The investigators plan to perform a randomized, mutual-control and double-blinded cohort study to further exploit the vitamin A supplementation on iron metabolic homeostasis (including iron reserve, mobilization and absorption status in the same population) compared with solely iron and vitamin A plus iron.

Inclusion Criteria:

• apparent health;
• Hb concentration>60 g/L;
• C-reaction protein (CRP)<10 mg/L;
• parental or guardian approval of participation in all aspects of the study; and
• parental/guardian agreement to avoid the additional use of vitamin and mineral supplements during the investigation.

Exclusion Criteria:

• does not match the inclusion criteria