title: Vitamin D-vitamin K interaction: effect of vitamin D supplementation on serum percentage undercarboxylated osteocalcin, a sensitive measure of vitamin K status, in Danish girls.
abstract: There is some evidence for a nutritional interaction between vitamin D and vitamin K status. We have recently reported that serum percentage undercarboxylated osteocalcin (%ucOC; a marker of vitamin K status) was inversely correlated with serum 25-hydroxyvitamin D (25(OH)D) concentration (reflective of vitamin D status) in healthy Danish girls (aged 11-12 years), in line with a similar relationship reported in elderly women. While the causal nature of the relationship between vitamin D status and serum %ucOC has been tested in studies of elderly women, it has not been investigated in children. The objective of the present study was to test the hypothesis that improving vitamin D status significantly lowers serum %ucOC. Serum samples from sixty-seven healthy Danish girls (aged 11-12 years), who participated in a 12-month double-blind, placebo-controlled, vitamin D3 intervention trial were used for the present study. These girls were a subset of subjects which began and finished the intervention during wintertime, thus avoiding the influence of seasonality on vitamin D status. A total of thirty-three and thirty-four of the girls had been randomised to treatment with 10 μg vitamin D3 per d and placebo, respectively, for 12 months. Total osteocalcin and the fraction of ucOC in serum (via enzyme-immunoassay) as well as serum 25(OH)D (via HPLC) were assessed at baseline and end-point. Vitamin D3 supplementation significantly increased serum 25(OH)D (21.6 %; P < 0.002) but had no effect on serum %ucOC (P>0.8). In conclusion, the findings of the present intervention study in young girls suggest that vitamin D supplementation does not affect serum %ucOC, a marker of vitamin K status.
authors.affiliation: School of Food and Nutritional Sciences, University College Cork, Cork, Republic of Ireland.
authors.forename: Eibhlís
authors.initials: E
authors.lastname: O'Connor
authors.forename: Christian
authors.initials: C
authors.lastname: Mølgaard
authors.forename: Kim F
authors.initials: KF
authors.lastname: Michaelsen
authors.forename: Jette
authors.initials: J
authors.lastname: Jakobsen
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Cashman
mesh_terms: D002648:Child; D002762:Cholecalciferol / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D019587:Dietary Supplements; D004311:Double-Blind Method; D004347:Drug Interactions; D005260:Female; D006801:Humans; D015675:Osteocalcin / Q000097:blood* / Q000378:metabolism; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014812:Vitamin K / Q000008:administration & dosage* / Q000493:pharmacokinetics*
chemical_list: D015675:Osteocalcin; D014812:Vitamin K; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D