Table 3:

Effect of iron supplementation on primary outcomes among children aged 5–12 years

Outcome	No. of trials	No. of participants	Effect size (95% CI)	p for effect	I², %
Cognitive performance
Global cognitive performance^*	9	2355	0.50 (0.11 to 0.90)	0.01	93
Intelligence quotient^†	5	1874	5.47 (−3.24 to 14.18)	0.2	97
Growth
Height^†	5	1111	−0.37 (−1.14 to 0.40)	0.3	0
Z score for height^†	5	1318	0.09 (0.01 to 0.17)	0.03	10
Weight^†	5	1111	0.12 (−0.50 to 0.75)	0.7	0
Z score for weight^†	5	1318	0.10 (−0.03 to 0.23)	0.1	70
Hematology and iron indices
Hemoglobin, g/L^†	28	6545	8.38 (6.21 to 10.56)	< 0.001	97
Anemia^‡	7	1763	0.50 (0.39 to 0.64)	< 0.001	85
Iron deficiency^‡	4	1020	0.21 (0.07 to 0.63)	0.006	85
Ferritin, g/L^†	14	3612	28.45 (18.03 to 38.86)	< 0.001	98
Other micronutrients
Serum zinc, mol/L ^†	5	1553	0.16 (−0.46 to 0.79)	0.6	76
Safety
Malaria prevalence^‡	4	919	1.10 (0.94 to 1.29)	0.2	0
Rates of positive malaria test (any species)^§	4	1818	1.05 (0.90 to 1.21)	0.6	0
Gastrointestinal upset^‡	4	576	1.30 (0.89 to 1.91)	0.2	0
Constipation^‡	2	202	3.44 (0.66 to 19.68)	0.2	6
Vomiting^‡	2	202	0.86 (0.13 to 5.67)	0.9	0