Abstract
Despite intensive research in infant nutrition throughout this century, uncertainty persists over nearly every major aspect of practice. Reasons for this uncertainty are analysed and the need for prospective studies on the later effects of early diet is justified. Evidence is presented that nutrition at a critical or sensitive period in early life predetermines future metabolism, performance and morbidity in animal models. Similar data in Man have been collected mainly in retrospective and flawed studies and are correspondingly less convincing. A prospective multicentre randomized study on preterm infant feeding is discussed to illustrate the feasibility of conducting long-term outcome studies in Man and to emphasize the critical importance of outcome data as a basis for clinical practice. Preliminary evidence from this study suggests that the way a preterm infant is fed, in just the early weeks post partum, may have a major impact on later growth and development.