Allergic rhinitis results from an inflammatory immune response triggered by inhaled pollen, dust mites, or animal dander. Pollen is a major cause of allergic rhinitis, and pollen allergy is more commonly known as seasonal allergies or hay fever. Symptoms of seasonal allergies occur shortly after inhaling pollen that the sufferer is allergic to and can include an itchy nose, mouth, eyes, throat, skin, problems with being able to smell, a runny nose, sneezing, and watery eyes. Allergies, including seasonal allergies, have steadily increased over the past fifty years to become a common problem. Rhinitis now affects more than 30% of the US adult population, according to patient-reported data, and over 14% of people are diagnosed with allergic rhinitis by a doctor.
In addition to the typical symptoms of hay fever, patients can experience reduced quality of life due to a lack of sleep, reduced productivity at work or school, emotional distress, and embarrassment due to the symptoms. Current medications used to treat the symptoms of allergies can have undesirable side effects, including dry mouth, drowsiness, and sleeplessness, which can in turn affect patients’ quality of life. This has encouraged the search for alternative treatment strategies, including probiotic bacteria as a new therapy for improving hay fever symptoms.
Probiotics are living microorganisms which may provide health benefits when consumed in sufficient amounts. The most commonly used probiotics include bacteria like Bifidobacteria and Lactobacilli. Probiotic bacteria have the potential to alter immune responses through a variety of mechanisms that could reduce allergic reactions to airborne allergens without the side effects of some current drugs. These potential mechanisms, depicted in Figure 1, include increasing regulatory T cells that damp down immune responses, and suppressing the production of IgE antibodies.
Reference: Hong et al. Immune Netw. 2017 Feb.
A recent meta-analysis of clinical trials reported that the majority of studies showed some improvement in seasonal allergies in response to probiotic treatment. However, contemporary evidence is still limited due to the wide variety of different probiotic bacteria used, the way probiotics are delivered (for example, in yogurt, capsules, or milk), the duration of the treatment, characteristics of the patients, and different primary and secondary study outcomes measured by researchers.
A probiotic containing three different strains of bacteria, given to older adults, was recently shown to be beneficial in affecting the immune system. More specifically, the researchers observed an increase in the anti-inflammatory cytokine interleukin-10. This effect suggests that this combination of probiotics could benefit people suffering from seasonal allergies.
In this study, the researchers set out to test whether this probiotic, containing Lactobacillus gasseri, Bifidobacterium bifidum, and Bifidobacterium longum, could improve quality of life for people suffering from seasonal allergies compared to a placebo. They also tested some potential mechanisms through which these probiotics could be altering immune responses that could explain any benefits seen in the participants’ seasonal allergies.
Allergic rhinitis is a common health issue that can negatively affect sufferers’ quality of life. This study was designed to determine whether quality of life improved for people with seasonal allergies in response to a daily dose of three probiotic bacteria, compared to the effects of placebo administration.