The Role of Calcium and Magnesium in Asthma


Calcium is known primarily for its function as the main mineral component of bones. But calcium has other important functions, some of which are pertinent to asthma. The control of smooth muscle contraction is governed by changes in the intracellular concentration of calcium ions. (1) In the presence of calcium, ATPase is activated to hydrolyse ATP and provides an available energy source for muscle contraction.

Bones act as a calcium reservoir, supplying calcium when blood values decline and absorbing excesses when blood values are elevated above normal values. Calcium blood levels are generally independent of dietary intake, but may be altered by regulatory controls such as glandular malfunction or lack of vitamin D. (2)


Mg is a cofactor in over one hundred enzyme reactions in the body and as such is important for protein formation, DNA production and nerve conduction. Magnesium is also important in bone formation. Magnesium is normally conserved by the kidneys and intestinal mechanisms, allowing blood levels to remain stable through a wide range of dietary intakes. Magnesium assists in calcium uptake, but it also competes with dietary calcium for the same absorption site in the intestine. Excessive dietary calcium (or phosphorus) is much more likely to block magnesium absorption than vice- versa in the typical American diet. Magnesium absorption is also inhibited by excessive dietary fat, phosphate, lactose, phytates and oxalates which form insoluble compounds with magnesium. Magnesium is also lost in diarrhea, long term use of diuretics, excessive sugar intake and protein malnutrition. (3-6)

In the intracellular fluid compartment, magnesium is the second most abundant cation, after potassium. (7) The two cations are so strongly associated that that it is difficult to maintain cellular potassium levels during magnesium depletion , despite adequate potassium intake. Thus adequate body stores of magnesium and adequate repletion are necessary to prevent and effectively treat potassium loss. (8,9)


In the last half million years of evolution, the human body developed mechanisms to conserve sodium, a sometimes rare commodity and excrete potassium, the most common mineral in the primitive diet. The main regulator of this mechanism is the adrenal hormone, aldosterone. Potassium salts are excreted in the normal functioning of the kidney but in varying degrees of dehydration even more potassium is lost (in the urine) from the intracellular compartment as the body attempts to save remaining water along with sodium. Modern diets and lifestyles tend toward chronic elimination of potassium and its metabolic partner, magnesium.

When asthmatics are put on intravenous fluid repletion in an emergency room situation, potassium is the first component.


Magnesium is essential in muscle relaxation after contraction. A severe Mg deficiency causes neuromuscular symptoms such as tetany, an extreme and prolonged contraction of the muscles (10) Within the cells of striated and smooth muscles, magnesium is considered a natural calcium antagonist counteracting the adverse effects of excessive intracellular calcium. Excess magnesium blocks calcium entry, while low magnesium levels potentiate the actions of calcium. (11,12) Magnesium also plays a key role in the production of energy which is needed by the chest wall muscles and the diaphragm to perform the work of breathing. In a double blind study, individuals with low magnesium levels had an increase in the power of their respiratory muscles after receiving an intravenous infusion of magnesium. This effect was not seen in healthy individuals with normal magnesium levels. (13)


It is generally thought that magnesium depletion leads to respiratory fatigue. (14). Magnesium promotes healthy lung function by acting as a bronchodilator, preventing the bronchial passages from going into spasm. (15, 16) Magnesium deficiency may increase vulnerabilty to allergies by increasing the release of histamine into the bloodstream, increasing allergic reactivity in general. (17) Magnesium has been found to be deficient in many asthmatics during acute attacks (18), though actual Mg levels may have been lower since blood level measurements do not detect subtle tisssue deficiencies (19). Low dietary intake of magnesium is associated with an increased incidence of asthmatic symptoms, wheezing and reduced lung function. (20)

The administration of intravenous magnesium has been shown to be effective in the treatment of bronchial asthma symptoms. (21, 22)


Many factors in modern life tend to reduce of many nutrients including dietary magnesium and its metabolic partner, potassium. This affects the population in general and asthmatics specifically. First, there are lower levels of minerals in food today due to depletion of the soil in modern farming methods. (23) Modern methods of milling, processing and the preservation of food cause nutrient losses, eg 85% of magnesium is removed from whole wheat in the milling. (24)The typical American diet often fails to provide the provide a minimum level of 350 mg/day of magnesium. (25) Low dietary intake of magnesium is associated with an increased incidence of asthmatic symptoms, wheezing and reduced lung function. (26)

Other factors which drive down magnesium levels in the population include stress, lack of sleep, exposure to noise, mainly through increased urinary excretion. (27-29)

Finally, many medications used in routine asthma treatment have specifically noted diuretic and/or magnesium-reducing side effects. (30)


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2) Whitney EN, Cataldo CB, Rolfes SR, Understanding Normal and Clinical Nutrition, 1991, West Publishing Co., p292)

3) Bunce G, Chiemchaisri Y, Phillips P:The mineral requirements of the dog. IV. Effect of certain dietary and physiologic factors upon magnesium deficiency syndrome. J Nutr 1962; 76:23-29

4) Meyer H, Busse F: Investigations about storage and mobilization of magnesium in bones, in Cantin M. Seelig M (eds): Magnesium in Health and Disease. New York, SP Medical Science Books, 1980 pp337-341

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7) Rhoades and Tanner, op. cit p457

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10) Whitney, Cataldo and Rolfes, op. cit. p301-302

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19) Fiaccadori E, et al. Muscle and serum magnesium in pulmonary intensive care unit patients. Crit Care Med, 1988; 16: 751-760

20) Britton, J, et al. Dietary magnesium, lung function, wheezing and airway hyperreactivity in a random adult population sample. The Lancet, 334, Aug 6, 1994:357-62

21) Haury, VG Blood serum magnesium in bronchial asthma and its treatment by the administration of magnesium sulfate.

22) Skobeloff, EM et al. Intravenous magnesium for the treatment of acute asthma in the emergency department. JAMA 1989; 262: 1210-1213

23) Hall RH. The agribusiness view of soil and life. J Holistic Med 1981; 3:157-166

24) Schroeder, HA. Losses of vitamins and trace minerals resulting from processing and preservation of foods. AM J Clin Nutrition 1971; 24:562-573

25) Morgan KJ et al. Magnesium and calcium dietary intakes of the US population. J Am Coll Nutr 1985; 4: 195-206

26) Britton, J, et al. Dietary magnesium, lung function, wheezing and airway hyperreactivity in a random adult population sample. The Lancet, 334, Aug 6, 1994:357-62

27) Seelig MS and Master MPH, Stress and dyspnea increase the need for Magnesium J AM Coll Nutr 13(5), 429-446 1994

28) Henrette, JG. Type A behaviour and magnesium metabolism. Magnesium, 1986; 5:201-210

29) Rayssiguier, Y. Hypomagnesemia resulting from adrenaline infusion in ewes: its relation to lipolysis. Horm Metab Res, 1977; 9: 309-314

30) Phillips, PJ et al. Metabolic and cardiovascular side effects of the B2 adrenoceptor agonist salbutamol and rimiterol. Br J Clin Pharmacol, 1980; 9:483-491

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