Associations between diet quality and multiple chemical exposures

OBJECTIVE: Diet is recognized as both a determinant of health and a potential exposure source of environmental chemicals, but evidence linking comprehensive dietary indices to chemicals remains limited. We investigated the associations between diet quality, measured by the Healthy Eating Index 2020 (HEI-2020), and exposures to multiple environmental chemicals in a nationally representative U.S. METHODS: NHANES 2017-2020 data (n = 4944) were used for the primary analysis, and NHANES 2013-2020 data (n = 11,739) were used for multi-cycle validation. Survey-weighted regression models assessed associations between HEI-2020 scores and chemical concentrations. Generalized additive models explored nonlinearity, and component-level analyses identified dietary components contributing to selected associations. RESULTS: Higher HEI-2020 scores were positively associated with urinary nitrate (β = 0.008), urinary arsenic (β = 0.002), and blood mercury (β = 0.005). Negative associations were observed for blood cadmium (β = -0.001) and perfluorononanoic acid (β = -0.002). Arsenic and mercury showed nonlinear patterns, and multi-cycle analyses supported the general stability of most associations. Component-level analyses suggested that vegetables and greens were major contributors to the nitrate association, seafood and plant proteins were related to mercury and arsenic, and fruit components were inversely associated with cadmium. CONCLUSION: Healthier diet patterns may accompany beneficial nutrients but also elevate certain contaminant exposures. These results support integrated nutrition and environmental health strategies to maximize dietary benefits while minimizing toxicant exposure.