Please read this :
People all vary in how they utilize nutrients. Drug use can also lower nutrients in the body (this is how many side effects manifest).
This new DNA test is almost here:
We are not all identical in how our bodies function.
Vitamin levels are sometimes misleading. They may show only what is in the serum and not what is being used
within the cells. The new Vitamin testing involves genetic flaws in vitamin use, and are not affected
by what you are taking. I think this new testing is very exciting, and may provide an increased quality of
life for many people plagued with vague and idiopathic or hard to diagnose conditions.
Most misleading are levels for some of the Bs and magnesium. Right now we don't have long term data on
the Vit D issue, but it is looking like we can trust those blood levels so far.