Fish oil supplementation and risk of incident systemic lupus erythematosus: a large population-based prospective study.

Background: Although fish oil has been considered to have an anti-inflammatory effect and has been proven to play a beneficial role in the incidence of numerous diseases, the association between fish oil supplementation and the risk of systemic lupus erythematosus (SLE) is still unknown. This study aimed at evaluating the correlation between fish oil use and incident SLE in a large population-based prospective cohort.

Methods: 390,277 participants without SLE at baseline from the UK Biobank were enrolled. Fish oil use was ascertained through a touchscreen questionnaire at baseline. The incidence of SLE was identified by the International Classification of Diseases version 10 code in medical records or self-report. Cox proportional hazard models were employed to estimate the association between fish oil use and SLE risk.

Results: Fish oil users accounted for 31.47% of participants. During a median follow-up duration of 11.57 years, 141 participants without fish oil use (4.56/100 000 person-years) and 68 participants with fish oil use (4.78/100 000 person-years) developed SLE. In four models with adjustments for different amounts of confounders, there was no significant difference in the risk of SLE between fish oil users and fish oil non-users (all p-values > 0.05). In subgroup analyses, we found that fish oil supplementation was associated with a lower risk of SLE among females with ultraviolet radiation ≥ 3 h/day (hazard ratio: 0.63, 95% confidence interval: 0.40-0.98), which turned insignificant after further adjustment for female-related factors and sun protection measures.

Conclusions: No significant association between fish oil use and overall incident SLE was observed, except in females exposed to prolonged ultraviolet radiation. Subgroup analysis suggested that females exposed to prolonged ultraviolet radiation might benefit from fish oil supplementation in terms of preventing SLE, but it needs to be confirmed in further studies.