Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease
Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease
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DOI：
10.1093/ajcn/80.6.1678s
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发表时间：
2004-12-01
影响因子：
7.1
通讯作者：
Holick, MF
中科院分区：
文献类型：
--
作者：
Holick, MF
大多数人依靠阳光照射来满足对维生素 D 的需求。太阳紫外线 B 光子被皮肤中的 7-脱氢胆固醇吸收，导致其转化为前维生素 D-3，后者迅速转化为维生素 D-3。季节、纬度、一天中的时间、皮肤色素沉着、衰老、防晒霜的使用和玻璃都会影响皮肤产生维生素 D-3。维生素 D-3 形成后，会在肝脏中代谢为 25-羟基维生素 D-3，然后在肾脏中代谢为其生物活性形式 1,25-二羟基维生素 D-3。维生素 D 缺乏症在美国儿童和成人中是一种未被认识到的流行病。维生素D缺乏不仅会导致儿童患佝偻病，还会促使和加剧成人骨质疏松症，并导致痛苦的骨病骨软化症。维生素 D 缺乏与致命癌症、心血管疾病、多发性硬化症、类风湿性关节炎和 1 型糖尿病的风险增加有关。将 25-羟基维生素 D 的血液浓度维持在 80 nmol/L（类似于 30 ng/mL）以上不仅对于最大化肠道钙吸收很重要，而且对于提供大多数组织中存在的肾外 1α-羟化酶以产生 1,25-二羟基维生素 D-3 也可能很重要。虽然长期过度暴露在阳光下会增加患非黑色素瘤皮肤癌的风险，但避免所有直接阳光照射会增加维生素 D 缺乏的风险，从而产生严重后果。每年监测血清 25-羟基维生素 D 浓度应有助于发现维生素 D 缺乏症。合理的阳光照射（通常每周 2 至 3 次，手臂和腿或手、手臂和脸部暴露 5-10 分钟）以及增加饮食和补充维生素 D 摄入量是保证维生素 D 充足的合理方法。
Most humans depend on sun exposure to satisfy their requirements for vitamin D. Solar ultraviolet B photons are absorbed by 7-dehydrocholesterol in the skin, leading to its transformation to previtamin D-3, which is rapidly converted to vitamin D-3. Season, latitude, time of day, skin pigmentation, aging, sunscreen use, and glass all influence the cutaneous production of vitamin D-3. Once formed, vitamin D-3 is metabolized in the liver to 25-hydroxyvitamin D-3 and then in the kidney to its biologically active form, 1,25-dihydroxyvitamin D-3. Vitamin D deficiency is an unrecognized epidemic among both children and adults in the United States. Vitamin D deficiency not only causes rickets among children but also precipitates and exacerbates osteoporosis among adults and causes the painful bone disease osteomalacia. Vitamin D deficiency has been associated with increased risks of deadly cancers, cardiovascular disease, multiple sclerosis, rheumatoid arthritis, and type 1 diabetes mellitus. Maintaining blood concentrations of 25-hydroxyvitamin D above 80 nmol/L (similar to30 ng/mL) not only is important for maximizing intestinal calcium absorption but also may be important for providing the extrarenal la-hydroxylase that is present in most tissues to produce 1,25-dihydroxyvitamin D-3. Although chronic excessive exposure to sunlight increases the risk of nonmelanoma skin cancer, the avoidance of all direct sun exposure increases the risk of vitamin D deficiency, which can have serious consequences. Monitoring serum 25-hydroxyvitamin D concentrations yearly should help reveal vitamin D deficiencies. Sensible sun exposure (usually 5-10 min of exposure of the arms and legs or the hands, arms, and face, 2 or 3 times per week) and increased dietary and supplemental vitamin D intakes are reasonable approaches to guarantee vitamin D sufficiency.