American Journal of Clinical Nutrition, Vol 15, 133-143, Copyright © 1964 by The American Society for Clinical Nutrition, Inc.

Experimental Human Magnesium Depletion

I. Clinical Observations and Blood Chemistry Alterations

¹ From the Division of Experimental Surgery and Physiology, and the Andre and Bella Meyer Physiology Laboratory, Sloan-Kettering Institute for Cancer Research, and the Department of Medicine, Memorial and James Ewing Hospitals, New York, New York

Clinical and chemical changes are reported which have occurred in the course of a longterm study on the effect of feeding a purified magnesium-deficient diet by tube to two elderly male subjects. Neither had significant gastrointestinal, renal, endocrine or other disease which might modify magnesium or other nutritional requirements.

In the initial depletion studies, plasma magnesium levels fell slowly but progressively for several months to levels approximately one-third to one-fourth the control levels and then stabilized. Red cell magnesium levels fell more slowly and after three months were two-thirds of normal.

In one subject symptoms and signs occurred after approximately a hundred days of depletion. These included personality changes, symptoms of gastrointestinal disturbance, gross tremor, fasciculations and hyporeflexia in the presence of positive Trousseau and Chvostek signs. These reverted to normal following the administration of magnesium salts and did not recur with continuation of the supplemented diet for another five months. In the second subject signs of paralytic ileus developed after fifty-five days of depletion in the first study, but only electromyographic changes in the second study which lasted for a period of thirty-eight weeks.

Despite an adequate calcium intake, serum calcium levels fell markedly in both subjects as the hypomagnesemia persisted. Hypokalemia developed and large additional intakes of potassium were required for maintenance of serum levels; this was correlated with decreased total exchangeable potassium.

In both subjects, serum calcium levels returned to normal following magnesium repletion, and serum potassium levels rose. In view of the hypocalcemia accompanying hypomagnesemia in these subjects and the dramatic improvement with magnesium repletion, it is suggested that these two ions, as well as potassium, are intimately related in their metabolism. Serial data on serum phosphorus, uric acid, cholesterol and proteins are presented.

When supplemented with magnesium and adequate absorbable iron, the purified diet utilized in this study is capable of maintaining weight and good general health over a prolonged period.