A previous randomized trial on the subject of complementary feeding during infancy focused on infants from a low-resource country that were exclusively breastfed over a period of six months showed lower iron stores compared to breastfeeding infants receiving solid foods. The trial was a step in the right direction, but randomized trials of exclusive breastfeeding in high-income countries has been lacking.
A study in this month’s issue of Pediatrics attempted to tackle this issue, focusing on infants who receive complementary foods in a high-income country in addition to breast milk from four months of age. These infants had higher iron stores at six months compared with those exclusively breastfed for six months.
The study’s authors hypothesized that iron status would be better in infants who received complimentary foods in addition to breastfeeding as opposed to those exclusively breastfed.
One hundred and nineteen healthy term singleton infants were randomly assigned either complimentary nutrition or exclusive breastfeeding for six months for the trial. The authors found that, of the infants who completed the trial, those in the complementary foods trial had higher mean serum ferritin levels at six months, while no difference was found between the groups in iron deficiency anemia, iron deficiency, or iron depletion. Additionally, infants in both groups grew at the same pace.
The results show that even in a high-income country, adding small amounts of complementary foods in addition to breastfeeding an infant from four months of age doesn’t affect the growth rate between 4 and 6-months, but it does have a small and positive effect on iron status at six months. The authors admit:
“In this study, conducted in an urban setting in a high-income country, the biological signiﬁcance of the higher SF levels among those infants who began complementary feeding at 4 months of age remains to be determined.”