Open Access Research

Changes in circulating 25-hydroxyvitamin D according to vitamin D binding protein genotypes after vitamin D3 or D2 supplementation

Hataikarn Nimitphong*, Sunee Saetung, Suwannee Chanprasertyotin, La-or Chailurkit and Boonsong Ongphiphadhanakul

Author Affiliations

Division of Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Rama 6 Rd, Rajthevi, Bangkok 10400, Thailand

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Nutrition Journal 2013, 12:39  doi:10.1186/1475-2891-12-39

Published: 4 April 2013

Abstract

Background

It is not known whether genetic variation in the vitamin D binding protein (DBP) influences 25-hydroxyvitamin D levels [25(OH)D] after vitamin D supplementation. We aimed to investigate the changes of total 25(OH)D, 25(OH)D3 and 25(OH)D2 in a Thai cohort, according to type of vitamin D supplement (vitamin D3 or D2) and DBP genotype, after receiving vitamin D3 or D2 for 3 months.

Methods

Thirty-nine healthy subjects completed the study. All subjects received 400 IU of either vitamin D3 or D2, plus a calcium supplement, every day for 3 months. Total serum 25(OH)D, 25(OH)D3 and 25(OH)D2 were measured by LC-MS/MS. Individual genotyping of rs4588 in the DBP gene was performed using real-time PCR.

Results

Vitamin D3 supplementation of 400 IU/d increased 25(OH)D3 significantly (+16.2 ± 4.2 nmol/L, p <0.001). Vitamin D2 (400 IU/d) caused increased 25(OH)D2 levels (+22.0 ± 2.11 nmol/L, p <0.001), together with a decrease of 25(OH)D3 (−14.2 ± 2.0 nmol/L, p <0.001). At 3 month, subjects in vitamin D3 group tended to have higher total 25(OH)D levels than those in vitamin D2 (67.8 ± 3.9 vs. 61.0 ± 3.0 nmol/L; p = 0.08). Subjects were then classified into two subgroups: homozygous for the DBP rs4588 C allele (CC), and the rest (CA or AA). With D3 supplementation, subjects with CA or AA alleles had significantly less increase in 25(OH)D3 and total 25(OH)D when compared with those with the CC allele. However, no difference was found when the supplement was vitamin D2.

Conclusion

Genetic variation in DBP (rs4588 SNP) influences responsiveness to vitamin D3 but not vitamin D2.

Keywords:
25-hydroxyvitamin D; Vitamin D3; Vitamin D2; Vitamin D binding protein(DBP)