Effect of zinc supplementation on Physical growth and psychomotor function of school children

INTERVENTION: case:20 mg zinc supplementation daily for 6 months control: 20 mg placebo Intervention 1: control: 20 mg placebo. Intervention 2: case:20 mg zinc supplementation daily for 6 months. Placebo Treatment ‐ Drugs CONDITION: Condition 1: Effect of zinc supplementation on Physical growth. Condition 2: Effect of zinc supplementation on psychomotor function. ; Other lack of expected normal physiological development ; Disturbance of activity and attention Disturbance of activity and attention Other lack of expected normal physiological development PRIMARY OUTCOME: Physical growth. Timepoint: befor, 3 months after, 6 months after. Method of measurement: Balance ,centimeter. Psychomotor function. Timepoint: befor, 3 months after, 6 months after. Method of measurement: Time On Target. INCLUSION CRITERIA: Inclusion: School children, 7‐12 years old, healthy children, agree mentioned parents. Exclusion criteria: Prematurity or low birth weight, chronic disease (marasmus, cystic fibrosis,…), reject of drug by child