Environmental Glyphosate Exposure Is Associated with Lower Serum 25-Hydroxyvitamin D Concentrations: A Cross-Sectional Analysis of NHANES 2013-2018.

Glyphosate is an herbicide used to control plant growth and ripen specific crops. Glyphosate exposure has been associated with cancer, metabolic and neurological diseases, and reproductive issues in humans. A common element linking these disorders could be vitamin D deficiency. However, the relationship between glyphosate exposure and vitamin D status in the general population remains unclear. This analysis focused on the association between urinary glyphosate levels and serum 25-hydroxy vitamin D [25(OH)D] concentrations in a large representative sample of U.S. adults. Data from 4284 participants in the National Health and Nutrition Examination Survey (NHANES) between 2013-2018 were analyzed. Serum 25(OH)D levels were modeled using multivariable weighted linear regression, with adjustment for age, sex, race/ethnicity, body mass index, season, education, income, physical activity, smoking, and kidney function. Urinary glyphosate concentration was inversely associated with serum 25(OH)D in both the design-based univariate weighted analysis (β = -3.537, p = 0.035) and adjusted survey-weighted models for major confounding factors (β = -4.208, p = 0.009), using Taylor linearization for variance estimation to account for the complex NHANES survey design. In stratified analysis, the relationship between total vitamin D intake and serum 25(OH)D was found to be significantly modified by glyphosate exposure, with stronger dietary dependence observed in the high-exposure tertile (β = 12.88, p < 0.0066) than in the low-exposure tertile (β = 7.41, p < 0.0165). Higher urinary glyphosate concentration was associated with lower serum 25(OH)D levels in U.S. adults, suggesting it may represent an unrecognized risk factor for vitamin D deficiency. Longitudinal and experimental studies are needed to clarify causality, the underlying mechanisms, and public health implications.