Vitamin K supplementation reduces serum concentrations of under-gamma-carboxylated osteocalcin in healthy young and elderly adults.
BACKGROUND
Subclinical vitamin K insufficiency, manifested by under-gamma-carboxylation of the bone matrix protein osteocalcin, may be common.


OBJECTIVE
Our objective was to delineate the prevalence of submaximal gamma-carboxylation as assessed by response to phylloquinone supplementation and to evaluate the effect of this intervention on skeletal turnover in healthy North American adults.


METHODS
Healthy subjects (n = 219), approximately equally distributed by sex and age (18-30 y and >/=65 y), received daily phylloquinone (1000 microg) or placebo for 2 wk. Serum undercarboxylated osteocalcin (ucOC) and total osteocalcin, N:-telopeptides of type I collagen (NTx), bone-specific alkaline phosphatase (BSAP), and phylloquinone concentrations were measured at baseline and after weeks 1 and 2.


RESULTS
At baseline, the mean serum phylloquinone concentration was lower in the young than in the old group; there was no effect of sex. Concomitantly, baseline %ucOC was highest in the young and lowest in the old men (P: < 0.0001) but did not differ significantly by age in women. After supplementation, serum phylloquinone concentration increased approximately 10-fold (P: < 0.0001) at week 1 (from 0.93 +/- 0.08 to 8.86 +/- 0.70 nmol/L, x+/- SEM); this was sustained through week 2. Among all supplemented groups, mean %ucOC decreased from 7.6% to 3. 4% without significant differences by age or sex; 102 of 112 subjects had a >1% decrease. Phylloquinone supplementation reduced serum osteocalcin but did not alter NTx or BSAP concentration.


CONCLUSIONS
Usual dietary practices in this population did not provide adequate vitamin K for maximal osteocalcin carboxylation. Phylloquinone supplementation reduced serum osteocalcin concentration but did not alter other markers of serum bone turnover.
Binkley
N C
NC
Institute on Aging, Department of Medicine, University of Wisconsin, Madison, WI, USA. nbinkley@facstaff.wisc.edu
Krueger
D C
DC
Engelke
J A
JA
Foley
A L
AL
Suttie
J W
JW
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D000704:Analysis of Variance; D000933:Antifibrinolytic Agents / Q000494:pharmacology*; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008297:Male; D015675:Osteocalcin / Q000097:blood* / Q000187:drug effects*; D016037:Single-Blind Method; D010837:Vitamin K 1 / Q000097:blood / Q000494:pharmacology*
D000933:Antifibrinolytic Agents; D015675:Osteocalcin; D010837:Vitamin K 1