Daily consumption of Lactobacillus gasseri KS-13, Bifidobacterium bifidum G9-1, and B. longum MM-2 for eight weeks was associated with significantly improved scores on the Mini Rhinoconjunctivitis Quality of Life Questionnaire (MRQLQ), compared to placebo.
“Because this study was placebo-controlled and well blinded and the probiotic was confirmed to be present in the stool of the probiotic group, the differences can likely be attributed to one or the combination of the three probiotic strains used in the intervention,” wrote scientists from the University of Florida and MCC Statistical Consulting LLC (Gainesville, FL) in the American Journal of Clinical Nutrition .
“To our knowledge, this is the first randomized, placebo-controlled trial addressing the clinical relevance of this particular combination of 3 probiotic strains on quality of life related to self-identified seasonal allergies.”
The study was supported by Wakunaga of America Co., Ltd. and a grant from the USDA National Institute of Food and Agriculture Hatch Project.
The researchers recruited 173 people with seasonal allergies and randomly assigned them to consume either the probiotic combination (total dose of 3 billion colony-forming units (cfus) per day) or placebo for eight weeks during allergy season.
Results showed that MRQLQ scores significantly improved in the probiotics group by 0.70 from the start of the study, but no such change was observed in the placebo group. This result suggested, “the decrease in the probiotic group was clinically relevant,” said the researchers.
Blood analyses showed immunoglobulin (Ig) E concentrations increased over the six week period in the probiotic group, but these failed to reach statistical significance from placebo. The number of regulatory T cells (Tregs) also increased in the probiotic group, but again these failed to reach statistical significance from placebo.
“IgE and Tregs were not different between intervention groups; however, the observed increases from baseline to week 6 indicate immune stimulation, likely confirming exposure of the participants to allergens,” wrote the researchers.
Elucidation of the mechanism(s) of action
“It is plausible that probiotics, as commensal organisms, may serve a greater role in preventing allergies earlier in life when the immune system is still developing,” theywrote. “Our study demonstrates a potential benefit for healthy adults with self-identified seasonal allergies when the probiotic is administered starting at the greatest level of allergy symptoms. Prophylactic administration of the probiotic might potentiate the beneficial effects observed in this study.
“Future research should focus on the molecular mechanism by which probiotics modulate immune function. If elucidated, this information may lead to a more complete understanding if the role of commensal microorganisms in developing and maintaining immune balance,” they concluded.
Commenting independently on the study's findings, Mary Ellen Sanders, PhD, Consultant with Dairy & Food Culture Technologies, told us: “Little evidence from controlled human studies exists that probiotics can impact allergy symptoms in adults, so it is noteworthy that this study found that the probiotics tested improved rhinoconjunctivitis-associated quality of life scores.”
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi:10.3945/ajcn.116.140012
“Probiotics (Lactobacillus gasseri KS-13, Bifidobacterium bifidum G9-1, and Bifidobacterium longum MM-2) improve rhinoconjunctivitis-specific quality of life in individuals with seasonal allergies: a double-blind, placebo-controlled, randomized trial”
Authors: J.C. Dennis-Wall et al.