Objective  To explore the effects of serum vitamin C (VC) and vitamin D₃ (VD₃) on antioxidant capacity in women.

  Methods  We collected 124 serum samples with convenient sampling from healthy female physical examinees aged 25 to 45 years from January through February 2017 at Shanxi Minsheng Medical Center in Taiyuan city of Shanxi province. The content of serum VC was determined with high performance liquid chromatography with ultraviolet detection and thereafter the participants were divided into a high VC group (serum VC≥2 μg/mL) and a low VC group (< 2 μg/mL). Enzyme linked immunosorbent assay was used to detect the contents of 25-hydroxyvitamin D₃ (25-(OH) D₃) and 1,25-dihydroxy D₃ (1,25-(OH)₂D₃). The activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were detected with colorimetric assay. The differences in all the indicators were compared between the high and low VC group. Then a 30-day vitamin D₃ (VD₃) supplement intervention at daily dose 20 μg was conducted among 65 voluntary participants of high VC group with the serum 25-(OH)D₃ < 30 ng/mL and the serum samples of the 65 participants were collected on April 6, 2017 for the evaluation of variations in 25-(OH)D₃, 1,25-(OH)₂D₃, SOD and GSH-Px after the intervention.

  Results  Compared to those in the participants of low VC group, higher serum 25-(OH)D₃ (22.65 ± 5.51 ng/mL), 1,25-(OH)₂D₃ (19.10 ± 5.60 pg/mL), SOD activity (79.25 ± 26.98 U/mL), and GSH-Px (32.73 ± 6.06 nmol/mL) were observed in the participants of high VC group and were of statistical significance (P < 0.05) except for serum 25-(OH)D₃. The results of serum detection in all the participants demonstrated that VC was positively correlated with 1,25-(OH)₂D₃ and SOD, GSH-Px.25-(OH)D₃ was positively correlated with 1,25-(OH)₂D₃, and 1,25-(OH)₂D₃ was positively correlated with SOD. Significantly increased serum 25-(OH)D₃ (40.66 ± 12.12 ng/mL), 1,25-(OH)₂D₃ (24.79 ± 4.93 pg/mL), SOD activity (86.05 ± 26.95 U/mL), and GSH-Px activity (42.11 ± 8.22 nmol/mL) were measured among the participants after the completion of VD₃ supplement intervention (P < 0.05 for all).

  Conclusion  Serum VC at a certain content range could promote the activation of serum VD₃ to 1,25-(OH)₂D₃ and serum VC and VD₃ could reduce oxidative stress and improve the antioxidant capacity among 25 to 45 years old women.