Zinc absorption by infants

Zinc is a vital mineral in human nutrition and rare cases of overt zinc deficiency are well described in term and preterm infants. A variety of methods have been developed to assess zinc absorption, retention and balance in humans, either using mass (metabolic) balance or stable isotope-based

The different methods have different benefits and disadvantageous. Many studies have used such methods to examine zinc absorption in term and preterm infants. In preterm infants the main interest has been establishing whether different diets lead to positive zinc balance and approached in utero accretion rates. The earliest studies were concerning as they suggested that preterm infants may be in negative zinc balances for prolonged periods after birth. Subsequent studies have been more contradictory and it remains unclear from the literature how much zinc preterm infants absorb early in life. Nor is it clear whether poor zinc absorption during this period has any long-term consequences. Studies in term infants have suggested no such prolonged period of negative zinc balance. Generally the absorption values are in line with those used by the Institute of Medicine in the most recent edition of the Dietary Reference Intakes. Other studies have been designed to assess the effect of changes in formula composition on zinc intake (e.g. the presence or absence of lactose, high vs low zinc contents, etc.). Ho-wever, despite almost 20 studies of zinc absorption in infants many physiologically important questions remain unanswered, especially in preterm infants.