Multispecies Probiotic Trial Tests a Gut-Liver Strategy in MASLD With Obesity
A randomized clinical trial from the University of Bari set out to test a simple idea with broad metabolic consequences: whether a daily multispecies probiotic can shift the gut environment enough to improve liver steatosis, inflammatory markers, gastrointestinal symptoms, and cardiometabolic risk in adults with metabolic-associated steatotic liver disease and obesity. The protocol, posted as GUT-MET 2026, enrolled 56 adults and followed them for 6 months.
The study did not ask a narrow question. It asked whether changing the intestinal ecosystem might alter the clinical course of a disorder now recognized as a systemic metabolic disease rather than an isolated hepatic one.
A 6-Month Randomized Comparison of Probiotic Plus Lifestyle Advice Versus Lifestyle Advice Alone
Investigators randomized eligible patients in a 1:1 ratio to either a probiotic arm or a control arm. Both groups received dietary planning and physical activity recommendations designed for metabolic health, while the intervention arm received an additional daily dose of probiotic powder for 6 months. The design was parallel, randomized, and open label, with no masking.
The product itself was a carefully constructed blend, not a single-strain supplement. Each 3-gram sachet contained a total of 7.5 × 10⁹ colony-forming units drawn from multiple organisms, including Lactobacillus acidophilus W37, Lactobacillus brevis W63, Lactobacillus casei W56, Lactobacillus salivarius W24, Bifidobacterium bifidum W23, Bifidobacterium lactis W52 and W51, and Lactococcus lactis W19 and W58. The powder was dissolved in water and taken on an empty stomach before breakfast after a brief activation period.
One sentence captures the biological ambition of the protocol: the intervention was designed to act on the gut microbiota as a lever for systemic metabolic change.
Liver Steatosis, Anthropometrics, and Symptom Burden Were Tracked Side by Side
The trial measured far more than body weight. At baseline and at 6 months, researchers recorded body weight, height, body mass index, waist circumference, and hip circumference. These are basic numbers, but in MASLD they matter because central adiposity tracks with insulin resistance, hepatic fat accumulation, and chronic low-grade inflammation.
Liver status was followed with ultrasound echography at both time points, and the imaging was performed by an experienced radiologist who remained blinded to group assignment. That decision matters because ultrasound grading can be influenced by expectation, especially in a study that was otherwise open label.
Gastrointestinal symptoms were assessed using the validated Gastrointestinal Symptom Rating Scale, while diet quality was measured with the 14-item Mediterranean Diet Adherence Screener. Physical activity and sedentary behavior were captured using the short form of the International Physical Activity Questionnaire. The trial therefore connected symptom burden, eating behavior, activity patterns, and hepatic imaging in one framework instead of treating each domain as isolated data.
Blood and Stool Sampling Turned the Trial Into a Metabolic and Microbiome Study
The laboratory component was extensive. Fasting venous blood was collected in the morning after an overnight fast, and serum and plasma were frozen for later analysis. Plasma was sent to an external certified laboratory for glycemic and lipid profiling, as well as liver biomarkers and enzymatic activity. Serum was used to quantify inflammatory, anti-inflammatory, and oxidative stress markers using enzyme-linked immunosorbent assay methods in duplicate.
Stool collection was equally deliberate. Patients collected samples at home using sterile kits, and the material was transferred for immediate freezing before later DNA extraction and 16S rRNA gene amplicon sequencing. That sequencing pipeline was handled at the Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna, allowing the team to generate high-resolution taxonomic data from the fecal microbiota.
The logic behind all of this is straightforward even if the biology is not. In MASLD, excess energy intake, insulin resistance, microbial dysbiosis, and inflammatory signaling can reinforce one another. A probiotic could, in theory, alter bile acid handling, gut barrier function, microbial composition, and endotoxin exposure, with downstream effects on liver fat and metabolic biomarkers. Whether those pathways are modified enough to matter clinically is the question this study was built to answer.
Eligibility Focused on Adults With Metabolic Disease and Active Gastrointestinal Symptoms
Enrollment was restricted to adults 18 to 65 years old who had MASLD, a body mass index of at least 25 kg/m², and gastrointestinal symptoms. Patients could not have taken antibiotics or probiotics in the previous three months. Pregnant or lactating women were excluded, as were patients with severe cardiovascular, renal, or hepatic disease.
That selection strategy points to a specific clinical population: adults with metabolic disease who were stable enough to participate in a lifestyle plus supplement trial, but symptomatic enough for gastrointestinal outcomes to remain relevant. The result is a cohort likely enriched for the kind of patients clinicians commonly see in metabolic clinics rather than a narrowly selected liver-only population.
The Trial Was Built to Detect Whether Microbiome Shifts Parallel Metabolic Improvement
Primary outcomes centered on mean changes from baseline in body mass index, waist circumference, hip circumference, and fasting plasma glucose at 6 months. Secondary measures included glycemic and lipid profiles, liver biomarkers, ultrasound steatosis grading, gastrointestinal symptoms, diet adherence, physical activity, inflammation, anti-inflammatory signaling, oxidative stress, and gut microbial composition.
This matters because MASLD rarely moves on a single axis. If a probiotic exerts a meaningful effect, it would not be surprising to see several domains change together rather than one biomarker acting alone. Reductions in central adiposity, for example, would fit with improved insulin sensitivity and lower hepatic fat flux; changes in stool microbiota could provide mechanistic support for those clinical shifts.
Still, the study’s design also places real constraints on interpretation. The open-label format leaves room for behavioral effects, especially when both groups are advised to modify diet and physical activity. The sample size was modest, and the record provided no posted results, so the most responsible reading is methodological rather than promotional.
What This Trial Adds Before Results Are Even Posted
Completed on July 30, 2026, this trial joins a growing body of work treating MASLD as a disorder at the intersection of hepatology, metabolism, and the gut microbiome. Its value lies not in a headline effect size, which has not been posted here, but in the way it maps the biological terrain: liver ultrasound, symptom scoring, fasting biomarkers, inflammatory mediators, and 16S sequencing all in one protocol.
If a probiotic proves useful in this setting, the benefit would likely come from coordinated small shifts rather than a single dramatic signal. If it does not, the same dataset can still clarify whether microbiome manipulation is enough when diet and activity advice are already in place. The unanswered practical question is whether an oral microbial supplement can produce measurable clinical change beyond standard lifestyle counseling in adults with obesity and MASLD.