Human exposure to heavy metals through the environment or food is inevitable. Vitamin D (VitD) has various effects on the body, such as bone regeneration and immune function. VitD activity is known to be inhibited by heavy metals, but it is known that VitD metabolism in the body also stimulates the absorption of heavy metals. To predict VitD activity, it is important to find the endogenous metabolites that affect VitD activity. Therefore, we aimed to identify the effect of endogenous metabolites altered by heavy metals levels on VitD activity.

Using ultra-high performance liquid chromatography and quadrupole time-of-flight/mass spectrometry, plasma samples of 52 were analyzed. Untargeted metabolic profiling with deficiency 25-hydroxyvitamin D [25(OH)D] and low heavy metals (lead, cadmium, mercury, and arsenic) (Group A) and insufficiency 25(OH)D and high heavy metals (Group B) was conducted.

Multivariate analysis showed a clear separation between Group A and Group B. Putative metabolites with variable importance in the projection value more than 1.0 and p-value less than 0.05 were searched: Phosphocholine and 17,18-dihydroxyeicosatetraenoic acid (17,18-DiHETE). These metabolites were increased in Group A compared to Group B (p<0.05). Phosphocholine is related to the biosynthesis of phospholipids, and 17,18-DiHETE is included in the eicosapentaenoic acid metabolism which is known to reduce inflammation. Further studies are required to confirm the effect of putative metabolites on VitD activity.