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The Effects of Lactiplantibacillus plantarum 299v on Irritable Bowel Syndrome: A Systematic Review with Meta-analysis

This systematic review and meta-analysis of six randomized controlled trials demonstrates that the probiotic *Lactiplantibacillus plantarum* 299v significantly improves abdominal pain, bloating, flatulence, and global symptoms in adults with irritable bowel syndrome, although it shows no significant effect on constipation.

Original authors: Viviana Fara Brindicci, Vanessa Nadia Dargenio, Giovanni La Grasta, Stefania Paola Castellaneta, Federico Schettini, Ruggiero Francavilla, Fernanda Cristofori

Published 2026-08-04

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CC BY 4.0

Original authors: Viviana Fara Brindicci, Vanessa Nadia Dargenio, Giovanni La Grasta, Stefania Paola Castellaneta, Federico Schettini, Ruggiero Francavilla, Fernanda Cristofori

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine your gut as a bustling, noisy city. Inside this city, trillions of tiny microbes live and work, keeping the streets clean and the traffic flowing. Sometimes, however, the city gets into a state of chaos. The traffic lights go haywire, the streets get clogged, and the residents start complaining about constant construction noise and pain. This is what happens in a condition called Irritable Bowel Syndrome (IBS). It's not a disease with a single broken part, but rather a mix-up in how the gut talks to the brain, how the muscles move, and how the microbial community is balanced. Because the "microbial city" is so important, scientists have started looking at probiotics—friendly bacteria that act like a specialized repair crew—to see if they can calm the chaos and restore order. But with thousands of different bacterial strains out there, it's hard to know which one is the right foreman for the job.

This paper is a deep dive into one specific repair crew: a friendly bacterium called Lactiplantibacillus plantarum 299v. The researchers didn't just guess; they gathered every single high-quality study (called Randomized Controlled Trials) that tested this specific strain against a fake treatment (placebo) in adults with IBS. Think of it as a referee reviewing game tapes from six different matches to see if this specific player actually helps the team win. The paper found that this bacterial strain is a star player for certain symptoms. It significantly reduced the "noise" of abdominal pain, making it less severe and less frequent, and it helped clear up the "traffic jams" of bloating and gas. The repair crew was so effective that patients were nearly five times more likely to feel better than those who took the placebo. However, the paper also found that this specific crew isn't a magic wand for everything; it didn't show any special ability to fix constipation. While the results are promising, the researchers note that the "games" they watched were played on different fields with different rules, so while the strain looks like a strong candidate for helping with pain and bloating, more research is needed to understand exactly how diet and other factors might change its performance.

Technical Summary: The Effects of Lactiplantibacillus plantarum 299v on Irritable Bowel Syndrome

Problem Statement
Irritable Bowel Syndrome (IBS) is a multifactorial functional disorder involving gut-brain axis dysregulation, visceral hypersensitivity, and gut microbiota alterations. While probiotics are increasingly considered therapeutic strategies, current guidelines (e.g., ESPGHAN/NASPGHAN) offer only weak or conditional recommendations due to low-to-moderate certainty evidence and a lack of strain-specific data. Although Lactiplantibacillus plantarum 299v (DSM 9843) possesses documented biological properties—such as enhanced intestinal adhesion, immunomodulation, and gut barrier reinforcement—a comprehensive, systematic appraisal of its efficacy in IBS was lacking. This study aimed to fill that gap by evaluating the clinical effects of L. plantarum 299v in patients with confirmed IBS.

Methodology
The authors conducted a systematic review and meta-analysis following Cochrane Handbook and PRISMA 2020 guidelines, registered in PROSPERO (CRD420261322875).

Data Sources: PubMed/MEDLINE, Embase, Scopus, and Cochrane Central Register of Controlled Trials were searched up to January 2026.
Eligibility: The review included randomized, double-blind, placebo-controlled trials (RCTs) involving adult patients with confirmed IBS. The intervention was single-strain L. plantarum 299v (DSM 9843). Multi-strain formulations and non-randomized studies were excluded.
Outcomes: Primary outcomes included changes in abdominal pain scores, severity, daily frequency, improvement rates, and global symptom improvement. Secondary outcomes covered bloating, flatulence, constipation, and safety.
Analysis: A random-effects model (DerSimonian and Laird) was used to pool data. Continuous outcomes were expressed as Standardized Mean Differences (SMD), and dichotomous outcomes as Relative Risk (RR). Heterogeneity was assessed using Cochran's Q and $I^2$ statistics. The GRADE framework was applied to assess evidence certainty.

Key Contributions

Strain-Specific Focus: Unlike broader probiotic reviews, this study isolates L. plantarum 299v, providing a targeted evaluation of a specific strain with a known biological profile (mannose-dependent adhesion, mucin upregulation, and anti-inflammatory cytokine modulation).
Mechanistic Context: The review integrates a narrative review of the strain's biological characteristics (resistance to GI transit, immunomodulation via IL-10 upregulation, and tight junction protein reinforcement) to contextualize clinical findings.
Dietary Interaction Hypothesis: The analysis highlights a potential diet-dependent response, noting that efficacy may vary based on patient dietary habits, specifically citing one included study (Ducrotté et al.) which reported greater abdominal pain relief in vegetarian patients compared to non-vegetarians. This suggests a need for future research into combined probiotic-dietary interventions.

Results
Six RCTs involving 527 adult participants were included.

Abdominal Pain: L. plantarum 299v significantly reduced abdominal pain scores (SMD = −2.16; $p=0.003$ ), pain severity (SMD = −0.39; $p=0.005$ ), and daily pain frequency (SMD = −0.66; $p=0.0004$ ) compared to placebo. The rate of pain improvement was significantly higher in the probiotic group (RR = 4.83; $p=0.0007$ ).
Bloating/Flatulence: The probiotic group showed a significantly higher improvement rate for bloating/flatulence compared to placebo (RR = 1.96; $p=0.03$ ).
Global Symptoms: Overall symptom improvement was significantly higher in the probiotic group (RR = 4.69; $p=0.010$ ). Sensitivity analysis excluding one outlier study increased the effect size (RR = 8.54) and eliminated heterogeneity ( $I^2=0\%$ ).
Constipation: No statistically significant difference was observed between the probiotic and placebo groups regarding constipation improvement (RR = 1.39; $p=0.66$ ).
Safety: Adverse events were rare and mild, indicating a good safety profile.
Heterogeneity: Substantial heterogeneity was observed in several outcomes (e.g., $I^2$ up to 94% for pain scores), attributed to variations in dosage (6×10⁹ to 5×10¹⁰ CFU), treatment duration (4–8 weeks), diagnostic criteria, and patient dietary patterns.

Significance and Claims
The authors conclude that meta-analytic evidence supports the capacity of L. plantarum 299v to relieve abdominal pain, bloating, flatulence, and general symptoms in adults with IBS, while showing no significant effect on constipation. The authors note that due to notable heterogeneity, the results should be interpreted as "hypothesis-generating rather than confirmatory" specifically regarding the consistency of the treatment effect across future studies, rather than the efficacy itself.

The paper asserts that while L. plantarum 299v offers clinically relevant benefits for pain and bloating, the current evidence warrants a "conditional recommendation" for its use as an additional treatment. The authors emphasize that future research must address the interaction between probiotic supplementation and dietary protocols (such as low-FODMAP diets) and standardize outcome measures to reduce variability. They explicitly state that no studies have yet assessed the combined effects of L. plantarum 299v with specific dietary interventions, identifying this as a critical area for future investigation.

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