Institute of Sport and Health, Victoria University, Melbourne 3011, Australia.
Australian Institute for Musculoskeletal Sciences (AIMSS), Melbourne 3021, Australia.
Nutrients. 2019 May 17;11(5):1097. doi: 10.3390/nu11051097.
Supplementation with vitamin D helps to alleviate weakness and fatigue seen with deficiency. However, large bolus doses appear to worsen the risk of falls. Whether this occurs as a direct result of muscle weakness is currently unknown. Thus, the aims of this study were to examine the muscle function following administration of high doses of vitamin D. Given the safety issues associated with bolus doses, experiments were conducted on C57BL6 mice. Mice at eight weeks of age with otherwise normal levels of vitamin D were supplemented for four weeks with a high dose (HIGH; = 12) of vitamin D (20000 IU/kg food) designed to provide a year's worth of vitamin D. These mice were compared to another group who received that same yearly dose in a single bolus i.p. injection (YEAR; = 12). Mice provided with standard mouse chow, which contained 1000 IU/kg food, and injected with the vitamin D vehicle were used as controls (CON; = 16). Force and fatigue properties of hind limb fast- and slow-twitch muscles were measured. CON animals ingested vitamin D consistent with typical human supplementation. HIGH animals consumed significantly more food than the CON animals, such that they ingested more than a year's worth of vitamin D in four weeks. Despite this, there were few differences in the muscle function compared with CON. YEAR animals demonstrated lower absolute and relative forces in both muscles compared to the HIGH animals, as well as lower force during fatigue and early recovery. Large bolus doses of vitamin D appear to have detrimental effects on the skeletal muscle function, likely being a contributor to increased risk of falls observed with similar doses in humans. Mice ingesting the same amount over four weeks did not demonstrate the same deleterious effects, suggesting this may be a safe way to provide high vitamin D if required.
补充维生素 D 有助于缓解因缺乏而导致的虚弱和疲劳。然而，大剂量冲击治疗似乎会增加跌倒风险。目前尚不清楚这种情况是否是由于肌肉无力直接导致的。因此，本研究旨在研究大剂量维生素 D 给药后肌肉功能的变化。鉴于大剂量冲击治疗存在安全问题，本实验在 C57BL6 小鼠上进行。8 周龄的小鼠，维生素 D 水平正常，补充高剂量（HIGH；n=12）维生素 D（20000 IU/kg 饲料），旨在提供一年的维生素 D。将这些小鼠与另一个接受相同年剂量单次腹腔注射（YEAR；n=12）的组进行比较。给予标准鼠粮（含 1000 IU/kg 饲料）且注射维生素 D 载体的小鼠作为对照（CON；n=16）。测量后肢快肌和慢肌的力量和疲劳特性。CON 组动物摄入的维生素 D 与典型的人类补充剂量一致。HIGH 组动物摄入的食物量明显多于 CON 组，以至于它们在 4 周内摄入了超过一年的维生素 D。尽管如此，与 CON 组相比，它们的肌肉功能差异很小。与 HIGH 组相比，YEAR 组的两群动物的绝对和相对力量均较低，且疲劳和早期恢复期间的力量也较低。大剂量的维生素 D 冲击治疗似乎对骨骼肌肉功能有不良影响，这可能是类似剂量的维生素 D 对人类跌倒风险增加的原因之一。在 4 周内摄入相同剂量的小鼠没有表现出同样的有害影响，这表明如果需要，这种方法可能是提供高剂量维生素 D 的安全途径。
