Reference
Kazaks AG, Uriu-Adams JY, Albertson TE, et al. The effect of oral magnesium supplementation on measures of airway resistance and subjective assessment of asthma control and quality of life in men and women with mild to moderate asthma: a randomized placebo controlled trial. J Asthma. 2010;47:83-92.
Design
Randomized, double-blind intervention trial
Participants
55 adults with mild to moderate asthma who used only beta-agonists or inhaled steroids for asthma control
Study Medication and Dosage
170 mg magnesium (Mg) from Mg citrate given b.i.d., or placebo for 6.5 months
Primary Outcome Measures
Methacholine challenge test, a variety of pulmonary function tests, subjective quality of life scores, C-reactive protein (CRP), and exhaled nitric oxide (NO)
Key Findings
Peak expiratory flow rates increased 6% in the Mg group (P=0.03), though several additional parameters of lung function did not change significantly in the Mg group. The concentration of methacholine required to cause a 20% reduction in force expiratory volume increased in the Mg group while slightly declining in the placebo group (P=0.02; specific data not provided). On a 7-point quality of life index, the Mg group experienced a 0.5-point improvement (P=0.004) versus a 0.2-point improvement with placebo (NS). Indicators of inflammation, NO, and CRP levels did not improve significantly in either group.
Practice Implications
While most Americans consume less than recommended amounts of Mg, some but not all, previous research indicates that asthma sufferers tend to have even lower Mg status than do other Americans.1
While most Americans consume less than recommended amounts of Mg, some but not all, previous research indicates that asthma sufferers tend to have even lower Mg status than do other Americans.
Mg is believed to have bronchodilatory and anti-inflammatory effects that might help asthma patients. However, previous Mg trials studying therapeutic effects in asthmatics have produced only mixed results.
The primary factor separating the current trial from previous negative reports is duration. The 6.5-month intervention used by these researchers was significantly longer than the 3- to 12-week interventions employed elsewhere. The authors show that previous trials studying bronchial responsiveness have produced positive results when interventions have lasted several months, but negative results when they only occurred for several weeks. These new findings should change our view of the appropriate length of time needed to evaluate the effects of Mg supplementation in people with asthma.
