Efficacy of a probiotic supplement in patients with atopic dermatitis: a randomized, double-blind, placebo-controlled clinical trial.

Background Atopic dermatitis (AD) is a multifactorial long-standing inflammatory skin disease with a high incidence worldwide in both adults and children. According to the recognized correlation between skin and intestine-the so-called "gut-skin axis"-gut unbalances can affect skin by inducing systemic inflammation and triggering dermatological diseases such as AD. Objectives To evaluate the efficacy of a food supplement containing selected strains of probiotics in ameliorating AD symptoms and skin conditions in adult volunteers. Materials & methods Eighty adult subjects showing mild-to-severe AD, skin dryness, desquamation, erythema and itching were enrolled in a randomized controlled trial to receive, for 56 days, a placebo or a mixture of lactobacilli (L. plantarum PBS067, L. reuteri PBS072 and L. rhamnosus LRH020). The latter was chosen according to the patients' production of post-biotic metabolites and B-group vitamins, anti-inflammatory and anti-oxidant capacity and anti-microbial activity. Clinical and instrumental dermatological evaluation was performed at T0d, T28d and T56d, and then at T84d (after a one-month wash-out). Inflammatory cytokine levels from skin tape stripping, sampled close to AD lesions at T0d and T56d, were also measured. Results Subjects receiving the probiotic mixture showed an improvement in skin smoothness, skin moisturization, self-perception, and a decrease in SCORAD index as well as in the levels of inflammatory markers associated with AD at T28d, with a positive trend up to T56d which was maintained at T84d. Conclusions Administration of selected probiotic strains resulted in a fast and sustained improvement in AD-related symptoms and skin conditions.