The Tokai University School of Medicine assessed 24 Japanese patients with indigestion (functional dyspepsia) alongside 21 age- and gender-matched healthy controls to determine the effect of probiotics on gut microbiota.
Patients suffering from indigestion were treated with the probiotic strain Lactobacillus gasseri OLL2716 (LG21) in the form of 118g of yogurt daily for 12 weeks. They were then put on an overnight fast, after which their gastric fluid was sampled and comparatively analysed against that of the healthy controls.
Bacterial composition analysis found that the gastric fluid microbiota in the indigestion patients had "a Bacteroidetes > Proteobacteria abundance and an absence of Acidobacteria", while the gastric fluid microbiota in the healthy controls had a "Bacteroidetes < Proteobacteria abundance and the presence of Acidobacteria".
Probiotic therapy was shown to alter the composition of the gastric fluid microbiota in the indigestion patients to be on par with that of the healthy controls.
To this end, probiotics "appeared effective in the treatment of functional dyspepsia through the normalisation of gastric microbiota".
Effects on bile
Before the treatment period, median bile acid concentration was considerably greater in those with indigestion than in the healthy controls.
This was due to bile acid reflux into the stomach during gastric motility, as bile acids in the indigestion patients were not sufficiently evacuated from the stomach (as they normally are in healthy individuals).
The study found that after the 12-week treatment period, the ratio of gastric fluid samples that contained detectable bile acids was still significantly higher among the indigestion patients than the healthy controls.
This meant that the probiotic "yogurt treatment exerted no significant effects on the level of bile acids" in those suffering from indigestion.
The study hypothesised that probiotics could be an effective treatment for indigestion via the reduction of Escherichia / Shigella, a major source of toxic lipopolysaccharides in the upper gastrointestinal tract.
Probiotics was also considered a viable treatment for the restoration of gastric microbiota change.
The study concluded that "probiotics appear effective in the treatment of functional dyspepsia through the normalisation of gastric microbiota", but acknowledged its limitations, such as the relatively small number of samples, as well as the lack of post-treatment samples from the healthy controls.
Source: BMJ Open Gastroenterology
"Alteration in the gastric microbiota and its restoration by probiotics in patients with functional dyspepsia"
Authors: Muneki Igarashi, et al.