This study enrolled 835 healthy, full-term infants in Santiago, Chile. From 6-12 months infants were fed iron-fortified (mean 12.7mg/L) or low-iron (mean 2.3mg/L) formula milk. At 10 years of age 473 (56.6%) of the children were assessed for IQ, spatial memory, arithmetic achievement, visual-motor integration, visual perception, and motor functioning.
Compared with the low-iron group, the iron fortified group scored lower on every 10 year outcome.
Betsy Lozoff, MD; Marcela Castillo, PhD; Katy M. Clark, MA; Julia B. Smith, EdD. Iron-Fortified vs Low-Iron Infant Formula: Developmental Outcome at 10 Years. Arch Pediatr Adolesc Med. Published online November 7, 2011. doi:10.1001/archpediatrics.2011.197
For more information on the iron content of UK follow-on formula milk see the Caroline Walker Trust report Infant Milks in the UK (2011).
Idjradinata et al, (1994). Adverse effect of iron supplementation on weight gain of iron-replete young children. The Lancet, Volume 343 (8908). May 21, 1994. 1252-1254.
Morley et al, (1999). Iron fortified follow on formula from 9 to 18 months improves iron status but not development or growth: a randomised trial.Arch Dis Child 1999; 81:247-252 doi:10.1136/adc.81.3.247
Moy R (2000). Iron fortification of infant formula. Nutrition Research Reviews, 13, 215-227.