Along with the beginning of the spring and the increased concentration of pollen in the air, allergy season begins. Therefore, a large number of patients suffering from pollinosis join the patients struggling with this problem all year round. Approximately 1 billion people worldwide currently suffer from allergies, and these numbers are estimated to increase to 4 billion in the next 30-40 years . Especially people living in developed countries are at risk of developing allergies.
Why is this happening and where does the allergy come from?
The currently rising incidence of allergic disease has tentatively been explained by the ‘hygiene hypothesis’, which links a general decrease in microbial exposure of children in developed countries to reduced immune system stimulation 
The microbiota plays a crucial role in the balanced development of the human immune system throughout our lives, and especially during the establishment of immune functions in early childhood . It is possible that specific types of organisms are required for the proper development of the human immune system, such as bifidobacteria, lactobacilli and saprophytic mycobacteria .
One of the ways to modulate the microbiome (apart from a healthy diet, activity, contact with animals) is also proper probiotic therapy. Number of publications suggesting that probiotic therapy may contribute to reduction of allergy related diseases is increasing.
Most of trials is focused on preventive impact of probiotic intake on development of Atopic Dermatitis (AD) and results are very promising. Child’s AD is the first symptom of so called Allergic March, which, if left untreated, gradually evolves through food allergies, asthma and inhalant allergies. Potential inhibition of this reaction cascade can therefore be very helpful in the treatment of these diseases. Especially it’s worth to consider probiotic therapy among high risk children, when one of the parents or siblings suffer from allergy. Scientists were able to receive best results, when probiotics were provided prenatally to mothers in the last trimester of pregnancy and later to new-borns since the first day of life till 6 months old. Due to this intervention, occurrence of AD was half lower in the probiotic supplemented group than in placebo group, respectively 15/64 .
Strains that in some way protect against triggering the allergic cascade and atopic changes were also selected, among others: Lactococcus lactis W58, Bifidobacterium lactis W52, Bifidobacterium bifidum W23 .
What to do when you already developed allergy, does oral probiotics help then?
Few publications describe positive impact of certain probiotic strains in therapy of food allergies. Most effective turned out to be combination of probiotic with prebiotic which is synbiotic instead of just bacteria itself. The best effects are obtained among paediatric patients whose immune system still develops so it can still be targeted .
What about inhalant allergy?
For now, there are studies on animal models indicating that colonization with individual strains may adequately protect or predispose to the development of asthma . However, there are currently no studies confirming the beneficial effect on reducing the risk of inhalant allergy among people. However, such an impact cannot be ruled out, which is why researchers point out the need to continue research to seek new therapeutic strategies .