Trace element absorption in infants as a foundation to setting upper limits for trace elements in infant formulas.

Area of Science:

• Nutritional Science
• Pediatric Nutrition
• Biochemistry

Background:

• Human milk provides high bioavailability of essential trace elements like iron, zinc, copper, and manganese.
• Cow's milk and infant formulas often have lower trace element bioavailability.
• Factors influencing trace element absorption include milk composition and interactions between elements.

Purpose of the Study:

• To compare trace element bioavailability across different milk sources.
• To identify factors affecting trace element absorption in infants.
• To propose upper limits for trace elements in infant formulas.

Main Methods:

• Comparative analysis of trace element bioavailability.
• Literature review on factors influencing absorption (e.g., lactoferrin, phytate, casein, ascorbate, citrate).
• Assessment of trace element interactions and competition for absorption pathways.

Main Results:

• Human milk shows higher bioavailability of iron, zinc, copper, and manganese compared to cow's milk and formulas.
• Lactoferrin, ascorbate, and citrate enhance trace element uptake.
• Casein and phytate can inhibit absorption; imbalances in trace element ratios (Fe/Zn, Zn/Cu, Fe/Mn) impair absorption.

Conclusions:

• Human milk's composition promotes optimal trace element absorption.
• Infant formula development should consider factors that enhance or inhibit absorption.
• Suggested upper limits for iron (14 mg/l), zinc (12 mg/l), copper (1.2 mg/l), and manganese (0.6 mg/l) in formulas.
• Further research is needed on infant adaptation to varying trace element intakes.