维生素 D 是维持人体骨骼健康不可或缺的脂溶性维生素，很多人只知道补钙，却常常忽略维生素 D 的关键作用。单纯补充钙质，如果缺少足够的维生素 D，钙很难被肠道吸收进入血液，大部分钙会直接随粪便排出体外，补钙效果大打折扣。维生素 D 如同钙的 “搬运工”，负责促进肠道对钙、磷的吸收，调节血液当中钙磷浓度，为骨骼矿化提供充足原料。
Vitamin D is an essential fat-soluble vitamin for human bone health. Many people focus only on calcium supplementation while overlooking the critical role of vitamin D. Without adequate vitamin D, calcium can hardly be absorbed by the intestine, and most of it passes out of the body directly, making calcium supplementation inefficient. Acting like a “transporter” for calcium, vitamin D boosts intestinal absorption of calcium and phosphorus, regulates their concentration in blood, and supplies raw materials for bone mineralization.
人体获取维生素 D 主要有两种途径：一是皮肤接受阳光中紫外线照射合成，二是通过食物摄入。日常饮食当中，深海鱼类、蛋黄、动物肝脏含有少量维生素 D，天然食物能够提供的维生素 D 十分有限。现代人群室内工作时间长、防晒普及，单纯依靠日晒与普通饮食，很容易出现维生素 D 不足。
Human bodies obtain vitamin D in two main ways: synthesis triggered by ultraviolet sunlight on skin, and intake from food. Limited vitamin D can be found in deep-sea fish, egg yolks and animal livers, and natural food sources provide only small amounts. Due to long indoor hours and widespread sunscreen use, modern people are prone to vitamin D insufficiency even with regular diet and occasional sun exposure.
维生素 D 长期缺乏会带来一系列骨骼问题。儿童时期缺乏，会阻碍骨骼正常钙化，诱发佝偻病；成年人缺乏，会造成骨量流失加快，骨密度下降，提升骨质疏松与骨折的发生风险，同时还可能伴随肌肉无力、肢体酸痛，进一步增加跌倒风险。中老年群体、孕期女性、长期少晒太阳的人群，是维生素 D 缺乏的高发群体。
Long-term vitamin D deficiency leads to multiple bone disorders. In children, it impedes normal bone calcification and causes rickets. In adults, it accelerates bone loss, reduces bone mineral density, and raises risks of osteoporosis and fractures. It may also bring muscle weakness and body soreness, further increasing fall risks. Middle-aged and elderly people, pregnant women, and those with limited sun exposure are high-risk groups for vitamin D deficiency.
但维生素 D 并非补充越多越好，过量摄入会造成维生素 D 中毒，引发血钙升高，甚至损伤肾脏与血管，不建议自行大剂量服用补充剂。应当结合血清 25‑羟维生素 D 检测结果，在医生指导下合理补充。配合适度户外活动、均衡膳食，让维生素 D 充分发挥作用，筑牢骨骼健康的基础。
Nevertheless, more vitamin D does not equal better health. Excessive intake may result in vitamin D intoxication, high blood-calcium level, and damage to kidneys and blood vessels. High-dose supplements should not be taken without medical advice. It is recommended to test serum 25-hydroxyvitamin D and take supplements under professional guidance. Combined with proper outdoor activities and balanced diet, vitamin D can effectively protect skeletal health.