VITAMIN K AND BONE TURNOVER IN POSTMENOPAUSAL WOMEN

越来越多的数据表明，维生素K(K)不足可能通过引起骨转换增加而导致骨质疏松症的发生。然而，目前可用的数据不允许就钾在骨代谢中的作用得出明确的结论。许多关于钾与骨骼健康有关的证据利用了血清低位羧化骨钙素(UcoC)的测量作为钾状态的敏感指标。当用ucoc升高来定义钾缺乏时，钾缺乏是非常常见的。然而，这种不足是否与骨骼相关，或者如果ucoC浓度升高只是普遍的营养不足的替代，目前尚不清楚。为了阐明钾缺乏在骨骼健康中的作用，我们提出了一项14个月的前瞻性、随机、双盲、安慰剂对照试验，对226名绝经后妇女补充K1。我们假设补充K1可以降低骨骼的周转率。为了验证这一假设，我们将使用K1剂量(1000微克/天)来最大限度地降低血清ucoC。我们的特定目标是通过检测血清骨钙素、骨特异性碱性磷酸酶、L型胶原N-端肽以及尿吡啶和脱氧吡啶来评估骨骼转换。如果钾缺乏导致高骨转换，这是低骨量和骨质疏松性骨折的已知危险因素，推荐的钾摄入量应该增加，补充K1成为标准预防性医疗保健的一部分。

Accumulating data suggest that vitamin K (K) insufficiency may contribute to osteoporosis development by causing by causing increased bone turnover. However, currently available data do not permit definitive conclusions to be drawn regarding a role of K in bone metabolism. Much of the evidence implicating K in bone health utilizes measurement of serum undercarboxylated osteocalcin (ucOC) as a sensitive indicator of K status. When ucOC elevation is used to define K inadequacy, insufficiency is extremely common. However, whether this "insufficiency has skeletal relevance, or if elevated ucOC concentration is simply a surrogate for generalized inadequate nutrition, is unknown. To clarify the role of K insufficiency in skeletal health, we propose a 14 month, prospective, randomized, double-blind, placebo controlled trial of K1 supplementation in 226 postmenopausal women. We hypothesize that K1 supplementation reduces skeletal turnover. To test this hypothesis we will use a K1 dose (1000 mcg/day) that produces maximal reduction in serum ucOC. Our specific objective is to assess skeletal turnover by measuring serum osteocalcin, bone specific alkaline phosphatase, and N-telopeptides of type l collagen, as well as urinary pyridinoline and deoxypyridinoline. If K insufficiency causes high bone turnover, a known risk factor for low bone mass and osteoporotic fracture, the recommended K intake should be increased and K1 supplementation become part of standard preventative medical care.