Clinically, calcium, iron and zinc deficiencies are mostly seen in children, and it is generally recommended that they are best taken about half an hour after a meal. Children are prone to nutritional imbalances and calcium-iron-zinc deficiencies, especially calcium, during their growth and development. Calcium deficiency can cause infants and children to suffer from occipital baldness, night crying, thinning hair, sweating, night terrors and other symptoms, and in severe cases, rickets may occur. Iron deficiency mainly leads to anemia, and zinc deficiency may cause heterophagia, mental retardation, etc. These micronutrient deficiencies require timely supplementation and are generally recommended to be taken after meals. As children’s digestive system is not well developed, taking them before meals may cause nausea and vomiting, resulting in reduced absorption. This can be avoided by taking it after a meal, and the pH of the stomach is more appropriate, which also helps to dissociate calcium and promote its absorption. Calcium, iron and zinc should be tested under the guidance of a doctor before deciding whether or not to take the medication, and it is also best to take the three elements separately.