Recent clinical trial data published in the journal Microorganisms reveals that daily supplementation with the probiotic strain Lacticaseibacillus rhamnosus CRL 1505 reduces the incidence and duration of upper respiratory tract infections (URTIs) in healthy adults. According to researchers from Sacco Srl, the Hospital Universitario de Elche, the Catholic University of Murcia, and CERELA-CONICET, the randomized, double-blind study addresses a significant knowledge gap by extending documented immune health benefits beyond pediatric populations.
Clinical Trial Findings on Adult Respiratory Health
The study followed 140 healthy adults aged 18 to 65 over a 12-week intervention period, with an additional four-week follow-up. Participants received either 1 billion colony-forming units (CFUs) per day of L. rhamnosus CRL 1505 or a placebo. Out of the 140 enrollees, 122 completed the protocol.
According to the published data, participants taking the probiotic experienced a 15.5% lower proportion of two or more URTI episodes after 16 weeks compared to the placebo group. For participants experiencing three or more infections, the reduction was 12.7%. Total URTI episodes also dropped significantly, with 53 recorded cases in the probiotic group versus 78 in the placebo group. Furthermore, the L. rhamnosus CRL 1505 group gained a 2.9% higher rate of URTI-free time.
Did you know? Lacticaseibacillus rhamnosus CRL 1505 is backed by more than 50 scientific publications, making it one of the most thoroughly studied probiotic strains for immune support across different age groups.
Expanding Probiotic Research Beyond Pediatrics
Valentina Taverniti, microbes & health R&D leader at Sacco S.r.l. and lead author of the paper, noted that the trial successfully broadens the clinical understanding of the strain. “New clinical evidence now extends its documented benefits beyond pediatric populations, demonstrating a reduction in upper respiratory tract infections in healthy adults, particularly those prone to recurrent episodes,” Taverniti stated.
The research carries distinct clinical relevance because URTIs frequently act as physiological triggers for exacerbations in chronic respiratory conditions. By strengthening the scientific foundation of CRL 1505, the findings offer new pathways for researchers investigating immune support strategies across a person’s lifespan.
Pro Tip: When evaluating probiotic supplements for immune health, look for specific, clinically tested strains—such as L. rhamnosus CRL 1505—rather than generic species labels, as health benefits are strain-specific.
Biomarkers and Future Research Directions
Despite the clear reduction in clinical infection rates, the trial recorded no significant differences between the groups regarding salivary IgA levels. Researchers observed that salivary IgA actually decreased in both cohorts over the 12 weeks of supplementation, indicating that the observed clinical protection operates through mechanisms outside of changes in this specific mucosal antibody.
Funding for the study was provided by Sacco S.R.L., and the bacterial strain belongs to the culture collection maintained by CERELA-CONICET in Argentina. Authors from the multi-institutional team emphasize that future studies should build upon these adult-focused results to refine preventive care models for respiratory health.
Frequently Asked Questions
What is Lacticaseibacillus rhamnosus CRL 1505?
It is a specific probiotic strain researched extensively for its effects on the immune system, originally isolated and maintained in the CERELA-CONICET culture collection.
How many CFUs were used in the adult URTI study?
Participants in the clinical trial received a daily dose of 1 billion CFUs for 12 weeks.
Did the probiotic completely prevent upper respiratory infections?
No, but the probiotic group experienced fewer total episodes, lower rates of recurrent infections, and more infection-free time compared to the placebo group.
Who funded the research published in Microorganisms?
The study was funded by Sacco S.R.L., with collaborative input from academic and clinical researchers in Italy, Spain, and Argentina.
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