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Vitamin and Supplements
Research shows how important it is to know if you are vitamin D deficient. Vitamin D deficiency can cause a variety of health problems, found recently in studies. The best way to know if you have a vitamin D deficiency is by asking your doctor for a 25-hydroxy vitamin D test. Normal levels of vitamin D in the blood are 30.0 to 74.0 nanograms per milliliter (ng/mL), but there is ongoing research about optimal levels.