Discussion
internalising and externalising behaviour, micronutrient-enriched milk–cereal mixes
The current study was conducted to measure the effect of supplementing infants, for a period of 180 d, with micronutrient-enriched milk–cereal mixes containing varying amounts of protein (modest and high) on their neurodevelopment at 12 and 24 months of age. We found that compared with no supplementation, those receiving modest amount of protein had better motor scores (about 0·17 Existing direct evidence on the effect of protein supplementation during infancy and early childhood on neurodevelopment is limited and makes it difficult to arrive at a consensus. In most of the available studies, there is a lack of clear specification of the source of animal protein being investigated (i.e. milk or meat based)There are many plausible explanations for why we did not observe significant effects of protein supplementation on neurodevelopment. One of the reasons might be the similarity in the amounts of total protein intake and protein energy ratio between the children in the three study groups. Seemingly adequate protein intake in the control group may be responsible for lack of any additional benefit of moderate or high protein intake. The data from the 24-h dietary recall in a small subsample of children may appear to support this argument. However, there are limitations in terms of extrapolation of the findings of this recall to the entire sample of children studied. We found some positive effect of modest protein supplementation, compared with no-supplement group, on motor scores and infant temperament. This small overall effect might be due to a beneficial effect in subgroups consisting of few participants who would have benefitted from additional protein. Our intervention was focused during second half of infancy, whereas most of the studies that have shown an impact have also covered the period of pregnancy and lactationSimilar to the present study, a recent systematic review and individual participant data meta-analysis (including data from about 30 000 children from thirteen RCT) found a modest improvement in motor, language and socio-emotional scores in children, aged 6–24 months, receiving small quantity lipid-based supplementAnother possible disadvantage of providing infants with high-protein supplements is the likely increase in the risk of adverse metabolic health, as documented in studies from large cohortsThe strength of our study lies in it being a randomised controlled trial done in a community setting. The study achieved high compliance to the supplementation, and the data collection was done by a highly trained team. The neurodevelopment assessments were done in a large sample of infants and children by a team of experienced psychologists. Some limitations included the lack of blinding for the three study groups. However, blinding was ensured for the two supplementation groups by differential coded labelling known only to an independent statistician. At 24 months of age, the behavioural outcomes assessed using CBCL were intended to be presented as proportions, that is, those with internalising and externalising behaviour across the three study groups. However, the numbers of children with clinically significant behavioural problems were very small for a meaningful analysis based on proportions. Another limitation might be in the way we collected data on compliance to milk–cereal mix supplement, that is, by checking empty sachets of the supplement. Empty sachets may not mean that the milk–cereal mix was consumed by the infant enrolled in our study. In the absence of a direct and reliable method of reporting consumption such as directly observed feeding, it may be challenging to ascertain differences in protein intake and utilisation between the groups. We did attempt to minimise sharing by informing the families that the mix was meant only for young children and by providing biscuits/cookies for other children in the household. In about 30 % of the families included in the study, the studied child was of first birth order. This might have reduced the proportion of families in which sharing occurred. However, in spite of these measures, there still remains a possibility of sharing. An additional limitation is that we conducted 24-h dietary recall in a small proportion of infants and children (about 10 % of the total sample) due to limited resources. It may have enhanced our understanding of the findings obtained if a larger subsample of children were assessed for their dietary intakes. Caution should be exercised while drawing interpretations based on data from such a small sample.