No effect of oral treatment with an intestinal bacterial strain, Lactobacillus rhamnosus (ATCC 53103), on birch-pollen allergy: a placebo-controlled double-blind study.

Oral probiotic bacteriotherapy with Lactobacillus rhamnosus has given promising results in small children with food allergy. We studied the effects of similar therapy in teenagers and young adults, who were allergic to birch pollen and apple food and had intermittent symptoms of atopic allergy and/or mild asthma. We conducted a double-blind, placebo-controlled study, in which respiratory and eye symptoms and use of medications in two groups were compared. Open oral challenge tests with a slice of apple were performed trice: before, during and after the birch-pollen season. There were 18 patients in each group. They used Lactobacillus rhamnosus for 5.5 months; 2.5 months before the pollen season, 1 month during the season (May), and 2 months after. The results were negative. The treatment did not alleviate the symptoms of the patients or reduce their use of medication during the birch-pollen season or the subsequent 2 months. The treatment did not significantly affect the symptoms caused by apple in the oral challenge tests. We found no indication of a beneficial treatment effect in our patients. As the number of patients was relatively small, conclusions should be drawn with caution.