Oral magnesium supplementation in children with cystic fibrosis improves clinical and functional variables: a double-blind, randomized, placebo-controlled crossover trial.

Double-blind, randomized, placebo-controlled crossover trial conducted at a single center in Brazil. The active magnesium arm included 22 children and adolescents with cystic fibrosis; all 22 were analyzed and there were no dropouts.

Oral magnesium-glycine (magnesium amino acid chelate) was given at 300 mg/day once daily for 8 weeks, with a 4-week washout between crossover periods. The active regimen was compared with placebo in a double-blind trial.

Oral magnesium supplementation improved respiratory muscle strength and clinical status in pediatric cystic fibrosis, with no adverse effects reported. In the magnesium arm, urinary magnesium increased from 39.69 6 9.46 to 76.08 6 16.09 mg/d, SK score improved from 80.05 6 10.65 to 84.52 6 9.62, and both MIP and MEP increased by about 11% to 12% predicted. The improvements in MIP, MEP, and SK score were all significant (P < 0.001).

The trial was small, single-center, and limited to pediatric cystic fibrosis patients, which restricts generalizability. Each treatment period was short, so durability of benefit and longer-term safety were not established. The crossover design also limits inference beyond the studied conditions and time frame.