TOPLINE:

Oral supplementation with the heat-treated probiotic derived from Bifidobacterium longum CECT 7347 for 8 weeks yielded a greater reduction in allergic rhinitis (AR) symptom scores than placebo in adults with moderate-to-severe AR, particularly in those taking multiple AR medications and those with polysensitization.

METHODOLOGY:

• Researchers conducted a randomized trial to evaluate whether daily supplementation with live B longum CECT 7347 (PRO) or its heat-treated postbiotic form (POST) improves quality of life in adults with AR.
• A total of 72 participants with a medical history of symptomatic moderate-to-severe AR and a positive immunoglobulin-E sensitization test result (mean age, 38.6 years; 82% women) were randomly assigned to receive placebo (250 mg maltodextrin; n = 22), PRO (2 × 10⁹ colony-forming units per day with maltodextrin; n = 17), or POST (2 × 10⁹ cells per day, equivalent to 20 mg/d, with maltodextrin; n = 25) as two capsules once daily for 8 weeks.
• The primary outcome was a change in the combined symptom and medication score (CSMS) after 8 weeks of intervention vs placebo; CSMS was calculated as the sum of the daily symptom score and daily medication score, with higher scores indicating a greater clinical burden of AR.

TAKEAWAY:

• At week 8, the POST group demonstrated a statistically significant improvement in CSMS from baseline compared with the placebo group, with a mean between-group difference of 0.60 points (95% CI, 0.09-1.12; P = .022).
• No statistically significant differences in CSMS or quality of life from baseline were observed in the PRO group vs the placebo group during the 8-week intervention period.
• Participants in the POST group showed a statistically significant reduction in mean daily symptom score from baseline compared with those in the placebo group (P = .048), with particularly pronounced reductions in those taking multiple medications for AR (P = .030), those using intranasal corticosteroids (P = .006), and those with polysensitization (P = .025).
• Thirteen participants reported experiencing adverse events; three withdrew from the study — one in the placebo group due to stomach discomfort and two in the POST group, with one withdrawal due to bloating and one due to diarrhea.

IN PRACTICE:

“These results suggest that improvements in clinical outcomes may occur even in the absence of detectable taxonomic changes in the gut microbiome, highlighting the importance of considering functional and host-mediated mechanisms when evaluating microbiome-targeted interventions,” the authors of the study wrote.

SOURCE:

Richard Day, with ADM Health & Wellness, London, England, was the corresponding author of the study, which was published online on April 28, 2026, in Allergy.

LIMITATIONS: 

The study’s single-center design, modest sample size, and unequal attrition — particularly in the PRO arm — reduced statistical power and precision. The cohort had 82% women, limiting the generalizability of the findings to the broader adult population. Heterogeneity in allergen sensitization and concomitant medications added variability, and the lack of nasal (local) sampling prevented mechanistic insight into mucosal responses and complicated the interpretation of the null systemic biomarker findings.

DISCLOSURES:

The study was funded by Centro para el Desarrollo Tecnológico Industrial and Archer Daniels Midland (ADM). All authors reported being employees of ADM. The authors reported having no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.