Trace Elements in Human Milk from Italian Lactating Women: Comparison with Infant Formulas

Background: Human milk is the best source of nutrition for the newborns, and exclusive breastfeeding is recommended by WHO up to 6 months of age. It contains all the nutrients and essential trace elements necessary to ensure correct functioning of the organism. Infant formulas, the most common substitutes for human milk, usually contain nutrient levels modeled to have a composition similar to human milk. However, few recent data on nutrient levels in breast milk and infant formula are available from women living in Italy. The aim of this study was to determine the levels of five essential (Fe, Zn, Cu, Mn, Se) and four non-essential/toxic elements (Ni, Cr, Cd, Pb) in infant formulas and breast milk of women living in Modena, Italy and to compare them with recommended values. Methods: 130 samples of human milk (mature milk: 30-40 days postpartum) and a representative sample of infant formulas (0-6 months) sold in Italy were analyzed by ICP-MS in triplicate after microwave digestion. Results: Breast milk showed adequate levels of essential trace elements, despite the inter-individual variability observed, which was not influenced by women' characteristics and dietary habits. Non-essential/toxic elements content was well below the maximum tolerable limits set by the European Food Safety Authority (EFSA). In infant formulas as well, essential element levels were within the European recommended values, however, Fe and Mn levels, were significantly higher than in breast milk. Conclusions: The levels of essential micronutrients in lactating women living in Modena are suitable for the proper development of infants and no risk for excessive toxic elements intake was detected. Infant formulas show high fortification with Fe and Mn. Considering the growing evidence of cognitive development effects due to an excessive Mn intake, a deeper discussion on infants' Mn requirement is needed. According to our findings, breastfeeding should be still encouraged and recommended.