Isotopic and trace element evidence of dietary transitions in early life.

CONTEXT: Nursing behaviour has significant implications for individual health and population dynamics. Reconstruction of infant and early childhood diet has become a key focus in studies of past populations.
OBJECTIVE: This paper reviews knowledge about how trace element and stable isotope composition of bone and dental tissues changes during development and how this may influence interpretation of biology and behaviour in past populations.
METHODS: Studies of recent populations and osteological samples were reviewed.
RESULTS: Four distinct stages of nutritional intake are recognized: gestation, exclusive breastfeeding, a transitional or weaning stage and fully weaned. The trace element and stable isotope composition of developing foetal and infant tissues differs during each of these stages due to differences in the source of nutrients and changes in metabolic parameters.
CONCLUSION: Interpretation of early lifetime diet from trace element or stable isotope values requires a comprehensive and validated physiological model for changes during and at the transition between dietary stages. Micro-sampling of dental tissues offers the potential to reconstruct an individual record of early lifetime diet within a chronological framework and has several advantages over traditional cross-sectional techniques. Further research is necessary to understand the factors influencing intra-tooth variability in recovered signals and their chronological interpretation.