Originally Posted by ambereva
This thread is interesting. Seems like alot of poeple are D deficient? I had all my blood levels checked a couple months ago after being on a whole foods vegan diet for a year and everything was perfect. My D was 47. My A, iron, calcium, B12 and folate were all perfect too. I don't take any supplements. I eat a TON of fresh fruits and vegetables and try to get some sun every day.
What is the theory as to what's causing D deficiency?
For me, I think it's been part of a slow build-up of health issues from my childhood, and I tend to see a lot of people with chronic, sometimes complex health issues being at the really low end of the scale. Starting by growing up in the Pacific Northwest didn't help, and I think environment alone can be enough for quite a few people, but I think bigger factors were more significant long-term for me.
I think liver function may play a role, at least that's my guess as to part of it--not the kind of liver function that flags as bad on a blood test, even I passed that, but more subtle issues. My cholesterol dropping way down didn't help (cholesterol is closely related to the chemical in our bodies that sunlight changes into vitamin D), but I think I was low in D before--that just compounded the issue, so that I probably wasn't making as much as most white people living in Texas. So I'm not comfortable relying on environmental exposure alone, I like the belt and suspenders approach of the WAPF, especially for things like A and D.
Overall, for a lot of nutrients, blood tests ranges seem pretty wide, maybe you already know that, I didn't until fairly recently. It often seems to be that it's only a subset of the normal range that's best for people to actually be healthy. Or like the blood retinol test--my understanding is that if you're out of range, you're definitely low, but if you're in range, it doesn't say much.
So I think sometimes it can be fairly simple and straightforward, but sometimes it's tied into more complex issues--that IMO are often intertwined with multiple nutrient deficiencies, not just D.