Date of Award

Spring 3-13-2013

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Nutrition

First Advisor

Meera Penumetcha

Second Advisor

Anita M. Nucci

Third Advisor

Barbara Hopkins

Abstract

Background: About 1 in every 6 Americans suffer from seasonal allergies, aka allergic rhinitis (AR), every year. Typical symptoms of AR include sneezing, stuffy nose and watery eyes. Currently, two types of medications, anti-histamines and corticosteroids, are widely used for relieving AR symptoms; however, in addition to the concern about drug resistance after their long-term use, they also cause side effects such as dry mouth and dizziness.

Introduction: AR results from an abnormally heightened immune response triggered by unharmful substances in the environment. Therefore, a therapy capable of regulating the overall immune function of the body should alleviate the discomfort caused by AR. The intestine is the largest immune organ of the body. And consumption of probiotics can induce positive changes in the composition of the microbiota that reside in the intestine within a short period of time. As a result, several trials have been conducted to investigate the therapeutic effects of probiotics on AR. However, because of the generally small sample size of these studies, it is difficult to reach a definite conclusion. Therefore, we performed a meta-analysis to assess if probiotics consumption leads to improvement of AR symptoms.

Method: Key words of “probiotics” and “seasonal allergy” were used to search PubMed, Cochrane and CINAHL to identify randomized controlled trials for the meta-analysis. Out of the 69 initially identified papers, 9 were eventually included in the analysis. Studies excluded were either duplicates, reported un-relevant outcomes, or provided insufficient data for further analysis. The meta-analysis was conducted through CMA 2.0, commercial comprehensive meta-analysis software. Standardized mean difference was calculated for subjective symptoms scores and serum biomarker levels for each study as the effect size, and the random effects model was applied to calculate the overall effect.

Results: In the Forest plot, the Hedges’ g value for overall symptom score was 0.451 with a p value of 0.02, indicating that probiotics consumption induced a moderate improvement in symptoms, and the improvement is statistically significant. On the other hand, the Hedges’ g value for blood biomarkers level was -0.15 with a p value of 0.127, meaning probiotics performed worse than placebo at decreasing the inflammation at cellular or molecular level, as measured by serum biomarkers, but this inferior effect was not statistically significant.

Conclusion: The use of probiotics is beneficial at relieving allergic symptoms for AR patients, but contradictory findings were discovered when it comes to the measurement of serum biomarkers levels. Future studies are needed to identify reliable biomarkers for AR, and studies with similar design but larger sample size would be helpful to further investigate the effectiveness of probiotics in the management of AR.

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