Except during the summer months, the skin makes little if any vitamin D from the sun at latitudes above 37 degrees north (in the United States, the shaded region in the map) or below 37 degrees south of the equator. People who live in these areas are at relatively greater risk for vitamin D deficiency.
关键取决与你所在地区纬度关系。
Latitude and vitamin D production in the skin
Except during the summer months, the skin makes little if any vitamin D from the sun at latitudes above 37 degrees north (in the United States, the shaded region in the map) or below 37 degrees south of the equator. People who live in these areas are at relatively greater risk for vitamin D deficiency.
https://www.health.harvard.edu/staying-healthy/time-for-more-vitamin-d#:~:text=Except%20during%20the%20summer%20months,risk%20for%20vitamin%20D%20deficiency.
年度检查，医生打电话给我说咋回事，为什么钙的指数低了， 你是不是没服钙片？
呵呵果然如此。就这次后再也不能小看VD 钙片。
未達標準，才聽醫生建議開始食補充品
2者间有个曲线关系，紫外线必须达到一定强度，可实际上真在够高紫外线强度下 暴晒+足够时间，同时又会晒伤和带来其它相应风险。。这之间利与弊。。。
给你看看这个：协和医院骨科专家张嘉，讲骨质疏松，牛奶日晒，补钙和VD，K2关系
https://m.sg.weibo.com/user/phoenixqbzh/4548430519080874
肠道粘膜吸收钙离子实际上是限制吸收速度的，补钙过多没法吸收反会造成消化问题，便秘等， VD有助钙的吸收并进入血液，可血液中血钙又只有一小部分能顺利沉淀到骨头里，血钙多余部分沉积在血管壁，就会有动脉硬化等风险，而补钙想有效，骨头硬，还需要借助K2，K2有助血管里血钙 进入骨头里。。