Dietary Intake Modifies the Association between Air Pollution and Chronic Diseases: A Systematic Review and Meta-analysis.

Interaction effects between dietary factors and air pollutants remain inconsistent. This systematic review and meta-analysis examined whether dietary intake modifies the air pollution-chronic disease risk association. This study searched PubMed, Embase, Web of Science, and the Cochrane from inception to May 2026. A total of 51 observational studies (cohort, case-control, and cross-sectional), comprising 9,956,549 participants, that examined the modifying effect of dietary intake on the association between air pollution exposure and chronic disease risk through stratified analyses were included. Stratum-specific pooled odds ratios (pORs) per 5 μg/m3 pollutant increase were estimated using random-effects models, whereas effect modification was assessed using deft analysis by pooling study-specific within-study interaction estimates. Particulate matter (PM) increased cardiovascular disease risk by 7%, attenuated by greater adherence to healthy dietary patterns (HDPs, P-int < 0.001, high compared with low intake pOR: 1.05 compared with 1.11), grain (P-int < 0.001, pOR: 1.04 compared with 1.06), and dairy (P-int < 0.001, pOR: 1.03 compared with 1.08), and amplified by sugar-sweetened beverage (SSB). PM and nitrogen oxides (NOX) increased chronic respiratory disease risk by 20% and 7%, respectively, attenuated by omega-3 (n-3) fatty acids (P-int = 0.002, pOR 1.05 compared with 1.09), and amplified by unhealthy dietary patterns (UDPs) and ω-6 fatty acids. PM and NOX increased metabolic disorder risk by 19% and 13%, respectively, attenuated by HDPs (PM: P-int < 0.001, pOR 1.04 compared with 1.24; NOX: P-int < 0.001, pOR 1.01 compared with 1.07), and amplified by UDPs, SSB, and sodium. PM increased neuropsychiatric and digestive disease risk by 9% and 17%, respectively, attenuated by vitamin B (dementia: P-int < 0.001, pOR: 0.95 compared with 1.18). These findings suggest that greater adherence to HDPs, grain, dairy, ω-3 fatty acids, and vitamin B may attenuate the association between PM and NOX exposure and chronic disease risk. This review was registered in PROSPERO as CRD420251148066.