The paper Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis in the Open Heart journal is a recommended read.
Abstract: There are two types of nutrient deficiencies, frank deficiencies (such as scurvy from ascorbic acid deficiency or goitre from iodine deficiency) and subclinical deficiencies (a clinically silent reduction in physiological, cellular and/or biochemical functions). It is the latter that is most concerning as it is hard to diagnose and predisposes to numerous chronic diseases.
Because serum magnesium does not reflect intracellular magnesium, the latter making up more than 99% of total body magnesium, most cases of magnesium deficiency are undiagnosed. Furthermore, because of chronic diseases, medications, decreases in food crop magnesium contents, and the availability of refined and processed foods, most people in modern societies are at risk for magnesium deficiency.
Certain individuals will need to supplement with magnesium to prevent suboptimal magnesium deficiency, especially if trying to obtain an optimal magnesium status to prevent chronic disease. Subclinical magnesium deficiency increases the risk of numerous types of cardiovascular disease, costs nations around the world an incalculable amount of healthcare costs and suffering and should be considered a public health crisis. That an easy, cost-effective strategy exists to prevent and treat subclinical magnesium deficiency should provide an urgent call to action.