Cannell J J, Hollis B W, Zasloff M, Heaney R P
Atascadero State Hospital, 10333 El Camino Real, Atascadero, California 93422, USA.
Expert Opin Pharmacother. 2008 Jan;9(1):107-18. doi: 10.1517/14656566.9.1.107.
The recent discovery--in a randomised, controlled trial--that daily ingestion of 1100 IU of colecalciferol (vitamin D) over a 4-year period dramatically reduced the incidence of non-skin cancers makes it difficult to overstate the potential medical, social and economic implications of treating vitamin D deficiency. Not only are such deficiencies common, probably the rule, vitamin D deficiency stands implicated in a host of diseases other than cancer. The metabolic product of vitamin D is a potent, pleiotropic, repair and maintenance, secosteroid hormone that targets > 200 human genes in a wide variety of tissues, meaning it has as many mechanisms of action as genes it targets. A common misconception is that government agencies designed present intake recommendations to prevent or treat vitamin D deficiency. They did not. Instead, they are guidelines to prevent particular metabolic bone diseases. Official recommendations were never designed and are not effective in preventing or treating vitamin D deficiency and in no way limit the freedom of the physician--or responsibility--to do so. At this time, assessing serum 25-hydroxy-vitamin D is the only way to make the diagnosis and to assure that treatment is adequate and safe. The authors believe that treatment should be sufficient to maintain levels found in humans living naturally in a sun-rich environment, that is, > 40 ng/ml, year around. Three treatment modalities exist: sunlight, artificial ultraviolet B radiation or supplementation. All treatment modalities have their potential risks and benefits. Benefits of all treatment modalities outweigh potential risks and greatly outweigh the risk of no treatment. As a prolonged 'vitamin D winter', centred on the winter solstice, occurs at many temperate latitudes, < or = 5000 IU (125 microg) of vitamin D/day may be required in obese, aged and/or dark-skinned patients to maintain adequate levels during the winter, a dose that makes many physicians uncomfortable.
近期在一项随机对照试验中发现，在4年时间里每日摄入1100国际单位的骨化醇（维生素D）可显著降低非皮肤癌的发病率，这使得治疗维生素D缺乏症在医学、社会和经济方面的潜在意义无论怎样强调都不为过。维生素D缺乏不仅很常见，甚至可能是常态，它还与许多除癌症之外的疾病有关。维生素D的代谢产物是一种强效、具有多效性、用于修复和维持的甾醇类激素，它作用于多种组织中的200多个人类基因，这意味着其作用机制与所作用的基因数量一样多。一个常见的误解是，政府机构制定目前的摄入量建议是为了预防或治疗维生素D缺乏症。事实并非如此。相反，这些建议是为了预防特定的代谢性骨病。官方建议从未旨在预防或治疗维生素D缺乏症，也无法有效做到这一点，而且绝不限制医生进行此类预防或治疗的自由或责任。目前，检测血清25-羟维生素D是进行诊断以及确保治疗充分且安全的唯一方法。作者认为，治疗应足以维持生活在阳光充足环境中的人群体内的维生素D水平，即全年大于40纳克/毫升。有三种治疗方式：阳光照射、人工紫外线B辐射或补充剂。所有治疗方式都有其潜在的风险和益处。所有治疗方式的益处都超过潜在风险，且大大超过不进行治疗的风险。由于许多温带地区会出现以冬至为中心的漫长“维生素D冬季”，肥胖、年老和/或肤色较深的患者在冬季可能需要每天摄入≤5000国际单位（125微克）的维生素D以维持足够水平，这一剂量让许多医生感到不安。
