Effects of oral administration of Lactobacillus acidophilus L-92 on the symptoms and serum cytokines of atopic dermatitis in Japanese adults: a double-blind, randomized, clinical trial

Objectives: Several studies on lactobacilli have demonstrated they are effective against atopic dermatitis (AD) in children, but there are very few reports of their effects in adults. We investigated the changes in AD symptoms in adults after the ingestion of the Lactobacillus acidophilus strain L-92 (L-92), which has been shown to have a curative effect on AD in children.

Methods: A double-blind, parallel-group, placebo-controlled comparison was performed on 49 AD patients aged ≥16 years using heat-killed L-92. Skin lesions were assessed using the SCORing AD (SCORAD) index before the start of L-92 ingestion and 4 and 8 weeks after ingestion. Serum cytokine and blood marker levels were measured 8 weeks after the start of L-92 ingestion.

Results: The group that ingested L-92 had lower SCORAD scores than the controls (p = 0.002). The L-92 group also had decreased ratios of change for eosinophil count (p = 0.03) and increased ratios of change for serum TGF-β (p = 0.03). Ratios of change for serum TGF-β rose significantly (p = 0.04) in patients showing mitigated symptoms with L-92 administration.

Conclusions: Administration of heat-killed L-92 was effective for AD symptoms in adults. L-92 may contribute to the suppression of Th2-dominant inflammation. Our preliminary trial is the first to report the effects of L-92 on adult AD.