The efficacy and safety of heat‐killed <i>Lactobacillus paracasei</i> for treatment of perennial allergic rhinitis induced by house‐dust mite

Live Lactobacillus paracasi 33 (LP33) may effectively improve the quality of life for patients with perennial allergic rhinitis. It has been demonstrated that heat-killed lactic acid bacteria (LAB) suppress specific immunoglobulin E synthesis and stimulate interleukin-12 production in animals. The aim of this study was, therefore, to evaluate the efficacy of heat-killed LP33 in the treatment of allergic rhinitis induced by house-dust-mite in human subjects. A total of 90 patients were enrolled in a randomized, double blind, placebo-controlled trial and assigned to three treatment groups. Patients in groups A and B received two capsules per day of live or heat-killed LAB (5 x 10(9) colony-forming units/capsule), respectively, over a period of 30 days while those in Group C received placebo capsules. A modified questionnaire on pediatric rhinoconjunctivitis-related quality of life was administered to all subjects or their parents during each clinical visit. The overall quality of life score decreased for groups A and B, as compared with the placebo group, in terms of both frequency (9.47 +/- 2.89, 6.30 +/- 2.19, vs. -3.47 +/- 1.53, respectively; p < 0.0001) and level of bother (5.91 +/- 3.21, 6.04 +/- 2.44, vs. -2.80 +/- 1.64, respectively; p = 0.004) after the 30-day treatment. The efficacy of the heat-killed LP33 was not inferior to the live variant. No obvious side effects were reported for either active treatment group during the study period. Our results suggest that heat-killed LP33 can effectively improve the overall quality of life for patients with allergic rhinitis, and that it may be efficacious as an alternative treatment.