Some important factors on receiving Vitamin D from sun exposure are skin color, the amount of clothing you wear & time of day.
Light skin absorbs more than dark skin. Noon gives more Vitamin D than morning or evening. Sun screen & sun screen lotion limit the Vitamin D you get.
Being a fellow northerner, walking outside doesn't do much in the winter when 95% of my body is covered in clothing.
Science Vs did a great podcast on this - https://gimletmedia.com/episode/vitamins-supplements-worth/ (Vitamin D is their first supplement they discuss & the link provides a transcript for skimming)
My personal experience (with no medical background except the Chiropractor's wife who recommended it) finds that Vitamin D supplements (5,000 IU) seems to help prevent & shorten colds & flu-like bugs. I mostly take that dosage when feeling slightly ill or run down.
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.
I do have extremely pale skin, but I yeah, a lot of it ends up covered in the winter.
Even if you were naked it wouldn’t help, the sun would be too low.
The major advantage here is cost of living is so much lower than the valley. Housing is cheap, which leaves a lot of room for money to use to eat out, nightlife, plays, music, etc.
Vitamin D defficiency is really a problem, I didn't know I had it till I got a blood test. I was feeling tired all the time, my bones ached, I felt low, dizzy, etc. Getting Vitamin D supplements helped cured all the symptoms, I feel much healthier now.
Of course, when it comes to fish, and especially with concern to mercury, over-doing it is very possible.
For anyone who understands Swedish this presentation is valuable: https://youtu.be/syRaJVIBNnw Article with the same info: http://www.lakartidningen.se/OldWebArticlePdf/6/6279/LKT0711...