Can Probiotics Help Hay Fever? The Link Between Gut Bacteria And Allergies

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by Monica Thunder

on May 13, 2015

Stuffy noses, itchy throats, dry skin, puffy eyes, coughs and sneezes. Spring is here, and with it all of our least favorite allergy symptoms. But there’s hope: according to a recent study published in International Forum for Allergy and Rhinology, probiotics, or “good bacteria,” may mitigate the nastier side effects of seasonal allergies.

The study, conducted by researchers at Vanderbilt University School of Medicine in Nashville, TN, reviewed and analyzed results from 23 trial studies testing the efficacy of probiotics in allergy treatment. In total, they reviewed data from 1,919 patients. Through meta-analysis, the researchers found probiotics may improve quality of life for those suffering from allergic rhinitis.

According to the American College of Allergy, Asthma and Immunology’s (ACAAI) website, allergic rhinitis affects as many as 50 million people in the United States.

Depending on the season, common causes for allergic rhinitis — known as allergens — include pollen, dust, mold, insect stings and animal dander. According to the American Academy for Allergy Asthma and Immunology’s (AAAI) website, when an individual has an allergy, his or her immune system mistakes an otherwise harmless allergen for an invader. In response, the immune system tells cells to produce chemicals like histamine, which are responsible for all the discomforts of an allergic reaction.

Photo: Denise Torres | Shutterstock

Photo: Denise Torres | Shutterstock

Probiotics may mitigate allergies because of the connection between the gut microbiome — the millions of bacteria living in every human’s gut — and the immune system. According to Harvard Medical School’s website, certain kinds of gut bacteria are known to correct deficiencies in the immune system and bolster levels of white blood cells.

By changing the constitution of the gut microbiome, probiotics may prevent the immune system from flaring up in response to harmless allergens, said Dr. Justin Turner, the lead author of the study, in a LiveScience article.

In the studies used for the analysis, subjects took either a probiotic supplement or ate probiotic-rich foods like yogurt, kefir and sauerkraut. These foods often advertise their probiotic content on packaging — common listings include strains of Lactobacillus and Bifidobacterium, according to Harvard Medical School. The quality and quantity of probiotic content in any given food, however, is often inconsistent.

The trial studies analyzed by the Vanderbilt researchers each used “different strains of live bacteria, different dosages and different probiotic supplement formulations over different periods of time,” according to the LiveScience article. 17 of the 23 studies documented improvement in patients’ allergy symptoms. Six of the 23 studies found probiotics offered no benefit.

While a correlation between probiotics and improved allergy symptoms was evident, these inconsistencies prevent the researchers from making firm conclusions about the link between probiotics and allergy prevention.

“Probiotics may be beneficial in improving symptoms and quality of life in patients with allergic rhinitis; however, current evidence remains limited due to study heterogeneity and variable outcome measures. Additional high-quality studies are needed to establish appropriate recommendations,” the authors conclude.