Aim: To evaluate the efficacy of iron supplements given at intervals corresponding to the mean life of red blood cells compared to weekly supplementation, in reducing the prevalence of preschool anemia.

Method: Ninety-nine children from public day care centers with ages from 24 to 59 months old were randomly divided into two groups. All the children received 40 doses of 30 mg of ferrous sulfate during a 10-month intervention period. Group 1 received once weekly supplementation and Group 2 received supplementation in two 5-month cycles, each cycle consisting of one month of supplementation (20 workdays) and four months without supplementation.

The prevalence of anemia after the supplementation regimens reduced from 20.20% to 5.05% (P < 0.0005); the reduction was not significantly different between the two groups (P = 0.35). The mean hemoglobin concentration increased in both groups (Group 1: 0.27 g/dL; P < 0.016 and Group 2: 0.47 g/dL; P < 0.0005) without significant differences between the groups (P = 0.17).

Inclusion Criteria:

• The participants of the study were children with ages ranging from 24 to 59 months old that attended four local public day care centers

Exclusion Criteria:

• Presence of infection or reported infections within two weeks prior to the intervention
• Anemia lower than 7.0 g/dL and children taking medications containing ferrous sulfate