How Does a Palatable Elemental Diet Help Patients with Microbial Overgrowth?
Study: Fajardo, C., et al. (2026). 581 Effect of exclusive palatable elemental diet on systemic inflammation and gut microbiome in microbial overgrowth syndromes: Ad hoc analysis of a prospective trial. Gastroenterology. 170. S-2413.
Key Takeaways
This study looked at why mBIOTA may help patients with SIBO, IMO, or mixed microbial overgrowth.
Findings point to microbiome rebalancing, not reduced systemic inflammation, as the main mechanism of benefit.
mBIOTA reduced selected microbes linked to overgrowth while preserving overall microbiome diversity.
Methane-producing organisms decreased, which may be especially important for patients with IMO.
Elemental diet study design
Elemental diets have been used in several gastrointestinal conditions, including inflammatory disorders such as Crohn’s disease. But in microbial overgrowth syndromes such as small intestinal bacterial overgrowth (SIBO) and intestinal methanogen overgrowth (IMO), researchers are still working to understand how elemental diets help.
This study reviewed data from a previous clinical trial of the palatable elemental diet mBIOTA. Scientists reexamined stool microbiome samples from 30 participants with microbial overgrowth: some with SIBO, some with IMO, and some with both. Participants completed 14 days of an exclusive palatable elemental diet, followed by 14 days of follow-up after reintroducing solid food.
The goal was to understand the mechanism behind mBIOTA’s benefit. Specifically, researchers wanted to know whether improvement was driven by reduced systemic inflammation or by changes in the gut microbiome. To answer this, they used advanced metagenomic testing to study the microbiome and immunoassays to measure inflammatory markers in the blood. These markers were evaluated before the elemental diet, immediately after completing the diet, and two weeks after participants transitioned back to a regular diet.
Patient Outcomes
The findings point clearly toward microbiome modulation as the main mechanism of benefit. Inflammatory markers were within normal limits at baseline and did not meaningfully decrease after the elemental diet, with the exception of modest changes in two markers (IL-13 and CCL20). This suggests that, unlike inflammatory conditions such as Crohn’s disease or ulcerative colitis, microbial overgrowth syndromes may not be driven by high levels of systemic inflammation.
Instead, the strongest changes were seen in the microbiome. mBIOTA shifted specific microbial populations without broadly suppressing the entire gut microbiome. Overall microbiome richness and diversity were preserved, and many commensal bacteria (the microbes our gut normally works alongside) were restored after participants resumed a regular diet.
At the same time, some microbes associated with dysbiosis or overgrowth remained reduced even after patients returned to a regular diet. These included Methanobrevibacter smithii and Candida albicans. This is notable because M. smithii is a major methane-producing organism associated with intestinal methanogen overgrowth, while C. albicans is a fungal species that can be involved in fungal overgrowth under certain conditions. In contrast, the beneficial fungus Saccharomyces cerevisiae did not show significant changes.
Mechanims of Impact
Together, these findings suggest that mBIOTA may help patients with microbial overgrowth by rebalancing the microbiome rather than by quieting systemic inflammation. The diet appeared to reduce selected microbes linked to overgrowth while preserving broader microbiome diversity, a pattern that may help explain symptom improvement in patients with SIBO, IMO, or mixed microbial overgrowth.
Interested in learning more?
Watch the research team present at Digestive Disease Week 2026.
Read the publication by Fajardo, C., et al. (2026).