Nice background from the Pharmazeutische Zeitung (German. Use deepl.com for translation). “Among other things, it is disputed whether the “sun vitamin”, apart from bone health, is also important for the prevention and treatment of other common diseases, such as diabetes. (…)It is important to remember: prolonged sunbathing does not help at all and the application of sunscreens with a high sun protection factor (SPF) is counterproductive for vitamin D production. From SPF 14 on, nothing works at all.
