The timing of the introduction of complementary foods appears crucial to the development of allergic diseases later in life. The results from recent observational studies might be misinterpreted to suggest that introducing complementary food prior to the age of four months might have a beneficial effect on the induction of immune tolerance. Since these two recently published papers cannot completely account for reverse causation, as is the case for all observational studies, we recommend that the current ESPGHAN and American Academy of Pediatrics recommendations be maintained as long as new evidence from large randomized controlled intervention trials do not suggest otherwise. That is, complementary foods should be first introduced between the age of 17 to 26 weeks.
Keywords: allergy; food diversity; infancy; prevention; solid food.