Emerging Inverse Association Between Low Exposure to Vanadium and Kidney Function Impairment: a Cross-Sectional Analysis of Japanese Residents.

Renal toxicity associated with high-level exposure to vanadium has been reported in humans. However, the association between low-level vanadium exposure and human kidney function remains unclear. A cross-sectional study was conducted among 2680 Japanese residents with low vanadium exposure. The urinary vanadium content was measured using inductively coupled plasma mass spectrometry. A multivariate logistic regression analysis was performed to examine the association between vanadium levels and abnormal estimated glomerular filtration rate (eGFR), proteinuria, and hematuria. Nagelkerke's pseudo-R2 (%) was calculated to identify the factors contributing to urinary vanadium. Stratified and mediation analyses were conducted to evaluate the mediating effects of metabolic factors on the association between vanadium and kidney function. The median urinary vanadium concentration among Japanese residents was 0.23 µg/L, which is approximately half of the Agency for Toxic Substances and Disease Registry general population reference value (0.5 µg/L) and significantly lower than those in other countries and regions. Multivariate logistic regression analysis demonstrated a significant negative association between urinary vanadium concentrations and the prevalence of abnormal eGFR and proteinuria, suggesting the potential relevance of vanadium in maintaining kidney function. The primary contributing factor to urinary vanadium levels was daily dietary intake, particularly fruit consumption. Mediation analysis indicated that lipid profiles accounted for 6.9% of the observed vanadium-eGFR association. This is the first study to demonstrate an inverse association between urinary vanadium levels and renal dysfunction, as represented by decreased eGFR. Further longitudinal and mechanistic studies are required to confirm the causal relationships.