Everyone should read this article: https://www.outsideonline.com/2380751/sunscreen-sun-exposure-skin-cancer-science

I was already familiar with much of it, but not the link between sun exposure and the production of nitric oxide, which is a very basic and very important part of our biochemistry.

In addition, from reading the article and seeing that sunlight on the skin does more than produce just Vitamin D, I wonder if the failure of clinical studies that show no benefit to supplementing vitamin D in diseases known to be associated with low levels (except for osteoporosis) might be due to the other effects.  As with many things in medicine, what we know is often not the whole story.

While I’m at it, and we are going through a heat wave, please stay hydrated in this weather, and to the extent that you are out in it and perspiring, you need not only water but more salt, potassium, and perhaps some magnesium.  Salt is easy, potassium is found in bananas, other fruits, vegetables and vegetable broths, etc.  If you are eating well magnesium is probably not an issue but it wouldn’t hurt to take 100 mg/daily (if you aren’t already).

Please find standard recommendations for dealing with extreme heat at:  https://www.webmd.com/fitness-exercise/heat-exhaustion  You can assess the recommendation for sunscreen with some caution, based on the article above