- 1,980
- 5,581
Normal vit D level is around 70, as per studies on savage tribes. 40 is decent but most certainly suboptimal. A lot of studies show benefits above 40. When you think about it, 15 minutes of sun cannot be optimal considering how much time our ancestors spent outside. 15 minutes is enough so that you don't end up in ICU when you catch covid or the flu, but that's it.
I haven't gone too deep into the tribal studies, but I don't know if they can be directly extrapolated to modern humans (at least without a lot of caution) given that there seems to be (a) very wide racial/regional variation in Vitamin D plasma concentration, (b) people generally didn't live as long then, so they didn't have the chance to start exhibiting any potential effects from overexposure, and (c) we would need to weigh the benefits of more sun exposure against the increased risk of melanoma. In an East Asian/Han population, high vitamin D seems to correlate with heightened esophageal cancer risk, in blacks, with CAD. It reminds me a bit of how we usually recommend two different types of meds for blood pressure in blacks vs whites (generally a diuretic as the first line in blacks; ACE/ARB as the first line in whites).
Really cool how even simple things like nutrition can vary so widely between races.