Benefits
Bowel-related quality of life scores
In a 6-week double-blind trial in 84 adults with IBS and diarrhea, one capsule a day at either of two doses raised the IBS quality of life score, the main outcome, more than placebo, and gut-specific anxiety also eased more. Weekly ratings of overall symptom relief did not differ from placebo. An AB-Biotics scientist was an author, and the company made the capsules.
Digestive comfort after a lactose challenge
In an 8-week trial in 48 adults with confirmed lactose intolerance (33 on the blend, 15 on placebo), the total symptom score after drinking lactose, the main outcome, fell more than on placebo, with less abdominal pain and gas. The hydrogen breath test did not differ between groups, so digestion of lactose itself was not shown to change.
Stress-related loose stools in healthy adults
In a 4-week placebo-controlled trial in 60 healthy Japanese adults who felt routine stress and had loose stools, the diarrhea section of a gut symptom questionnaire, part of the main outcome, improved more than on placebo, while the urgency, general loose stool, reflux, stomach and constipation items did not differ. All six authors worked for Kaneka.
Abdominal pain and stool form in a three-arm trial
In a 6-week, three-arm trial in 55 adults with IBS, response rates for quality of life were 50.0% on the blend alone, 68.4% with the antispasmodic alverine plus simethicone and 16.7% on placebo, with similar patterns for pain and stool form. The p-values compare all three groups at once, and the trial was registered after it ended.
Gut symptoms and gut barrier markers in endurance runners
In a 4-week crossover trial in 16 healthy runners, gut symptoms during a treadmill run, blood markers of gut permeability and stool bacteria did not differ from placebo. The run did not provoke enough symptoms to test a difference, so the result says little either way. The paper names only the species; the team's registry entry lists the i3.1 strains.
Mechanism of action
Gut lining permeability in cell culture
In a laboratory study, the blend reduced leakiness of a layer of human gut cells (Caco-2) that had been exposed to fluid released by gut biopsies from people with IBS, raised beta-actin and CYP1A1 gene activity and produced indole-3-lactic acid. AB-Biotics funded the work, and none of this has been measured in people taking the blend.
Inflammation signals in animal models
In two mouse models of colon inflammation, 1 billion CFU a day of the blend limited weight loss and lowered the inflammatory signals IL-6 and interferon-gamma compared with untreated mice. Mouse results do not show the same effect in people.
Gut bacteria and fermentation products
In a small uncontrolled study, stool volatile compounds shifted during 30 days of use, and in a trial in stressed adults, gains in a loose stool score tracked a rise in Faecalibacterium, a butyrate-producing genus. These are correlations and microbiota markers, not proof of how the blend works.
Clinical trials
Multicenter, randomized, double-blind, placebo-controlled, three-arm trial in Spain: one capsule a day of the 1:1:1 blend at a high dose (10 to 30 billion CFU) or low dose (3 to 6 billion CFU), or placebo, for 6 weeks; primary outcome IBS quality of life (IBS-QoL); enrolled 2010 to 2011, below the 33 per arm the power calculation targeted; no registry number found in the paper; AB-Biotics produced the capsules and randomization lists and Jordi Espadaler, an author, was affiliated with AB-Biotics; supported in part by Spain's Instituto de Salud Carlos III (Lorenzo-Zúñiga et al. 2014, World J Gastroenterol)
84 adults aged 20 to 70 with IBS with diarrhea (Rome III): 28 high dose, 27 low dose, 29 placebo.
After 6 weeks, IBS-QoL rose 18 and 22 points on the high and low doses versus 9 on placebo (P = 0.041 and P = 0.023), with no difference between doses. Gut-specific anxiety (Visceral Sensitivity Index) also improved more than on placebo at 6 weeks but not at 3 weeks. Overall symptom relief responders were 42% and 32% versus 25% on placebo, not a significant difference (P = 0.467). No adverse drug reactions were reported.
Randomized, placebo-controlled trial at Hospital Juárez de México with 2:1 allocation: i3.1 (3 billion CFU of the three strains once daily, per the registry) or maltodextrin placebo for 8 weeks; primary outcome the total symptom score after a 25 g lactose challenge; registered NCT04164394 in November 2019, about six months after enrollment began; one author, Jordi Espadaler Mazo, was from AB-Biotics (Kaneka Group); funding is not stated in the abstract (Cano-Contreras et al. 2022, J Clin Gastroenterol)
48 adults with lactose intolerance confirmed by hydrogen breath test and symptom score: 33 on i3.1, 15 on placebo.
The total symptom score after lactose fell by 5.11 points on i3.1 versus 1.00 on placebo (P < 0.001), with between-group differences for abdominal pain (P = 0.045) and flatulence (P = 0.004). The breath test area under the curve fell within the i3.1 group but did not differ between groups (P = 0.621). Adverse events were mild and similar in both groups.
Double-blind, placebo-controlled, parallel trial: one capsule a day with 1 billion CFU each of P. acidilactici KABP-021 (CECT7483) and L. plantarum KABP-022 (CECT7484) and KABP-023 (CECT7485), or placebo, for 4 weeks; primary outcome the Izumo abdominal symptom questionnaire; registered UMIN000041470; all six authors were Kaneka Corporation staff, the paper reports no specific grant and the authors declared no conflict of interest (Sato et al. 2022, Heliyon)
60 healthy Japanese adults aged 20 to 64 (34 men, 26 women) who felt routine stress and had loose stools with abdominal discomfort, without a diagnosed gut disorder; 30 per group, all completed.
Reflux, stomach and constipation items on the Izumo scale did not differ from placebo, nor did the urgency or loose stool items on their own. The stress-related diarrhea item (P < 0.001) and the total diarrhea score (P = 0.021) improved more than on placebo. Mental health scores on the SF-8 and work productivity measures also favored the probiotic. Adverse events were mild and judged unrelated.
Randomized, placebo-controlled pilot trial at Hospital Juárez de México: i3.1 alone, i3.1 plus alverine citrate 60 mg and simethicone 300 mg three times daily, or placebo, for 6 weeks; the registry gives i3.1 as 3 billion CFU once daily and disease-specific quality of life as the primary outcome; registered NCT04145856 in October 2019, after the trial ended; no AB-Biotics author is listed, and funding is not stated in the abstract (Barraza-Ortiz et al. 2021, Dig Dis)
55 adults with IBS recruited at a Mexico City hospital.
Response on the IBS-QoL questionnaire (intention to treat) was 50.0% with i3.1 alone, 68.4% with i3.1 plus the antispasmodic and 16.7% with placebo (P = 0.005 across the three groups). Abdominal pain response was 38.9%, 57.9% and 16.7% (P = 0.035), and stool consistency response 44.4%, 57.9% and 16.7% (P = 0.032). The abstract does not give pairwise comparisons of i3.1 alone with placebo.
Randomized, double-blind, placebo-controlled crossover trial at the University of Memphis: 4 weeks of a daily probiotic containing P. acidilactici and L. plantarum, or placebo, with treadmill runs at 27 °C; the abstract names only the species, and the team's registry entry, NCT05425329 (filed in 2022 after the study ended), lists the three i3.1 strains at 3 billion CFU a day with blood gut permeability markers as primary outcomes; the authors declared no competing interests (Lennon et al. 2024, Appl Physiol Nutr Metab)
16 healthy endurance runners randomized (17 enrolled in the registry).
Gut symptoms, gut permeability markers (intestinal fatty acid binding protein, lipopolysaccharide binding protein, zonulin), cytokines and stool microbiota did not differ from placebo, before or after the run. The run did not provoke enough gut symptoms to test a difference. Aspartate aminotransferase fell marginally on the probiotic only (p = 0.05). The probiotic was reported to be safe.
Double-blind, placebo-controlled trial registered NCT03542786 and sponsored by AB-Biotics: daily sachets of i3.1, i3.1 plus a fiber prebiotic, or placebo for 6 months plus 3 months off treatment, alongside stable antiretroviral therapy; primary outcomes safety and tolerability; the CFU dose is not given in the sections read; funded by the EU Horizon 2020 program and Spanish public grants; two authors, Jordi Espadaler-Mazo and Meritxell Aguiló, were full-time AB-Biotics employees (Blázquez-Bondia et al. 2022, Front Immunol)
71 adults with HIV-1 on stable antiretroviral therapy whose CD4 counts stayed below 500 cells/mm3, randomized 1:2:2 to placebo, probiotic or probiotic plus prebiotic. This is a disease population on drug treatment, cited here for safety context only.
Adverse events occurred in 53%, 33% and 55% of the placebo, probiotic and probiotic plus prebiotic groups, mostly mild flatulence, bloating and diarrhea. The probiotic alone had no effect on immune measures or stool microbiome composition. The prebiotic combination gave small rises in the CD4/CD8 ratio of uncertain clinical significance.