Investigation of the effect of short-term change in dietary magnesium intake in asthma.

The European respiratory journal
Q1
Oct 1997
Citations:82
Influential Citations:4
Interventional (Human) Studies
82
High RoB
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Methods
Design: randomized, cross-over, double-blind, placebo-controlled. Participants: Twenty nonsmoking asthmatic adults aged 25-60 years; complete data available for 17 (10 male, 7 female; mean age 44.8). Most used inhaled corticosteroids (n=16); two used sodium cromoglycate; one used an oral methylxanthine.
Intervention
Oral magnesium amino acid chelate tablets delivering 400 mg elemental magnesium daily (two 200 mg tablets) for 3 weeks in each of two treatment periods.
Results
Magnesium did not significantly improve objective outcomes: FEV1 difference 0.072 L (95% CI −0.083 to 0.227; p=0.29); PD20,FEV1 difference 0.30 log10 (95% CI −0.02 to 0.63; p=0.09); amplitude of mean PEF difference 0.012 (95% CI −0.15 to 0.17; p=0.79). However, asthma symptom scores declined with magnesium (median −3.8 points per 7 days; p=0.02), and bronchodilator use trended lower (median −6.0 doses per 7 days; p=0.051). Serum magnesium increased with magnesium intake (end 0.86 mM vs 0.80 mM; p=0.025); 24 h urinary magnesium excretion rose (end 5.61 vs 3.88 mmol; p=0.004); leucocyte magnesium did not change (p=0.86). Conclusion: short-term higher magnesium intake may improve symptomatic control in stable asthma but does not clearly improve lung function or airway reactivity; the study was underpowered, and longer trials are needed to determine clinical value.
Limitations
Small sample size (n=17 completed); underpowered to detect modest changes in objective outcomes (estimated 88 participants needed to detect the observed 72 mL FEV1 difference); short treatment periods (3 weeks) may be insufficient to alter total body magnesium stores; subjects had mild, stable asthma (mean FEV1 ~78% predicted), limiting generalizability; concomitant asthma medications and dietary magnesium variations could confound results; some PD20 measurements were censored.

Abstract

Epidemiological evidence suggests that a low dietary intake of magnesium is associated with impaired lung function, bronchial hyperreactivity and wheezing. This study was designed to investigate whether short-term alterations of dietary magnesium int...