The effect of different energy densities of complementary foods on breast milk consumption is not well understood. In this study, we tested the hypothesis that provision of fortified spread (FS), a micronutrient fortified, energy-dense (22 kJ/g), ready-to-use food, to Malawian infants would not decrease their breast milk intake more than a traditional corn + soy blended flour (CSB). Forty-four healthy 6-mo-old infant and mother pairs were enrolled in a prospective, parallel group, investigator-blinded, randomized controlled complementary feeding trial. Infants were randomized to receive 25 g/d of FS, 50 g/d of FS, or 72 g/d of CSB. The primary outcome was the difference in breast milk intake after 1 mo of complementary feeding as measured by the dose-to-mother deuterium oxide dilution technique. Outcomes were compared using repeated measures ANOVA. A total of 41 mother-infant pairs completed the study. At enrollment, 88% of the infants had received corn porridge. At baseline, the infants consumed 129 +/- 18 g.kg body wt(-1) x d(-1) (mean +/- SD) of breast milk. After 1 mo of complementary feeding with 25 g/d FS, 50 g/d FS, or 72 g/d CSB, their breast milk consumption was 115 +/- 18 g.kg body wt(-1) x d(-1), a significant reduction; however, the effects of the complementary foods did not differ from one another (F-value model = 4.33, P = 0.0008 for effect of time and P = 0.69 for effect of type of food). The results suggest that complementary feeding of Malawian infants with FS has the same effect on their breast milk intake as complementary feeding with traditional CSB porridge.