Cedars-Sinai researchers have developed a novel nutritional formula, mBiota Elemental, a palatable elemental diet (PED) that reduces the abundance of key gut microbiome taxa and improves symptoms in patients with small intestinal bacterial overgrowth (SIBO) and intestinal methanogen overgrowth (IMO).

Intervention testing with mBiota Elemental showed normalized breath tests and relief of symptoms in the majority of participants, with no serious or severe adverse events.

Elemental diets are highly digestible nutritional formulas containing free amino acids, simple carbohydrates, minimal fat, and essential micronutrients. Designed to provide complete nutrition with minimal stimulation of the digestive system, elemental diets have been used in conditions such as Crohn's disease, eosinophilic esophagitis/gastroenteritis, and chronic pancreatitis.

Intestinal microbial overgrowth syndromes, including SIBO and IMO, involve abnormally high levels of coliform bacteria or methanogenic archaea in the gastrointestinal tract. Antibiotics remain the primary treatment, yet normalization occurs in only about half of SIBO cases and fewer in IMO. Recurrence is common, often requiring repeated antibiotic courses which can have deleterious effects on the overall microbiome.

Previous retrospective findings suggested that elemental diets might reduce microbial overgrowth, yet no prospective clinical trials had tested this in patients with SIBO or IMO. Use of elemental diets in practice has been limited by poor palatability, which affects adherence in both pediatric and adult populations.

In the study, "Effect, tolerability, and safety of exclusive palatable elemental diet in patients with intestinal microbial overgrowth," published in Clinical Gastroenterology and Hepatology, researchers conducted a prospective, open-label clinical trial to assess the effect, tolerability, and safety of a novel PED in adult subjects with SIBO and/or IMO.

A total of 30 adults with confirmed diagnoses of SIBO, IMO, or both based on lactulose breath tests were enrolled. All participants received a two-week course of mBiota Elemental PED, followed by a two-week period of regular food reintroduction.

Researchers used structured symptom questionnaires, daily visual analog scale ratings, stool image analysis through artificial intelligence, breath gas measurements, 16S rRNA gene sequencing of stool samples, and digital PCR analysis for Methanobrevibacter smithii. Body composition was measured with bioelectrical impedance, and blood tests were used to monitor electrolytes and glucose.

All 30 participants completed the two-week trial of mBiota Elemental. Breath test normalization occurred in 73% of subjects. Adequate global relief of symptoms was reported by 83%.

Significant reductions in exhaled methane and hydrogen levels were recorded, with average maximum methane decreasing from 41 to 12 parts per million (ppm) and hydrogen from 43 to 12 ppm. Fasting daily methane levels in subjects with IMO or IMO/SIBO dropped below 5 ppm by day five of the intervention.

Stool microbiome analysis revealed reduced relative abundance of key microbial groups, including Prevotella_9 and Fusobacterium, by the end of the trial. Digital PCR analysis showed that 92% of subjects with detectable

Methanobrevibacter smithii at baseline had reduced or undetectable levels by the end of the trial. Post‑PED, hydrogen production shifted from an early (small‑bowel) peak to a later (colonic) rise, indicating altered fermentation geography in the gut.

Symptom tracking showed significant improvements during the PED phase in bloating, distention, abdominal discomfort, constipation, and flatulence. Additional symptoms, including abdominal pain, fatigue, diarrhea, urgency, and brain fog, improved during the food reintroduction phase. Fasting electrolytes (sodium, potassium, chloride, bicarbonate) and glucose stayed within normal ranges throughout, addressing a common safety concern for elemental diets.

No serious or severe adverse events were reported. Mild side effects included diarrhea, cramps, nausea, fatigue, heartburn, belching, urgency, and transient hemorrhoidal bleeding. Subjects lost approximately 3 kg, driven mainly by reductions in total body fat and visceral fat.

Findings suggest a short-term course of mBiota Elemental may offer an effective non-antibiotic dietary approach for managing SIBO and IMO.

All participants completed the full course, an adherence rate that the authors attribute to the improved taste, smell, and texture of the formula, overcoming a long‑standing barrier to elemental‑diet use.

Palatability of the formula may improve the clinical utility of elemental diets for patients with microbial overgrowth syndromes. Further controlled trials are needed to evaluate long-term outcomes and underlying mechanisms.

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