Probiotics for the Treatment of Atopic Dermatitis in Adults: A Systematic Review and Meta-Analysis

Atopic dermatitis (AD) is a chronic inflammatory skin condition that affects individuals of all ages. While probiotics have been widely studied as a treatment option in children with AD, evidence regarding their efficacy in adults remains limited. To address this gap, we conducted a meta-analysis to evaluate the impact of probiotic supplementation on AD in adult populations. Seven randomized controlled trials (RCTs) were included in the analysis. Compared to placebo, probiotic treatment significantly reduced SCORAD (Scoring Atopic Dermatitis) values (weighted mean difference [WMD], -4.52; 95% confidence interval [CI], -6.89 to -2.15; P < 0.001; I² = 61.6%). Subgroup analyses indicated that both single-strain and mixed-strain probiotics demonstrated similar trends in SCORAD improvement, although mixed strains did not reach statistical significance. While overall cytokine levels showed no significant change after treatment, notable reductions in interleukin-4 (IL-4) and thymus- and activation-regulated chemokine (TARC) levels were observed (interleukin [IL]-4: WMD, -2.35; 95% CI, -3.23 to -1.47; TARC: WMD, -1.10; 95% CI, -1.49 to -0.71; both P < 0.001). These findings suggest that probiotics may offer clinical benefits for adults with AD, potentially by modulating inflammatory responses through the downregulation of IL-4 and TARC.