Study: L. acidophilus Outperforms Other Probiotics for IBS Abdominal Pain Relief
Posted by The CodonRX Science Team on May 12th 2026
Most probiotic studies test one strain against placebo. This one went further. A 2020 randomized controlled trial published in Nutrients by Martoni, Srivastava, and Leyer put L. acidophilus head-to-head against another probiotic — B. lactis — and placebo, tracking pain relief response rates over 42 days in IBS patients. The results established a clear hierarchy, with L. acidophilus outperforming both.
What Did the Trial Find?
Participants were assigned to one of three groups over 42 days: placebo, B. lactis, or L. acidophilus. Researchers tracked responder rates — the proportion of patients who achieved meaningful abdominal pain relief by the end of the trial.
The results:
- Placebo: 15.6% responder rate
- B. lactis: 28.2% responder rate (p = 0.031 vs. placebo)
- L. acidophilus: 52.3% responder rate (p < 0.001 vs. placebo; p = 0.001 vs. B. lactis)
L. acidophilus demonstrated the highest and most consistent response rate for relieving abdominal pain across the full 42-day trial period.
Why Does the Three-Arm Design Matter?
Comparing a probiotic only against placebo tells you whether it does something — not how it stacks up against alternatives. This trial's three-arm design adds meaningful comparative data: it shows that not all probiotics produce the same result in IBS patients. B. lactis was statistically better than placebo. L. acidophilus was statistically better than both. The gap between L. acidophilus and B. lactis — 52.3% vs. 28.2% — is nearly as large as the gap between B. lactis and placebo. Probiotic strain selection matters.
What Does a Responder Rate Tell You?
A responder rate measures the proportion of patients who achieved a clinically meaningful reduction in abdominal pain — not just a statistical shift in group averages. It asks how many people actually felt better, which is a more patient-relevant measure than a mean change in score. A 52.3% responder rate means more than half of IBS patients in the L. acidophilus arm reported meaningful pain relief within 42 days of starting treatment.
Study: Martoni, Srivastava & Leyer (2020)
- Published in: Nutrients, 12(2):363
- Design: Three-arm RCT — placebo vs. B. lactis vs. L. acidophilus over 42 days
- Results: L. acidophilus 52.3% · B. lactis 28.2% · Placebo 15.6%
- Statistical significance: L. acidophilus vs. placebo p < 0.001 · L. acidophilus vs. B. lactis p = 0.001
- What it means: L. acidophilus produced the highest and most consistent abdominal pain relief response rate in IBS patients across the full trial
CodonRX® is designed to go further. See what it can do for your gut.
Try CodonRX® — $85 30-day supply · Patented NCK2025™ · Made in the USA