Vitamin D deficiency has received wide attention and many doctors now check for this deficiency during routine check-ups. I’ve posted about the importance of vitamin D in migraine headaches and for general health. Vitamin D deficiency seems to increase the risk of cancer, other serious diseases and death.
However, just like with vitamin B12 and magnesium, the regular blood test for vitamin D can be misleading. It appears that while blacks have lower levels of vitamin D than whites, they have healthier bones. A study by R. Thadhani of Massachusetts General Hospital explained this paradox. It appears that some of vitamin D circulates in the blood in a free form, while the rest is bound to protein. Only the free form is active, but the blood test measures only the total amount of vitamin D. Blacks appear to have much less of the protein-bound vitamin D, so the amount of the active form can be higher in blacks even if the overall amount of vitamin D is lower. These researchers are developing a more sensitive test for vitamin D levels.
To be on the safe side, most people should aim to have their vitamin D level at least in the middle of normal range. The normal range is 30 to 100 and some studies (for example, in multiple sclerosis) suggest that the higher the level (within the normal range), the better. So, I would recommend getting your level up into the 40s and 50s. Many multivitamins, calcium with vitamin D products, and plain vitamin D supplements have only 200 or 400 units of vitamin D (it is usually listed as vitamin D3). I have seen many patients who need to take 2,000 or even 5,000 units daily to have a good level in the blood. In severe deficiency that does not respond to even these amounts, I prescribe 50,000 units of vitamin D weekly, which is available only by prescription. Unfortunately, unlike with magnesium or vitamin B12, vitamin D is not available in an injection.
The bottom line is that if you are taking a supplement, it does not necessarily mean you have enough of vitamin D in your blood and you should have the test repeated.
