Protective effects of dietary fish‐oil supplementation on skin inflammatory and oxidative stress biomarkers induced by fine particulate air pollution: a pilot randomized, double‐blind, placebo‐controlled trial*

Exposure to fine particulate matter (with an aerodynamic diameter ≤ 2·5 μm, PM2·5 ) air pollution has been associated with skin-related diseases or disorders.To evaluate the potential skin-protective effects of fish-oil supplementation against PM2·5 exposure.This is an exploratory analysis based on a pilot randomized, double-blind, placebo-controlled trial among 65 healthy young adults between September 2017 and January 2018 in Shanghai, China. We randomly assigned participants to take either fish oil or placebo 2·5 g daily for four consecutive months. Four rounds of skin D-Squame® tape samples were collected in the last 2 months, and five secondary biomarkers of skin inflammation and oxidative stress were measured. Fixed-site PM2·5 concentrations on campus were measured in real time. We used linear mixed-effect models to analyse the associations between short-term PM2·5 exposure and biomarkers in each group.The 24-h average PM2·5 concentration was 34·68 ± 15·83 μg m-3 . There were generally weaker associations between PM2·5 and biomarkers in the fish-oil group than in the placebo group, but the associations and the between-group differences varied by biomarkers and lag periods. Compared with the placebo group, for a 10-μg m-3 increase in PM2·5 concentration, the increments of interleukin-1α and carbonyl protein in the fish-oil group were 41·55% smaller [95% confidence interval (CI) 4·61-78·48%] at lag 0-48 h and 22·01% smaller (95% CI 11·25-32·77%) at lag 0-24 h, respectively. No significant between-group differences were observed for other biomarkers.This study suggested that dietary fish-oil supplementation may improve biomarkers of skin inflammation and oxidative-stress response to short-term PM2·5 exposure.