Mg is essential in the metabolism of vitamin D, and taking large doses of vitamin D can induce severe depletion of Mg. Adequate magnesium supplementation should be considered as an important aspect of vitamin D therapy.
Vitamin D screening assay is readily available, but the reported lower limit of the normal range is totally inadequate for disease prevention. Based on the epidemiologic studies, ∼75% of all adults worldwide have serum 25(OH)D levels of <30 ng/mL. Because of the recent increase in global awareness, vitamin D supplementation has become a common practice, but Mg deficiency still remains unaddressed. Screening for chronic magnesium deficiency is difficult because a normal serum level may still be associated with moderate to severe deficiency. To date, there is no simple and accurate laboratory test to determine the total body magnesium status in humans.
