Urinary arsenic and depressive symptoms among adults: A moderated mediation analysis of folate and dietary inflammation index.

BACKGROUND

Few studies have explored the effects of arsenic exposure on depressive symptoms and the underlying mechanisms of its influence on this relationship. This study aimed to assess the impact of urinary arsenic on depressive symptoms and the mediating and moderating roles of folate and dietary inflammation index (DII).

METHODS

Cross-sectional data from 9775 participants (≥20 years) in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2020 were used for analysis. Total urinary arsenic and its compounds (urinary arsenobetaine and dimethylarsenic acid), folate, and DII were objectively measured, and depressive symptoms were assessed using the PHQ-9 scale. A logistic regression model weighted by the dietary two-day sample was used to analyze the effects, and a moderated mediation analysis was performed using the PROCESS macro.

RESULTS

Elevated urinary arsenic concentrations significantly increased the risk of depressive symptoms among adults in the United States. That is, the odds ratio (OR) of depressive symptoms increased as urinary arsenic concentrations increased (from the first quartile to the fourth quartile), and all of these results are statistically significant (P < 0.05). High urinary arsenic levels reduced folate levels and ultimately increased the risk of depressive symptoms, and DII moderated this association. The effect of urinary arsenic on depressive symptoms was not different among subgroups.

CONCLUSION

High levels of anti-inflammatory diet and enhanced folate intake helped reduce the effects of urinary arsenic on depressive symptoms.