The Millennium Cohort Study has prospectively followed a large cohort of babies (n=15,980) to assess whether the timing of the introduction of solids was related to the risk of hospitalisation for diarrhoea and lower respiratory tract infection (LRTI). It has previously been reported that for both diarrhoea and LRTI, the monthly risk of hospitalisation was significantly lower in those receiving breast milk compared with those receiving infant formula. It has been suggested that early introduction of solids increases the vulnerability of the gut to infection, and that the risk of infection is increased by the potential use of contaminated foods or equipment. In addition, it is thought that the high permeability of the immature gut may permit large foreign proteins to penetrate and provoke immune sensitization. However evidence from developed countries is scarce. In this study, infants were followed up monthly to assess whether they had received solids during that month. The mean age for the introduction of solids was 3.8 months with breastfed babies on average starting one week later than formula fed babies. The monthly risk of hospitalisation was not significantly higher in those who had received solids compared with those not on solids and the risk did not vary significantly according to the age of starting solids. The authors comment that the study only followed babies until 8 months of age and therefore was unable to detect any effects of early or delayed weaning later in childhood. The study did not look at other implications of early introduction of solids.
