Kuwabara Akiko, Fujii Minori, Kawai Nobuko, Tozawa Kunihiko, Kido Shoko, Tanaka Kiyoshi
Department of Food and Nutrition, Kyoto Women's University, 35, Imakumano-kitahiyoshicho, Higashiyama 605-8501 Japan.
Asia Pac J Clin Nutr. 2011;20(1):50-5.
In Japan, γ-carboxylation of blood coagulation factors is the basis for determining adequate intake (AI) for vitamin K in Dietary Reference Intakes (DRIs) issued in 2010. Recently, vitamin K is also known to be essential for preventing fracture. In this study, relative susceptibility of liver and bone to vitamin K deficiency was studied. Thirty-seven elderly institutionalized subjects were evaluated for vitamin K status by measuring serum PIVKA (protein induced by vitamin K absence) -II and ucOC (undercarboxylated osteocalcin) levels, as sensitive markers for hepatic and skeletal vitamin K deficiency, respectively. Serum PIVKA-II and ucOC levels, with their cut-off values in the parentheses, were 20.2±8.9 mAUmL (28 mAU/mL) and 4.7±3.0 ng/mL (4.5 ng/mL), respectively. Median vitamin K intake was approximately 200 μg/day, which is more than 3 times higher than the current Japanese AI. Vitamin K intake was significantly correlated with serum PIVKA-II and ucOC/OC levels, but not with serum ucOC level. Although serum ucOC level is generally a good indicator for vitamin K status, multiple regression analysis revealed that elevated bone turnover marker significantly contributed to serum ucOC level. All subjects had vitamin K intake exceeding AI for vitamin K. Nevertheless, serum PIVKA-II and ucOC concentrations exceeded the cut-off value in 14% and 43% of subjects, respectively. The present findings suggest that vitamin K intake greater than the current AI is required for the skeletal health in the institutionalized elderly.
在日本，凝血因子的γ-羧化作用是确定2010年发布的膳食参考摄入量（DRIs）中维生素K适宜摄入量（AI）的依据。最近，维生素K还被认为对预防骨折至关重要。在本研究中，对肝脏和骨骼对维生素K缺乏的相对易感性进行了研究。通过测量血清无维生素K诱导蛋白（PIVKA）-II和未羧化骨钙素（ucOC）水平，分别作为肝脏和骨骼维生素K缺乏的敏感标志物，对37名老年机构居住者的维生素K状态进行了评估。血清PIVKA-II和ucOC水平及其括号中的临界值分别为20.2±8.9 mAU/mL（28 mAU/mL）和4.7±3.0 ng/mL（4.5 ng/mL）。维生素K的摄入量中位数约为200μg/天，这比目前日本的AI高出3倍多。维生素K摄入量与血清PIVKA-II和ucOC/OC水平显著相关，但与血清ucOC水平无关。虽然血清ucOC水平通常是维生素K状态的良好指标，但多元回归分析显示，骨转换标志物升高对血清ucOC水平有显著影响。所有受试者维生素K摄入量均超过维生素K的AI。然而，分别有14%和43%的受试者血清PIVKA-II和ucOC浓度超过临界值。目前的研究结果表明机构居住的老年人骨骼健康需要高于当前AI的维生素K摄入量。
