Tsugawa Naoko, Shiraki Masataka, Suhara Yoshitomo, Kamao Maya, Tanaka Kiyoshi, Okano Toshio
Department of Hygienic Sciences, Kobe Pharmaceutical University, Kobe, Japan.
Am J Clin Nutr. 2006 Feb;83(2):380-6. doi: 10.1093/ajcn/83.2.380.
Vitamin K deficiency is associated with low bone mineral density and increased risk of bone fracture. Phylloquinone (K1) and menaquinone 4 (MK-4) and 7 (MK-7) are generally observed in human plasma; however, data are limited on their circulating concentrations and their associations with bone metabolism or with gamma-carboxylation of the osteocalcin molecule.
The objectives were to measure the circulating concentrations of K1, MK-4, and MK-7 in women and to ascertain whether each form of vitamin K is significantly associated with bone metabolism.
Plasma concentrations of K1, MK-4, MK-7, undercarboxylated osteocalcin (ucOC; measured by using the new electrochemiluminescence immunoassay), intact osteocalcin (iOC), calcium, and phosphorus; bone-derived alkaline phosphatase activity; and concentrations of urinary creatinine, N-terminal telopeptide, and deoxypyridinoline were measured in healthy women (n = 396).
On average, MK-7 and MK-4 were the highest and lowest, respectively, of the 3 vitamers in all age groups. K1 and MK-7 correlated inversely with ucOC, but associations between nutritional basal concentration of MK-4 and ucOC were not observed. Multiple regression analysis indicated that not only K1 and MK-7 concentrations but also age were independently correlated with ucOC concentration and the ratio of ucOC to iOC. The plasma K1 or MK-7 concentration required to minimize the ucOC concentration was highest in the group aged > or =70 y, and it decreased progressively for each of the younger age groups.
The definite role of ucOC remains unclear. However, if submaximal gamma-carboxylation is related to the prevention of fracture or bone mineral loss, circulating vitamin K concentrations in elderly people should be kept higher than those in young people.
维生素K缺乏与低骨矿物质密度及骨折风险增加相关。叶绿醌（K1）、甲萘醌4（MK - 4）和甲萘醌7（MK - 7）通常存在于人体血浆中；然而，关于它们的循环浓度及其与骨代谢或骨钙素分子γ-羧化作用的关联的数据有限。
测定女性体内K1、MK - 4和MK - 7的循环浓度，并确定每种维生素K形式是否与骨代谢显著相关。
测量了396名健康女性血浆中K1、MK - 4、MK - 7、未羧化骨钙素（ucOC；采用新型电化学发光免疫分析法测量）、完整骨钙素（iOC）、钙和磷的浓度；骨源性碱性磷酸酶活性；以及尿肌酐、N端肽和脱氧吡啶啉的浓度。
在所有年龄组中，平均而言，3种维生素形式中MK - 7含量最高，MK - 4含量最低。K1和MK - 7与ucOC呈负相关，但未观察到MK - 4的营养基础浓度与ucOC之间的关联。多元回归分析表明，不仅K1和MK - 7浓度，年龄也与ucOC浓度以及ucOC与iOC的比值独立相关。使ucOC浓度降至最低所需的血浆K1或MK - 7浓度在年龄≥70岁的组中最高，且在每个较年轻年龄组中逐渐降低。
ucOC的明确作用仍不清楚。然而，如果亚最大程度的γ-羧化与预防骨折或骨矿物质流失有关，则老年人的循环维生素K浓度应保持高于年轻人。
