Magnesium is second only to potassium in abundance as an intracellular cation. The whole body of a human adult contains nearly 25 gm. The numerous important biochemical reactions dependent upon the presence of this metal have been discussed elsewhere. Magnesium is an essential nutrient for animals and plants, suggesting that a dietary inadequacy of this ion might readily result in deficiency disease. Indeed, such deficiency states have been induced in animals. Tetany and convulsions, subsequent to experimental magnesium deficiency, were first shown to occur in rats, in 1932, and later in many other animal species.

VALLEE BL, WACKER WE, ULMER DD. The magnesium-deficiency tetany syndrome in man. N Engl J Med. 1960 Jan 28;262:155-61. doi: 10.1056/NEJM196001282620401. PMID: 13840893.