The Requirement of Magnesium by the Normal Adult

Abstract

The widespread assumption that the average daily intake of magnesium is sufficient to maintain equilibrium in the normal adult has been questioned. Analysis of published metabolic data indicates that the minimal daily requirement is not 220 to 300 mg. per day, as has been reiterated, or even 5 mg. per kg. per day as has also been suggested, but probably at least 6 mg. per kg. per day. The available clinical metabolic data provide evidence that at intakes below 6 mg. per kg. per day, negative magnesium balance is likely to develop, particularly in men. Women seem to retain more magnesium than men at low and marginal magnesium intakes. At intakes above 10 mg. per kg. per day, strong positive magnesium balances develop, which probably reflect repletion of suboptimal tissue stores. High protein, calcium and vitamin D intakes, and alcohol all function to impede retention or to increase the requirement of magnesium, particularly in those on low magnesium intakes. On magnesium intakes above 6 mg. per kg. per day, little interference with magnesium retention by calcium, protein or vitamin D has been reported. The diet in the Orient apparently provides 6 to 10 mg. per kg. per day. The Occidental diet, however, provides an average of 250 to 300 mg. of magnesium daily, or less than 5 mg. per kg. per day for most adults. Because the Western diet is often also rich in protein, calcium and vitamin D, and alcohol ingestion is common, it is suggested that the optimal daily intake of magnesium should be 7 to 10 mg. per kg. per day. The existence of subacute or chronic magnesium deficiency is difficult to diagnose. Because the tissues damaged by magnesium depletion are those of the cardiovascular, renal and the neuromuscular systems, early damage is not readily detectable. It is postulated that long-term suboptimal intakes of magnesium may participate in the pathogenesis of chronic diseases of these systems.