From what I can tell the article lists guidelines based on consumption (how much Vit D to take or what is recommended), but seems to fail to mention that absorp

From what I can tell the article lists guidelines based on consumption (how much Vit D to take or what is recommended), but seems to fail to mention that absorption can vary by person. I think the better method would be to get a blood test and find out where you are and supplement (or get more sun) as needed to bring levels within normal to optimal ranges. But again, what is normal or optimal? Where is the mention of Vit K? In my experimentation, it takes about 5000-10,000 IU per day supplementation + outdoor sun exposure 3 days a week for about an hour each day for me to be in the (or what I am hoping is) normal/optimal range (around 60-70 ng/mL). My sun exposure in that hour is hiking outdoors in full/partial sun mid-day with no shirt on. So 75% body exposure I guess? I am assuming that normal or optimal is mid to upper values in the lab results ranges for Vit D. In the case of Labcorp, the range referenced was 30-100 ng/mL with anything around 30ish and under being definitely deficient according to the lab results description of the range. So in my case it does take quite a bit of sun + supplementation to get optimal. Now my results above are based on summer sun exposure. In the winter, obviously that will be reduced (colder less outdoor skin exposure + sun is low in the sky) so I'm curious to see what difference I see on the labs without the sun exposure part. There are some nice phone apps that helpful in figuring out sun exposure and Vit D. I have used D Minder on the iPhone. You punch in some stats about yourself (skin type, age, % of skin exposure and it asks you a few questions to confirm skin type based on your experience in the sun (do you burn easily, just get red and tan, just tan etc). Then based on your current geo location, sun angle in the sky (winter vs summer and the time of day) and time you want to spend exposed to the sun it calculates Vit D absorption in IU. Granted I'm not sure how accurate it is, but based on my labs and supplementation the biggest eye opener to me was how much sun it really takes to make a difference between deficient and normal/optimal. I do tend to believe now that the old recommendation of "15 min in the sun per day is enough" is false. That might be enough to stave off rickets, but I think more is probably in order for optimal living. However, with all this said it would be great if there more studies on what the optimal or disease preventing blood levels are - with emphasis on blood levels and not just IUs intake per day.