title: Plasma levels of 25-hydroxyvitamin D3 and in vivo markers of cytochrome P450 3A activity in Swedes and Koreans: effects of a genetic polymorphism and oral contraceptives.
abstract: In vitro studies have shown that vitamin D may induce several cytochrome P450 (CYP) enzymes in general and CYP3A4 in particular. The primary aim of this study was to investigate the relationship between plasma levels of 25-hydroxyvitamin D3 and suggested in vivo markers of CYP3A activity in healthy volunteers from Sweden and Korea. Plasma concentrations of 25-hydroxyvitamin D3 were analysed in samples from three previously performed studies, and the correlation between these levels and suggested in vivo markers of CYP3A activity was investigated by means of nonparametric correlation. In addition, we studied the modulating effects of three vitamin D receptor promoter polymorphisms on the association between 25-hydroxyvitamin D3 and CYP3A enzyme activity in Swedish subjects. The plasma levels of 25-hydroxyvitamin D3 were not significantly associated with CYP3A phenotypes in any of the three studies, but after accounting for the vitamin D receptor polymorphism rs4516035, there was a significant positive association between 25-hydroxyvitamin D3 and CYP3A activity (p = 0.004). Swedes (n = 65) had significantly higher 25-hydroxyvitamin D3 levels than Koreans (n = 67), 75 nM compared with 31 nM (p < 0.001). Swedish women taking oral contraceptives (OC) (n = 19) had somewhat higher plasma levels of 25-hydroxyvitamin D3 compared with Swedish women not taking oral contraceptives (n = 21), 89 and 72 nM, respectively (p = 0.02). In conclusion, our results suggest that the overall influence on the CYP3A activity by 25-hydroxyvitamin D3 is of marginal importance.
authors.affiliation: Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden.
authors.forename: Hanna
authors.initials: H
authors.lastname: Nylén
authors.forename: Linda
authors.initials: L
authors.lastname: Björkhem-Bergman
authors.forename: Lena
authors.initials: L
authors.lastname: Ekström
authors.forename: Hyung-Keun
authors.initials: HK
authors.lastname: Roh
authors.forename: Leif
authors.initials: L
authors.lastname: Bertilsson
authors.forename: Erik
authors.initials: E
authors.lastname: Eliasson
authors.forename: Jonatan D
authors.initials: JD
authors.lastname: Lindh
authors.forename: Ulf
authors.initials: U
authors.lastname: Diczfalusy
mesh_terms: D044466:Asian People / Q000235:genetics*; D015415:Biomarkers / Q000097:blood; D002784:Cholesterol / Q000097:blood; D002853:Chromatography, Liquid; D003276:Contraceptives, Oral / Q000008:administration & dosage*; D051544:Cytochrome P-450 CYP3A / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005838:Genotype; D064368:Healthy Volunteers; D006801:Humans; D006854:Hydrocortisone / Q000031:analogs & derivatives / Q000652:urine; D006888:Hydroxycholesterols / Q000097:blood; D016014:Linear Models; D008297:Male; D015999:Multivariate Analysis; D010641:Phenotype; D011110:Polymorphism, Genetic; D018167:Receptors, Calcitriol / Q000235:genetics / Q000378:metabolism; D056910:Republic of Korea; D013548:Sweden; D053719:Tandem Mass Spectrometry; D014807:Vitamin D / Q000097:blood*; D044465:White People / Q000235:genetics*
chemical_list: D015415:Biomarkers; D003276:Contraceptives, Oral; D006888:Hydroxycholesterols; D018167:Receptors, Calcitriol; D014807:Vitamin D; C099828:cholest-5-ene-3,4-diol; C001380:6 beta-hydroxycortisol; D002784:Cholesterol; D051544:Cytochrome P-450 CYP3A; D006854:Hydrocortisone