I can understand how important this issue is to you! You seem very determined. All one needs to do, is ask his Dr to check Vit D levels with his next blood test. I certainly didn't think, that Vit D was any part of my problem, I walk outdoors 5x a week! Imagine my surprise, when I tested at almost no Vit D in my system! I was started on a super high dose, then I tapered down. My doctor calls me many times a year to tell me I am Vit D deficient!!
Some Dr's are now saying we need much more Vit D, then previously thought. 5-10,000 IU per day 'may'
be a more needed dose.
I am certainly not condoning some 'diet'. But I do believe everyone should check their Vit D levels, and re-check them often, if low on D.