Complementary feeding represents the transition period from breastfeeding to the family dietary habits. Human milk usually meets the infants’ dietary needs up to 6 months, but an even earlier introduction (providing the 4th month of life is completed) can be considered on an individual basis.

Most available data seem to indicate that the maintenance of breastfeeding to the 6–12-month period may have independent effects in preventing obesity and overweight through the paediatric age and promoting neurodevelopmental performance later on. Also the introduction of gluten in the 4–7-month period while the infant is still breastfed seems to be connected with a minor risk not just of overt coeliac disease, but also type 1 diabetes. Preliminary trials of long-chain polyunsaturated fatty acid supplementations through the complementary feeding period have produced good results on neurofunctional tests in the short term, but we need more data on the long-term assessments. The same considerations apply to earlier meat introduction in complementary feeding, particularly in breastfed babies, for neurodevelopmental advantages. It is not clear whether the effect should be ascribed to a specific nutrient or to food as a whole. The traditional preventive effect of the later introduction of solids on the allergy risk does not show convincing evidence, nevertheless, care should be taken to match the family expectations in terms of dietary prescriptions. This is the challenge of complementary feeding today, that is, meeting family traditional beliefs and habits while considering the most recent scientific evidence.