Sunshine is more than just a source of VitD.
UVA has also been shown to lower blood pressure. This is probably the result of UVA causing the release of nitric oxide from skin stores, which promotes widening of blood vessels. It also acts as an antioxidant to prevent damage to cells.
People who don’t get enough sunlight have altered cellular defense mechanisms that predispose them to excessive inflammation, which can result in autoimmune diseases.
One could argue you can supplement to replace VitD, but are you supplementing your children? From what age? How regularly? What's the quality of the supplementation? How do the poor maintain access to supplementation?
Then you run into the problem that long term, large(r) doses of Vitamin D causes kidney problems.
A study ( https://pubmed.ncbi.nlm.nih.gov/21430082/) found an association between low vitamin D levels and the development of type 2 diabetes. For every ten-unit decrease in blood vitamin D levels, we found a 10% increased risk of developing this form of diabetes over the following five years. when they gave supplements of vitamin D to patients with low vitamin D levels who were already at risk of developing diabetes, there was no overall improvement in their sensitivity to insulin. Nor was there a change in their blood glucose levels compared with those given inactive tablets.
I'm betting, not just in this case, but the act of your body making it's own VitaminD creates benefits we are not yet aware - that oral consumption of a pill isn't going to compensate for.
nevermind MOST of VitaminD pills use soybean oil or some other horrible Omega-6 ridden, cheap seed oil as it's delivery method.
Outside time in the sun is helpful in ways not tied to VitD, as well. circadian rhythms are regulated by bright light exposure. You can't get these lumens by waking up and sitting inside all day. The heat from the sun is capable of reducing physical stresses on the body’s cells and by increasing heat production.
Another important potential effect of sunlight is UV-induced suppression of the body’s immune system. Solar radiation does this by altering the activity of the white cells involved in turning on the body’s defence mechanisms. This may seem like a negative, but it's vital for people to reduce inflammation and when considering how the earth's population spreads out autoimmune disorders (higher percentages the more you get away from the equator), this may be a secondary factor on top of VitaminD.
IMHO -
people need to find a balance with sunscreen and sunshine. if you know you're going to risk a burn, put it on and reapply when necessary.
if you're worried about cancer, eat some cruciferous vegetables regularly to make sure you get lots of sulforaphane which protects against skin cancer. Get regular derma checkups.
but when looking at auto-immune issues (that once you have one, your supplementation isn't going to undo it), the depression issues, and so forth - isn't worth skipping out on sunshine.
Skin cancer may be the most preventable but it's also a fairly unlikely cancer, as far as cancers go - and while it's one of the scarier cancers, catching it early with derma appointments is key to survival. Catching it early has a high survival rate.
An auto-immune issue, on the other hand, will shorten your life and make you suffer along the way, increasingly, for the rest of your life. It's not just a death sentence. It's a slow-slog through hell on the way there. Most people never go into a permanent remission of Ankylosing spondylitis or MS. It just slowly destroys you, it handicaps you, and then it kills you. And along with all that suffering, is your kids, parents and partners suffering right along with you. Yay - therapy sessions for everyone.
It's not just auto-immune issues. Depression, anxiety, even certain cancers themselves all have some relation to low vitamin d.
IMHO - sunlight needs to have it's saturated-fat moment where we realize that a lot of the fear mongering simply wasn't warranted. And that the cures for some diseases end up being the catalyst for many others that are far more likely.
How many people are afflicted with an autoimmune issue? how many with debilitating depression? Compare those numbers to skin cancer. Compare the deaths. Compare the suffering.
Then try to find a balance.