Table 1.

Evidence table: study description and characteristics

S. no	Setting	Study type	Age/gender	Duration	Intervention group		Control group	Outcomes
					Sample size, exposure and dose	Intervention and dose	Sample size, control and dose
1. Bede et al.46	Outpatient setting, Hungary	Randomized, double-blind, placebo-controlled trial	Children aged 4–16 years. 24 boys and 16 girls (17 M/7F) in the intervention group (11 M/5F) in the placebo group	4-weeks run-in period. 12-week treatment period.	24 children received the intervention	16 children, children < 7 years old received 200 mg, and children > 7 years old received 290 mg Mg-citrate daily	16 children received 260 mg glucose placebo tablets	Changes in FEV1, bronchodilators dose and daytime symptoms scores were recorded on a personal diary card.
2. Bede et al.44	Outpatient setting, Hungary	Randomized, double‐blind, placebo‐controlled trial	Aged 4–16 years. 62 boys and 27 girls. (40 M/14F) in the intervention group, and (22 M/13F) in the placebo group	4-week run-in period, 12-week treatment period	54 patients received the intervention.	Children < 7 years old received 200 mg, and children > 7 years old received 290 mg Mg-citrate daily	35 patients received 260 mg glucose as a placebo	The number of bronchodilator doses and daytime activity and symptoms, night-time awakenings, scores were recorded each day on a personal diary card, measurement of FEV1 at each visit was chosen to follow up progression
3. Fogarty et al.32	24 primary care practices, Nottingham UK	Randomized, placebo-controlled, double-blind parallel-group trial	Aged 18–60 years. 112 males and 205 females (33 M/66F) in the Mg intervention group (42 M/64F) in the placebo group	3-week run-in period, 16-week treatment period	99 patients	Magnesium amino-chelate 450 mg/day (27.6 mmol) plus vitamin C placebo	106 patients double-matched placebo	Primary outcome measure was change between weeks 0 and 16 in a single summary statistic, which combined categorical changes in all of the below measures, with equal weight given to each outcome (−1 for worse, 0 for same and +1 for better asthma control) Secondary outcomes: FEV1, FVC, average morning and evening peak flow, average daily bronchodilator use and daily symptom score recorded in a diary for the preceding 2 weeks. (Inhaled dose of methacholine causing a 20% fall in FEV1 (PD20). to a maximum dose of 12.25 mmol methacholine)
4. Fogarty et al.35	24 primary care practices, Nottingham UK	Randomized, placebo-controlled, double-blind parallel-group trial	Aged 18–60 years. 40 males and 52 females (8 M/31F) in the Mg intervention group (18 M/14F) in the placebo group	10 weeks	31 patients	Magnesium amino-chelate 450 mg/day (27.6 mmol) plus vitamin C placebo	32 patients double-matched placebo	Decrease in individual inhaled corticosteroid dose achieved in each active supplement group relative to placebo
5. Kazaks et al.36	Outpatient setting, USA	Randomized, placebo-controlled, double-blind parallel-group trial	16 males and 36 females, (7M/18F) in the intervention group (9M/18F) in the placebo group	6.5 months	28 patients	340 Mg-citrate daily	27 patients placebo. (two patients were lost to follow up)	Primary outcome: change in bronchial responsiveness as measured by a positive methacholine challenge test in which methacholine provoked a 20% decrease in FEV1 from baseline Secondary outcomes: changes in subjective measures of asthma control, pulmonary function tests, indices of bronchial and systemic inflammation, and Mg status
6. Gontijo-Amaral et al.34	Outpatient setting, division of pulmonology, allergy and immunology, Brazil	A double-blind randomized parallel placebo-controlled study	Aged 7–19 years. 19 males and 18 females (12 M/6F) received the intervention (7 M/12F), received the placebo	2 months	18 patients	300 mg magnesium-glycine daily	19 patients received glycine as placebo	Primary outcome: bronchial reactivity evaluated with methacholine challenge test (PC20) Secondary outcome: asthma symptoms, lung function and allergen-induced skin responses
7. Fathi et al.47	Outpatient setting, Allergy & pulmonology department, Iran	Double-blind, placebo-controlled clinical trial	Asthmatics 19–55 years of age. 53 males and 47 females (25 M/25F) received the intervention, (28 M/22F) the placebo	2 months	50 patients	340 mg of Mg-citrate	50 patients Matched placebo	FEV1, FVC and FEV1/FVC ratio
8. Petrov et al.45	Outpatient setting, MOH, Russia	Open-labeled comparative randomized parallel-group study	Asthmatic children, aged 6–18 years. 36 males and 14 females (17 M/8F) received the intervention, (19 M/6F) were in the control group	24 weeks	25 patients	Magnesium B6 forte (Sanofi-Aventis, France) orally at a dose of 20 mg/kg/day (maximum dose of 2000 mg/day), they received tablets 1 month prior to the study?	25 patients No placebo is given	Daytime symptoms, night-time symptoms, bronchodilator use and number of asymptomatic days