Ultra-high-performance liquid chromatography-tandem mass spectrometry analysis of serum metabolomic characteristics in people with different vitamin D levels

Vitamin D is a fat-soluble vitamin with multiple functions. However, the metabolism of people with different vitamin D concentrations is still unclear. Herein, we collected clinical data and analysed the serum metabolome of people with 25-hydroxyvitamin D (25[OH]D) ≥40 ng/mL (A), 30 ng/mL ≤25(OH)D <40 ng/mL (B) and 25(OH)D <30 ng/mL (C) by the ultra-high-performance liquid chromatography-tandem mass spectrometry method. We found that haemoglobin A1c, fasting blood glucose, fasting insulin, homeostasis model assessment of insulin resistance and thioredoxin interaction protein were enhanced, while HOMA-β was reduced with the decrease of 25(OH)D concentration. In addition, people in the C group were diagnosed with prediabetes or diabetes. Metabolomics analysis showed that seven, thirty-four and nine differential metabolites were identified in the groups B vs A, C vs A and C vs B, respectively. Metabolites associated with cholesterol metabolism and bile acid biosynthesis, such as 7-ketolithocholic acid, 12-ketolithocholic acid, apocholic acid, N-arachidene glycine and d-mannose 6-phosphate, were significantly upregulated in the C group compared with the A or B groups. In conclusion, the disorder of vitamin D metabolism may be related to cholesterol metabolism and bile acid biosynthesis. This study provided a basis for exploring the possible mechanism leading to abnormal vitamin D metabolism.