Effect of daily consumption of a fermented milk containing Lacticaseibacillus paracasei strain Shirota (LcS) on stool consistency in U.S. adults with hard or lumpy Stools: a randomized controlled trial.

Abstract

Background: Lacticaseibacillus paracasei strain Shirota (LcS) has shown benefits for stool consistency in populations with certain bowel complaints (e.g., constipation), but data in a U.S. population is limited.

Objective: This study evaluated the effects of LcS on hard or lumpy stools (HLS) in an otherwise healthy population that generally represents the U.S. adult demographic.

Methods: In this randomized, controlled, open-label study, 50 participants (41 females, 9 males) with HLS in ≥25% of bowel movements (BMs) during a 14-day run-in period were randomized to receive either 80 mL fermented milk containing 8.0x10⁹ colony forming units LcS/mL for 28 days (active group) or no intervention (control group) followed by a 14-day post-intervention period. Bowel habits were recorded daily using a novel smartphone application. The primary endpoint was the presence of HLS in ≥25% of the participant rated BMs using the Bristol Stool Form Scale over the 28-day intervention. Secondary endpoints included the presence of reduced frequency of BMs with HLS from baseline, stool frequency, straining, incomplete evacuation, artificial intelligence-derived stool image scores, and Patient Assessment of Constipation Quality of Life (PAC-QOL) scores.

Results: The active group showed a significantly lower proportion of participants with HLS in ≥25% of BMs (odds ratio 0.34, 95% CI 0.14 - 0.80, p=0.014) along with a higher proportion of participants with a reduced frequency of BMs with HLS from baseline (odds ratio 2.86, 95% CI 1.03-7.92, p=0.043). The active group also demonstrated positive improvements in total PAC-QOL scores (p=0.003).

Conclusion: Daily consumption of LcS-containing fermented milk significantly reduced constipation symptoms and improved QOL in an otherwise generally healthy U.S. adult population with a history of intermittent BMs producing HLS. The intervention was well tolerated, with no serious adverse events related to the product, suggesting its safety and potential as a dietary strategy for managing constipation.

Clinical trial registration: This study was registered at ClinicalTrials.gov as NCT06014008 available at https://clinicaltrials.gov/study/NCT06014008.