According to one theory, the cause of such a widespread occurrence of atopic diseases, such as allergic rhinitis, asthma or eczema, are qualitative and quantitative changes in the intestinal microflora. Thus, in people suffering from these diseases, an increased content of clostridia and a reduced content of bifidobacteria in the stool have been found.

Probiotics are living microorganisms which, when given in adequate amounts, have a beneficial effect on health. The consumption of certain probiotics (lactobacilli and bifidobacteria) has been shown to stimulate an anti-inflammatory and anti-allergic response, probably due to their ability to compensate for disturbances in the composition of the microflora and to normalize the permeability of the intestinal wall. Another hypothesis is that probiotics improve the specific IgA response and reduce the production of cytokines associated with allergic inflammation.

The following clinical trials evaluate the prophylactic and therapeutic effect of probiotics in atopic diseases.

In a randomized, placebo-controlled study of 159 pregnant women with a history of atopy (eczema, rhinitis, asthma, the patient, her immediate family or her husband) took 2 capsules of Lactobacillus rhamnosus GG (1x1010 CFU / day) or a placebo in 2 to 4 weeks before birth. For the next 6 months, breastfeeding mothers or the children themselves continued to receive the same medication. When examining children 24 months of age, the incidence of atopic eczema was 23% in children receiving a probiotic versus 46% in the placebo group (relative risk (RR) 0.51; confidence interval (CI) 95% 0.32-0.84, p = 0.0008). A similar trend was observed in the group of breastfed children (15% vs 47%, respectively; RR 0.32; 95% CI 0.12-0.85), as well as in re-examination of children after 2 years (26% vs 46%, respectively; RR 0.57; 95% CI 0.33-0.97), while the frequency of positive skin scarification tests for food allergens did not differ between the groups (20% in the probiotic treatment group and 18% in the control group).

A placebo-controlled study evaluating the efficacy of Lactobacillus rhamnosus GG in children with atopic eczema and cow's milk allergy was followed by 31 children (ages 2.5 to 15 ,7 months). All children received a highly hydrolyzed whey nutritional formula with or without the addition of Lactobacillus rhamnosus GG (5x108 CFU / g) for 1 month. The severity of the disease was assessed on a SCORAD scale. During the evaluation after 1 month, a significant decrease in the total score was observed in children receiving the probiotic (from 26 to 15, p = 0.008), compared to the placebo group (from 21 to 19 points, p = 0 , 89). However, there were no other differences between the groups, and after 2 months, the scale indicators were almost equal (16 and 14, respectively). Similar results have been observed in several other studies.

The study involved 38 adolescents and young people allergic to birch pollen (respiratory manifestations and conjunctivitis) and received L. rhamnosus GG (2 capsules containing 5x109 CFU 2 times / day) or a placebo for 5.5 months (2.5 months before the start of the season, 1 month during the season - May and 2 months after its end). Symptoms were assessed on a 10-point scale separately for ocular, nasal and pulmonary manifestations. The study found no effect of probiotic therapy on the severity of symptoms of the disease during the season and for the next 2 months.

Another placebo-controlled study of a similar design noted an improvement in quality of life after 30 days in a group of children receiving Lactobacillus paracasei -33 (2x109 CFU / vial), who s is manifested by a decrease in the incidence of rhinitis symptoms (p = 0.037) and the degree of inconvenience they cause (p = 0.022).

Probiotics are considered safe drugs with good tolerance. However, in one study, adverse events from the gastrointestinal tract were noted with L. rhamnosus GG; while using L.paracasei -33, no serious adverse event has been detected. Several cases of severe infections have also been reported in patients with immunodeficiency during probiotic therapy.

Thus, in one of the studies, the pronounced prophylactic effect of taking probiotics in atopic diseases has been demonstrated, but their effectiveness as therapeutic agents remains controversial. Products and preparations containing probiotics are already on sale and, in a number of countries, they are classified as food and not as medicine. In addition, there are currently no recommendations on the optimal dose of microorganisms, as well as the most suitable diet for their use for the prevention and treatment of atopic diseases.