Effects of probiotics supplementation on skin photoaging and skin barrier function: A systematic review and meta-analysis

BackgroundUltraviolet (UV) irradiation is one of the major causes of skin aging. To date, there remains limited evidence on using oral probiotics for skin anti-photoaging. ObjectivesThis systematic review and meta-analysis aims to assess the effects of probiotics on skin photoaging. MethodsWe searched the PubMed and Embase databases for studies published until August 31, 2021, and included randomized controlled trials, murine randomized controlled experiments, and in vitro studies. Skin barrier function was compared between UV irradiated probiotics and controls. ResultsAfter given oral probiotics supplements, a significant reduction was shown in all types of measured MMPs in both murine and in vitro studies. Oral probiotics supplementation significantly reversed UV-induced increase of epidermal thickness (standardized mean differences [SMD] = -1.76; 95% confidence interval [CI] = -3.04 to -0.49; p = .007; I-2 = 81%), UV-induced increase trans-epidermal water loss (SMD = -1.72; 95% CI = -2.76 to -0.67; p = .001; I-2 = 57%), and UV-induced skin dehydration (SMD = 1.85; 95% CI = 1.16 to 2.55; p < .00001; I-2 = 4%). ConclusionsProbiotics are effective against skin photoaging in terms of MMP pathways and reversing skin barrier function from murine randomized data. Further randomized controlled trials on humans are required to warrant these results.