The recommended daily allowance (RDA) depends on gender, age, and whether you are pregnant or lactating:^[1][2]

These values correspond to the RDA for total iron, which encompasses both dietary iron (iron assimilated from iron-rich foods) and iron supplements. The need for supplementation depends on the amount of iron absorbed from one's diet. It’s important to avoid exceeding the RDA to prevent excessive iron intake.^[1]

Notably, for infants up to 6 months of age, these values specifically refer to adequate intake (AI), because there is insufficient evidence to establish an RDA for this age group.^[1] The Institute of Medicine (IOM) determined the daily AI by multiplying the average iron content in human milk (0.35 mg/L) by the average milk intake of exclusively breastfed infants (0.78 L/day), resulting in an AI of 0.27 mg/day of iron. These values don’t account for potential variations in the iron concentration of human milk.^[3]

For preterm breastfed infants, a daily oral iron dosage of approximately 2 mg/kg is estimated to be appropriate for preventing iron deficiency (ID) or iron deficiency anemia (IDA) in preterm breastfed babies. Term breastfed infants typically do not require additional iron until around 4 months, at which point supplementation with 1 mg/kg of iron may or may not be required depending on the infant's health status. Formula-fed preterm and term infants may require different dosages if iron supplementation is needed.^[2]

It is worth noting that iron is most effective when administered on an empty stomach or 2 hours after a meal. However, if iron supplements are poorly tolerated due to gastrointestinal side effects, a dose reduction or administration after a meal may be more suitable.^[4]