Vitamin D from sunlight. Is it possible (at British latitudes) to get enough thru double glazed windows?
Probably not-
here is Cecil’s answer
You would probably need Californian sunshine to get through double glazing, not our pathetic english sun
Yeah, I read that a little while ago, eburacum45, perhaps that is what got me to thinking about the vit D thing. Rickets, here I come then 
In the nicest possible way: perhaps you should get out more?
You can also buy in-home UV lights for SAD treatment.
jjimm, In the nicest possible way … I’m not S.A.D. I’m livid!
I’m confused. What is it you’re livid (furious) about? Or, are you merely saying you’re livid (pale)? Vitamin D isn’t going to give you a tan. You may get a tan, while attempting to increase your level of Vitamin D production through exposure to sunlight, but there’s no causal relationship, there.
IIRC, Ultraviolet light in the B range (UVB) triggers a reaction in the skin, which produces Vitamin D3. D3 is a proto-vitamin which, when allowed to react with other elements in the body (calcium and phosphorous, I think?), produces normal bone growth. It takes only about five minutes of exposure to produce all the D3 you need, although the time may depend on the intensity of the UVB. How about opening a window for a few minutes, if you can’t get out? You could just take a vitamin supplement, too. They’re less effective, but sufficient to stave off ricketts, I believe.
Tanning is also a reaction to UVA and UVB in the skin, but unrelated to vitamin production.
I’m sure one of the resident doctors will be along to correct me where my memory has gone astray. But, I’m still confused.
Hello Davebear,
I’m furious that fibromyalgia has made my legs pack-up so I can’t get about, especially outside.
The 5 min exposure will work if fully clothed?
What does IIRC mean, please? I have oft wondered that.
Thanx.
Sorry, English Cid - I wasn’t aware of this. My jibe was inappropriate.
IIRC means “If I recall correctly” - i.e. this is from memory, and therefore may be slightly off.
Hey, no probs, jjimm 
I’m from the misistry of silly walks.
I meant miNistry.