There are two types of Vit D.
1) Vitamin D3 produced in the skin of humans and other animals, from 7-dehydrocholesterol (derived from cholesterol) by the action of UVB rays.
2) Vitamin D2 , which is produced in plants, fungi and yeasts by solar irradiation from ergosterol.
Both vitamin D compounds cannot be used by our body. When absorbed, they have to be transformed to produce various compounds (their metabolites), which are active and responsible for the multiple functions of vitamin D in the body.
The first biologically active metabolite is 25-hydroxyvitamin D [25(OH)D] (calcidiol), which is produced in the liver from both forms, vitamin D 2 or D 3.
This is precisely the parameter 25-hydroxyvitamin D [25(OH)D] that is measured in analyzes to see Vit D levels.
But traditionally, levels of this vitamin have been considered normal to be between 15 and 25 ng/ml, but this does not mean that these data are optimal. It is just the level that shows a normal distribution in a modern society in which most people do not get enough time in the sun daily or consume foods rich in this vitamin.
Recently, field studies have been carried out on people who live exposed to the sun - just as our ancestors did - such as farmers, lifeguards, athletes who train outdoors and it was observed that their levels exceeded 40 ng/ml, reaching optimal levels of between 60-90 ng/ml.
Try to have high levels and supplement if necessary.
Vit D is too important.