Novel Probiotic Reduces Recurrent RTIs in Adults, Opening New Product Development Avenues

London, United Kingdom — 23 July 2026

New clinical research highlights the efficacy of daily supplementation with Lacticaseibacillus rhamnosus CRL 1505 in reducing recurrent respiratory tract infections (RTIs) among healthy adults. A randomised, double-blind, placebo-controlled trial observed that individuals receiving the probiotic experienced a significant reduction in both the recurrence rate and overall number of upper RTIs compared to the placebo group. This positions CRL 1505 as a strong candidate for immune health formulations aimed at the adult market, extending its previously established benefits in children.

The study also noted that the probiotic group maintained longer intervals between infection episodes and demonstrated a reduced dependency on over-the-counter medications for symptom management. While these tangible benefits were observed, the trial did not identify significant differences in salivary IgA levels or the severity of individual infection episodes between the groups. This suggests the probiotic's mechanism may primarily involve preventing recurrent infections rather than modulating acute phase immune markers or symptom severity directly. The findings are particularly relevant for manufacturers seeking to differentiate immune support products in a crowded market.

The expansion of CRL 1505's evidence base from paediatric to adult populations is a critical development. It allows brand owners to develop new product lines or reformulate existing ones to target a broader demographic with a scientifically backed ingredient. This probiotic strain could become a core component of daily immune maintenance supplements, moving away from purely seasonal or acute use cases. The commercial implication is a potential increase in average order value and customer lifetime value through continuous daily purchase cycles.

What this means for United Kingdom

UK brand owners should assess their current immune support portfolios for reformulation opportunities with Lacticaseibacillus rhamnosus CRL 1505. The specific adult efficacy data supports premium positioning, enabling higher retail price points and improved margins. Compliance teams must ensure all marketing claims strictly adhere to FSA and EFSA guidance, focusing on 'reduces recurrence' rather than 'prevents' RTIs. The Boots and Holland & Barrett retail channels represent significant growth opportunities for new product launches leveraging this data, especially as consumer demand for year-round immunity solutions climbs. Procurement leads should evaluate current ingredient supplier capabilities and secure favourable MOQs and lead times for this specific strain.

This research provides a robust platform for marketing claims focused on 'daily immune resilience' and 'sustaining respiratory health'. Brands can leverage these findings to create direct-to-consumer campaigns highlighting sustained wellness rather than reactive treatment. The cost-benefit analysis for consumers shows promise, with reduced over-the-counter medication use potentially offsetting supplement costs, providing a stronger value proposition.

Brand owners increasingly rely on contract-manufacturing partners such as Supplement Factory to navigate these requirements.