Magnesium can have effects that counter the two main problems asthmatics face: broncho-constriction and inflammation. Magnesium is a natural bronchodilator, which means that it expands the bronchial tubes allowing increased airflow to and from the lungs.
It also has anti-inflammatory effects which reduce the inflammation common in chronic asthma sufferers without steroids or the possible side-effects of NSAIDs.
A study from Argentina found that magnesium offered intravenously to young severe asthma patients during the first hour of their hospitalization reduced the number of children who needed mechanical ventilation support.
A recent study from the Institute of Environmental Medicine found Magnesium intake seems to have a protective effect on childhood asthma by protecting against oxidative tissue damage (Clin Exp Allergy. 2012 Oct;42(10):1491-500.) , while an earlier study published in the Journal of Emergency Medicine found that using magnesium in combination with standard asthma medication can prove beneficial to children with mild to moderate asthma.
Anecdotes from asthma sufferers indicate that with careful avoidance of asthma triggers, diet modifications, and supplementation with magnesium and other foods and herbs known to help asthmatics like fenugreek, butterbur, vitamin C and D, licorice root and others have freed them from their reliance on asthma medications.
While magnesium isn’t a cure-all for asthma, there is evidence that taking a magnesium supplement could be helpful as a preventative measure against acute attacks, and to supplement a prescribed bronchodilation drug. Using magnesium and other herbal and plant-based remedies known to ease the symptoms of asthma may help mild asthmatics reduce their need for inhalers and pharmaceuticals, especially in the seasons when the effects of the disease are the worst.