Geographical, seasonal and formula-specific variations in the selenium levels of infant formulae

Fortification of infant formulae with selenium (Se) is currently under consideration by manufacturers and regulatory bodies. However, information on the endogenous Se levels of infant formulae is largely lacking. The objective of this study was to describe the seasonal-, geographic- and formula-specific variations in endogenous Se levels of infant formulae.For most milk-based infant formulae and follow-on formulae, endogenous Se levels were from 4 to 10 μg/l and 5 to 14 μg/l, respectively. Higher Se levels were found for milk-based formulae from the USA (10–15 μg/l) and India (11–22 g/l). The lowest endogenous Se levels (2.5–4 μg/l) were observed for soy-based formulae. No differences were found between whey-adapted, casein-predominant or protein-hydrolysate formulae.The protein source was the major determinant (>95%) of the endogenous formula Se content. The seasonal variations observed in the Se contents of formulae were due to corresponding variations in Se contents of the protein sources.The present study indicated that the endogenous Se level of infant formulae is generally lower than that reported for human milk, and provides information that will need to be considered concerning the need for, and the level of, Se fortification.