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.