> Shouldn't this problem show up in a much larger portion of the population?
Casual awareness of studies on this suggest that it DOES show up but the symptoms (lowered immune function, seasonal depression, bone issues) are generic and subtle enough to fly under the radar.
It is not helped that, in my experience, many US health plans do not cover the cost of vitamin D testing without a diagnosis of deficiency (which generally requires a test). While that cost is usually low it does mean that it tends not to be offered because practices tend to avoid non-covered procedures for administrative and billing reasons-- you have to actually ask your physician to do the test.
My understanding is that it is somewhat difficult to end up at serum levels of vitamin D that create actual problems, so in general my not-medical-advice suggestion would be to ask your physician about taking a supplement: they're cheap and if everyone took them it is likely population-level health would improve, and it may dramatically improve your QoL particularly in winter months.
Casual awareness of studies on this suggest that it DOES show up but the symptoms (lowered immune function, seasonal depression, bone issues) are generic and subtle enough to fly under the radar.
It is not helped that, in my experience, many US health plans do not cover the cost of vitamin D testing without a diagnosis of deficiency (which generally requires a test). While that cost is usually low it does mean that it tends not to be offered because practices tend to avoid non-covered procedures for administrative and billing reasons-- you have to actually ask your physician to do the test.
My understanding is that it is somewhat difficult to end up at serum levels of vitamin D that create actual problems, so in general my not-medical-advice suggestion would be to ask your physician about taking a supplement: they're cheap and if everyone took them it is likely population-level health would improve, and it may dramatically improve your QoL particularly in winter months.