Role of infant early cow's milk formula exposure

It is now well accepted that early introduction of certain potentially allergenic foods as peanut and egg contribute to the reduction of allergy to these foods. Cow's milk is unique among the early introduction foods because it can be readily given from birth as cow's milk formula (CMF). However, the key issue is that this breaches WHO recommendations of 6 months exclusive breastfeeding (EBF). While partial CMF supplementation might not lead to discontinuation of breastfeeding, it does interfere with breastfeeding performance (reduces duration and reduces amount the infant receives). Thus, the key unique issue with cow's milk exposure in early infancy is that it is unethical to randomize between breastfeeding and formula feeding. The result is that most of the literature is observational. In addition, the effect of transient CMF exposure in maternity wards is not always accounted for, and the distinction between IgE- and non-IgE-mediated cow's milk allergy (CMA) is not always made. Moreover, the variability in the amount of CMF exposure in early infancy, from transient top ups on post-natal (maternity) wards, through to infants who are exclusively CMF fed, can critically impact the outcome of CMA. The available data suggests that early introduction of CMF is effective in preventing CMA. While how early remains a question, it is clear that once CMF is introduced, it should be persistently provided, in order to prevent the development of CMA.