Efficacy and safety of the probiotic Lactobacillus paracasei LP-33 in allergic rhinitis: a double-blind, randomized, placebo-controlled trial (GA2LEN Study)

Eur J Clin Nutr. 2014 May;68(5):602-7. doi: 10.1038/ejcn.2014.13. Epub 2014 Feb 26.


Background/objectives: An imbalance between Th1 and Th2 cells is involved in allergic rhinitis (AR) that may be improved by probiotics. To test the efficacy of the probiotic Lactobacillus paracasei subsp. paracasei LP-33, a double-blind, placebo-controlled, randomized trial was carried out in patients with AR to grass pollen treated with loratadine and presenting altered quality of life.

Subjects/methods: Subjects with persistent AR, symptomatic during the grass pollen season, and a positive skin test or specific immunoglobulin E to grass pollens were included by general practitioners (GPs). All received loratadine for 5 weeks. The primary end point was the improvement in Rhinitis Quality of Life (RQLQ) global score at the fifth week of LP-33 consumption compared with placebo (in addition to loratadine). Secondary end points included nasal and ocular symptoms (individual and total symptom scores), visual analogue scale and time of first exacerbation of the symptoms when loratadine was stopped.

Results: A total of 425 subjects were included. Using intent-to-treat analysis, the RQLQ global score decreased significantly more in the LP-33 group than in the placebo group (P=0.0255, difference=-0.286 (95% confidence interval (CI): -0.536; -0.035)). No significant differences were noted for the change of the rhinitis total symptom score 5 global score between groups (P=0.1288, difference=-0.452 (95% CI: -1.036; 0.132)). Significant differences in ocular symptoms (RQLQ) were observed between groups (P=0.0029, difference=-0.4087 (95% CI: -0.6768; -0.1407)).

Conclusions: This study performed by GPs shows that LP-33 improves the quality of life of subjects with persistent AR who are currently being treated with an oral H1-antihistamine. Whereas nasal symptoms had not changed, ocular symptoms had consistently improved.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Dietary Supplements*
  • Double-Blind Method
  • Endpoint Determination
  • Female
  • Histamine Antagonists / pharmacology
  • Humans
  • Lactobacillus*
  • Loratadine / therapeutic use
  • Male
  • Middle Aged
  • Patient Compliance
  • Pollen / adverse effects
  • Pollen / immunology
  • Probiotics / administration & dosage*
  • Quality of Life
  • Rhinitis, Allergic, Seasonal / drug therapy
  • Rhinitis, Allergic, Seasonal / immunology
  • Rhinitis, Allergic, Seasonal / therapy*
  • Seasons
  • Treatment Outcome


  • Histamine Antagonists
  • Loratadine