4 ms·

Does it means that those studies that says most people of color in northern hemisphere are vitamin-D deficient not that strongly substantiated? I though people

• tzs 6y ago
  Skin pigmentation does affect vitamin D production. There are a few stages between production of vitamin D and the delivery of useful vitamin D to the places where it is needed. The form produced by the skin is not the form needed, so it has to be transformed. The usual test measures vitamin D levels at a particular stage, and then we infer that if the levels are normal at that stage, they will be normal at the final stage too. The problem seems to be that this was calibrated based on the levels in light skinned people, and it is starting to look like the relative levels at the different stages are different in darker skinned people. Think of it not as a dark skinned person's skin produces less than a light skinned person's skin, but rather the light skinned person's skin produces more than the dark skinned person's skin. Their bodies both need the same amount of the final form, and both are able to convert enough to that form, and don't bother converting much more than they need. The result is that the light skinned person has more leftover pre-conversion form. The test measures that pre-conversion form.