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维生素D "阳光维生素"

分类: 英语科普 

多年前,科学家就发现晒太阳可以补充维生素D。当人体皮肤表层的7-脱氢胆固醇遇到阳光里的紫外线后,就会生成这种维生素。人体内源性维生素D约80%在皮肤表皮合成,仅20%从食物中摄取,所以维生素D也被称为"阳光维生素"。

The connection between sunlight and bone health was made over 200 years ago when a Polish doctor treated inner city children with rickets (or soft bones) by taking them to the countryside for the summer months. In fact, vitamin D promotes heart, metabolic, and immune system health in addition to supporting bone health.

200多年前,当一位波兰医生带着患有佝偻病(或软骨头)的城市儿童去乡下避暑时,发现了阳光与骨骼健康之间的联系。事实上,维生素D除了有益骨骼健康外,还对心脏、新陈代谢和免疫系统健康有益。

Vitamin D is absorbed into our bloodstream and converted to the active form (a secosteroidal hormone) and a storage form (25-hydroxyvitamin D) – it functions more like a hormone than a vitamin. So, it is no surprise that having sufficient levels of vitamin D is so important for a broad array of health effects.

维生素D被血液吸收,并转化为活性形式(一种开环甾体激素)和储存形式(25-羟基维生素D)——其功能更像是一种激素而不是维生素。因此,充足的维生素D对健康有着重要影响。

Potential benefits associated with vitamin D include:

维生素D的潜在健康益处包括:

Aids in calcium absorption for maintaining strong bones and teeth

促进钙吸收,保持骨骼和牙齿强健

Helps support healthy heart and immune function

有益心脏健康和增强免疫功能

Facilitates healthy cell development

促进健康的细胞发育

值得注意的是,只有裸露的皮肤接受太阳光照射的时候才能产生维生素D。因此,冬天更需要多晒太阳,才能补充充足的维生素D。

晒太阳的时间需要多久?

冬春季,将面部和双上臂暴露于阳光下 10~30 分钟,夏季由于紫外线较强,裸露部位较多,接受太阳直射 5~10 分钟,每周 2~3 次就能让身体产生足够的维生素 D。绝大多数人每天在阳光下晒 10 至 20 分钟即可。

隔着玻璃晒太阳有效吗?

隔着玻璃晒太阳会大大降低效果,因为中波紫外线 UVB 的穿透性比较差。在家中隔着玻璃晒太阳几乎是无效的,因为中波紫外线的透过率会大幅度降低,从而影响人体合成维生素 D。晒太阳的最佳地点是户外,因各种原因必须在室内晒太阳,也一定要打开窗子,让阳光直接与皮肤接触。

"Vitamin D is produced when sunlight touches our skin, and very few foods in nature contain vitamin D, with fortified foods – primarily cow's milk – being responsible for most of the vitamin D in the American diet," said Jamie McManus, Shaklee's Chair of Medical Affairs. "As daylight savings time ends, we have less opportunity to absorb vitamin D through sunlight. Therefore, people should supplement their vitamin D intake, especially during winter."

美国营养品公司嘉康利医学事务主席杰米·麦克马纳斯称:“当阳光照射皮肤时,人体就会产生维生素D,自然界中含有维生素D的食物较少,而牛奶是美国人饮食中维生素D的主要来源。随着夏令时间结束,通过阳光吸收维生素D的机会减少。因此,人们应该补充维生素D摄入量,尤其是在冬季。”

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