Hello Geoff

I can only write about my own situation. Despite spending as little time as possible in the sun and always wearing UVA & UVB sunblock on my face which is the only part that is normally exposed, I have no problems. A Dexa bone scan revealed a bone density level of a 36 year old ( I am rising 66), I have no calcium or vitamin D deficiency and I am not on Prednisone. I am Caucasian in a Northern European climate. If I were of a darker skinned ethnicity my needs might be greater.
I am advised all the same that it's prudent to takea prophylactic 1500mgs calcium carbonate and 10mcg/400IU's Vitamin D which comes in one chewable tablet. That's the seventh of my daily pill intake and it doesn't bother me one bit.
If I were to try to supplement by dietary intake I wouldn't easily know how much I was taking and as it is my diet is more than adequate in foods containing vitamin D. I do not want or need to be eating more food of any sort! especially the major Vitamin D containing items some of which we do not normally eat, such as liver. I would much rather take a chewy.
Estimates of the amount of sun exposure needed to manufacture enough vary considerably. There's been a lot of publicity lately about Vitamin D deficiencies and disease associations based on the results of various studies. I suspect that the supplement manufacturers have gleefully seized on this and are pushing it to the maximum. Too much Vitamin D can be harmful of course.
Both my lupus expert doctors have said that it is greatly exaggerated even in northern latitudes in winter with miminal time outdoors a person eating a normal well balanced diet should be fine, unless tests show that they do have additional needs for some reason.
The only other supplement I take is a B complex and water soluble so any not used will be excreted.
So, that's my take on the question. I hope you are doing well and coping with the heat OK. It's pretty cold here but I would much rather wear an extra jumper than swelter
Keep up your good work !
Cheers
Clare