The development of food allergy depends on several factors, including genetic factors and early exposure to allergenic proteins in the diet, food protein uptake and handling, and the development of tolerance. Many hypotheses, as regards the possible causal relationships, have been raised during the past few years, including the hygiene theory, the role of bacterial gut flora, and the potential effect of different cytokines in breast milk. Although interesting, these are mainly speculations based on non-interventional and often retrospective/cross-sectional studies including small study populations. These theories remain to be documented in proper, controlled and prospective studies. Breastfeeding and the late introduction of solid foods (>4 months) is associated with a reduced risk of food allergy, atopic dermatitis, and recurrent wheezing and asthma in early childhood. In all infants, breastfeeding should be encouraged for 4-6 months. In high-risk infants a documented extensively hydrolysed formula is recommended if exclusive breastfeeding is not possible for the first 4 months of life. There is no evidence for preventive dietary intervention neither during pregnancy nor lactation. Preventive dietary restrictions after the age of 4-6 months are not scientifically documented.
aDepartment of Pediatrics, Sønderborg Hospital, Sønderborg, Denmark; and bDepartment of Pediatrics, Odense University Hospital, Odense, Denmark
Correspondence to Susanne Halken, MD, Department of Pediatrics, Sønderborg Hospital, DK-6400 Sønderborg, Denmark. Tel: +45 74182765; fax: +45 74182952; e-mail: email@example.com