How much vitamin d does a healthy person need ?

一个健康的人到底需要多少维生素d呢？

Can vitamin d replace flu shots ?

维生素d可以取代流感疫苗吗？

Doctors are learning that vitamin d has many health benefits .

医生认识到维生素d对健康有很大的好处。

Teenagers are also at risk for vitamin d deficiency .

十几岁的青年人同样也受到维生素d缺乏的威胁。

Most vitamin d is made when skin is exposed to sunlight .

如果让皮肤晒晒日光则可以产生大量的维生素d。