Dietary Polyunsaturated Fatty Acids Intake, Air Pollution, and the Risk of Lung Cancer: A Prospective Study in UK Biobank.

Background: Epidemiological evidence on the association between specific types of polyunsaturated fatty acids (PUFAs) intake and lung cancer risk is limited. However, whether dietary-specific PUFAs intake can modify the asso-ciation between air pollutants and incident lung cancer remains unknown. Methods: Cox proportional hazard models and restricted cubic spline regression were used to evaluate the associations of omega-3 PUFAs, omega-6 PUFAs and the ratio of omega-6 PUFAs to omega-3 PUFAs intake with lung cancer risk. Furthermore, we evaluated the associations between air pollutants and incident lung cancer, and whether dietary -specific PUFAs intake would modify the relationship using stratification analyses. Results: This study found significant associations between the risk of lung cancer and omega-3 PUFAs intake (hazard ratio [HR], 0.82; 95 a/o confidence interval [CI], 0.73-0.93; per 1 g/d), and omega-6 PUFAs intake (HR, 0.98; 95 a/o CI, 0.96-0.99; per 1 g/d). We did not observe an association between the omega-6 to omega-3 PUFAs intake ratio and incident lung cancer. With regard to air pollution, omega-3 PUFAs intake attenuated the positive relationship be-tween nitrogen oxides (NOx) pollution and lung cancer risk, and an increased incidence of lung cancer was found only in the low omega-3 PUFAs intake group (p < 0.05). Surprisingly, PUFAs intake (regardless of omega-3 PUFAs, omega-6 PUFAs, or in total) reinforced the pro-carcinogenic effects of PM2.5 on lung cancer, and a positive association between PM2.5 pollutants and incident lung cancer was observed only in the high PUFAs groups (p < 0.05). Conclusions: Higher dietary omega-3 and omega-6 PUFAs intake was associated with a decreased risk of lung cancer in the study population. As omega-3 PUFAs have different modification effects on NOX and PM2.5 air pollution related lung cancer incidence, precautions should be taken when using omega-3 PUFAs as health-promoting dietary supple-ments, especially in high PM2.5 burden regions.