The body’s response to allergens is a complex process that involves immune and inflammatory pathways. The allergic response often manifests as allergic rhinitis, atopic dermatitis, and food allergies. It is estimated that those affected by these allergic responses account for more than 20% of the general population.
The incidence of pathologies associated with the allergic response is on the rise. Some researchers have proposed a link between gastrointestinal dysbiosis and allergic diseases. This is due to the important role played by the gastrointestinal microbiome in the development of the immune system. The microbiota have also been shown to modulate certain aspects of the immune system and their inflammatory responses. A meta-analysis involving data from more than 340,000 individuals associated antibiotic use in children under the age of 2 with an increased risk of contracting certain allergic diseases later in life, including food allergies, allergic rhinitis, asthma, and atopic dermatitis.
Recent clinical and preclinical research suggests that certain probiotics may support a healthy allergic response. A review article by Cukrowska and colleagues explored the role of different species within the Bifidobacterium genus in the presence of allergies in studies focused on infancy. In the early stages of life, the dominance of Bifidobacterium is believed to facilitate the development of certain aspects of the immune system related to the allergic response. Study conclusions indicate that the species of Bifidobacterium breve, in particular, may support a healthy allergic response.
One animal study included in the review by Cukrowska and colleagues explored the effects of the administration of Bifidobacterium breve M-16V with certain prebiotic molecules on a murine population. The study reported a protective effect against an acute allergic skin response and other signs of allergy. Cytokine analysis was performed and an intestinal Th1/Th2 balance was reported to be the underlying cause for this protective response.
Allergic rhinitis, commonly known as hay fever, is a noninfectious inflammatory condition characterized by nasal congestion and other related symptoms after exposure to an allergen. A randomized controlled trial by Anania and colleagues explored the efficacy of certai strains of probiotics in the presence of allergic rhinitis symptoms in the pediatric population. The study involved 250 school-aged children with a history of allergic rhinitis who were randomized to a treatment or a placebo arm. The treatment group received a mixture of Bifidobacterium animalis subsp. Lactis BB12 and Enterococcus faecium L3 daily for 3 months.
Anania and colleagues reported that the probiotic mixture statistically and significantly decreased the signs and symptoms of allergic rhinitis. The study also observed a significant decrease in certain traditional medical interventions typically associated with allergic rhinitis, including the use of antihistamines and local corticosteroids in the treatment group as compared to a placebo.
Clinical studies have also explored probiotic use in the presence of other allergic diseases. Aggregate data from several clinical trials involving probiotic use in infants showed a decreased risk of developing eczema when compared to a placebo.
A review article explored the role of Lactobacillus in support of a healthy allergic response. One study involved Lactobacillus acidophilus L-92 and found significant alleviation of nasal symptoms. Another study reported 33% fewer episodes of rhinitis in the presence of supplementation with Lactobacillus. Other species of Lactobacillus were shown to modulate the presence of Th2 cytokines interleukin (IL)-4 and IL-5. L. paracasei was shown in laboratory studies to induce IL-12 and inhibit IL-4. In addition, IL-12 is associated with Th1 activity and IL-4 with Th2, and therefore, Lactobacillus may help balance Th1/Th2 cytokine levels.
Researchers continue to elucidate the association between probiotic use and the allergic response. Evidence suggests that certain probiotics may support a healthy immune response, and they may provide protective support in the presence of an allergic response. Since the current clinical studies on this topic are relatively limited in sample size and other aspects of study design, further research is needed before conclusions regarding treatment and prevention can be drawn.
By Colleen Ambrose, ND, MAT