Vitamin D deficiency may exacerbate the role of metal exposure in depression: A cross-sectional analysis of NHANES data from 2007 to 2018

People are paying more and more attention to the effects of environmental factors such as heavy metals on depression, and heavy metals may destroy the homeostasis of vitamin D in the body by affecting human metabolism, and the lack of vitamin D will increase the risk of depression. There are few studies on vitamin D deficiency in depression caused by heavy metals, and it is not deep enough. Therefore, this study used logistic regression, restricted cubic spline curve, weighted quantile and Quantile g-computation model to analyze the effects of heavy metal exposure alone and in combination on vitamin D and depression, as well as the potential role of vitamin D deficiency in the process of heavy metal-induced depression. The results showed that cadmium exposure alone or in combination increased the risk of depression (P < 0.05). When Cd increased by 1 unit, the risk of depressive symptoms increased by 1.178 units. Arsenic and its compounds and lead affected vitamin D levels in the body and contributed the second highest or highest weight in the mixture (P < 0.05). It is worth noting that after grouping according to vitamin D deficiency, compared with the normal group, the mixed exposure of heavy metals in the vitamin D deficiency group had more types of metals related to depression and contributed more weight (P < 0.05). This study found that single metal or multi-metal mixed exposure is associated with depression. Vitamin D deficiency may increase the risk of depression. Vitamin D may be a potential factor in the treatment of depression caused by metal, and the specific mechanism of action needs further study.