I also like this post:
Dr Vieth has a model of tissue 1,25(OH)2D synthesis and degradation in which the level of active substance is pretty well independent of blood vitamin D level, provided the level is either rising or stable.
Basically, testing your blood for vitamin D is a complete waste of effort as it gives no indication of how much available vitamin D is in your tissue.
..and there's more to it than sun exposure.
From all of this I would deduce that, under marginal levels of UVB in Glasgow, the primary determinant of gross clinical expression of deficiency of vitamin D is vegetarianism. There is a protective effect of meat consumption.</blockquote>
It seems like humans can get away with vegetarianism in the tropics. Move north and you need to eat meat.
The "Seven Deadly Sins"
Grains (wheat/rice/oats etc) . . . . . Dairy (milk/yogurt/butter/cheese etc) . . . . . Nightshades (peppers/tomato/eggplant etc)
Tubers (potato/arrowroot etc) . . . Modernly palatable (cashews/olives etc) . . . Refined foods (salt/sugars etc )
Legumes (soy/beans/peas etc)