Macca,
I don't want to be rude, and hardly know the exact science, but I suspect getting 20min of sunlight exposure will always bet a pill in a bottle.
I subscribe to the idea that sunlight is necessary for our immune system to be robust, that is how we evolved of 10,000's of years.
Not rude at all, we are here to discuss things not to lecture (well most of us)
I agree about sunshine, in days gone by most of the well respected hospitals had areas where people were wheeled out each day to sit in the sun.
Sanitariums for the chronically ill always had lawns and gardens, there are many photos showing convalescing servicemen and women after the wars all sitting out in the sun.
The problems started when we all moved indoors and the Slip Slop Slap campaign became the norm, there are many children today that are actually Vit D deficient which is not surprising.
When I was a kid we left home after breakfast with the instruction to be home before dark, we were always in the sun.
I am paying for that now, ATM I have 10 stitches in me where I have had two sun spots cut out. Two months ago exactly the same thing, so my kids see me getting these things frozen and cut every year and cover my grandkids up to prevent it.
It is a balancing act, Doctors are actually saying that the SSS campaign is too effective and needs to be wound back a bit.
I think that Vitamin D should be tested when people get their annual blood tests, if it is below 50 then buy a bottle of D3.
Consider the damage to the economy every winter with colds and flu, if everyone was aware of the importance of Vit D they could be sure to get some sun exposure in Autumn to build it up or simply get into the Vit D pills.
I used to get a cold in April/May and sniffle my way through the winter until the hot days started, a bit of sunshine and I would get better.
I stopped going in the sun because of my many skin problems so now I have to supplement my Vit D and I have not had a cold for the 10 years that I have been taking it