protection against inflammation, supporting the “the scientific rationale for placebo-controlled trials using prebiotic fibers in PD [Parkinson’s disease] patients,” the researchers wrote.

Trial results were reported in “An open label, non-randomized study assessing a prebiotic fiber intervention in a small cohort of Parkinson’s disease participants,” published in the journal Nature Communications.

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Inflammation elevated in brains of newly diagnosed patients

Pilot trial tests 10 days of a dietary prebiotic bar mixture in 20 patients

The gut microbiome refers to the vast community of friendly bacteria, fungi, and viruses that colonize the gastrointestinal tract and help in its function. Its imbalance, known as gut dysbiosis, can promote inflammation and trigger or worsen certain health conditions.

Evidence of interaction across the gut-brain axis points to the gut microbiome, and particularly its imbalance, as one the many possible causes of Parkinson’s.

“It is well-established that the intestinal milieu can influence the brain, including neuroinflammation … and neurodegeneration,” the researchers wrote.

Patients carry a more pro-inflammatory gut microbiome that can cause inflammation, including in the brain, via various mechanisms. One such mechanism is linked to lower levels of short-chain fatty acids (SCFAs), fatty molecules that are essential for the maintenance of the intestinal barrier.

Low SCFA levels associate with what is known as a leaky gut, allowing for bacterial pro-inflammatory factors there to circulate in the blood and reach the brain, where they trigger neuroinflammation.

Prebiotics, a form of dietary fiber found in many vegetables and fruits, can stimulate the growth of healthy gut bacteria and raise SCFA levels.

A team led by researchers at Rush University Medical Center in Chicago conducted a small clinical trial (NCT04512599) to assess whether a prebiotic dietary intervention could correct the gut dysbiosis seen in Parkinson’s patients.

Before launching the trial, the researchers conducted a series of experiments, fermenting patients’ stool samples with different types of prebiotic fibers to identify those best capable of increasing SCFA levels. Prebiotics tested included resistant starch, rice bran, resistant maltodextrin, and inulin.

Since each fiber promoted the growth of a different set of beneficial bacteria, a tailored selection of fibers was incorporated into the trial’s dietary bar. It consisted of 30% resistant starch (raw potato starch), 30% resistant maltodextrin (Nutriose), 30% stabilized rice bran, and 10% agave branched inulin.

Two groups of Parkinson’s patients were enrolled: 10 newly diagnosed people not on any disease treatment and 10 others with more advanced disease and using levodopa and other medications.

Participants were instructed to eat one prebiotic bar in the morning for three days, and then one bar in the morning and one in afternoon for the following week, covering a total of 10 days.

At the end of treatment, results showed no worsening in patients’ gastrointestinal symptoms, including bloating and diarrhea, due to the prebiotic bar. Rather, patients with more advanced disease and on Parkinson’s medications reported an easing in these symptoms.

In addition, 55% of participants reported they were “highly likely” to continue consuming the prebiotic bar, 35% said they were “somewhat likely,” and the remaining 10% were “likely.” No patient responded as being “somewhat unlikely” or “unlikely” to continue with the bar.

These responses mirrored the intervention being both well tolerated and safe, meeting the trial’s main and secondary goals.

Higher levels of fatty molecules that prevent a ‘leaky gut’ reported

An exploratory analysis also linked the prebiotic intervention to a reduction in disease severity, as assessed with the Unified Parkinson’s Disease Rating Scale.

Analyses of patients’ stool samples showed that while the overall microbial community was not affected by the prebiotic intervention, the abundance of specific bacterial species changed: certain pro-inflammatory bacteria were reduced, and SCFA-producing species were increased.

This was accompanied by a reduction in “multiple biosynthetic pathways previously reported to be upregulated in PD patients,” the team wrote.

Blood SCFA levels significantly increased after the intervention. In turn, lower blood levels of zonulin, a marker of intestinal barrier dysfunction and inflammation, and stool levels of calprotectin, a marker of intestinal inflammation, were reported.

Data also showed that higher zonulin levels were linked to more pro-inflammatory bacteria and fewer SCFA-producing bacteria. More SCFA-producing bacteria were associated with lower blood levels of the pro-inflammatory molecule TNF-alpha.

Blood levels of neurofilament light chain, a marker of nerve cell damage, also were significantly reduced after the prebiotic intervention. This drop was seen mainly in newly diagnosed, untreated patients.

Overall, “this proof-of-concept study demonstrates that a SCFA-promoting prebiotic fiber mixture can be used to modulate the intestinal microbiota in PD patients (i.e., the approach is feasible) and that the prebiotic mixture is well-accepted, tolerated, and safe for use in PD patients,” the researchers wrote.

“Moreover, the prebiotic fiber mixture may have a clinical impact leading to reduced severity of motor and non-motor PD symptoms and improved gastrointestinal function,” they added.