Professor Dell medical School The University of Texas at Austin Dell Medical School Austin, Texas, United States
Background: The application of absorption factors to iron intake data from the Feeding Infants and Toddlers Study (FITS) dietary recall data demonstrated a high level of inadequate intakes. Similar to iron, zinc (Zn) is essential and older breastfed infants rely on complementary foods for adequate intakes.
Objective: To use the FITS 2016 dietary intake data and accepted absorption factors to calculate the mean estimated absorbed daily Zn intake, rank the dietary sources of Zn, and assess the percentage of breastfed, mixed fed, and formula fed infants at risk for inadequate Zn intakes.
Design/Methods: FITS is a large, nationwide, cross-sectional survey exploring food and nutrient intakes of young children under age 4 in the US. This analysis was focused on 6-11.9 month old infants (n=902). The percentage of breastfed (n=296), mixed fed (n=102), and formula fed (n=448) infants with Zn intakes below the Estimated Average Requirement (EAR = 2.5mg) were determined. Then, absorption factors of 50% for breastmilk and 30% for all other dietary sources were applied to Zn intake. Mean absorbed Zn intakes and the percentage of infants falling below the absorbed dietary Zn requirement utilized to establish the EAR were calculated. Unpaired t-tests were used to assess differences in mean Zn intakes and percentage of infants below the daily absorbed Zn requirement between groups.
Results: Among 6-8.9 month old infants, 73% of breastfed (n=153), 6% of mixed fed (n=71), and 0% of formula fed (n=234) infants had Zn intakes below the EAR. When absorption factors were applied, the percentage of infants at risk for inadequate Zn intakes increased to 90.9% of breastfed, 14.5% of mixed fed, and 0.1% of formula fed infants. Among 9-11.9 month old infants, 13% of breastfed (n=143), 7% of mixed fed (n=31), and 0% of formula fed (n=214) infants had Zn intakes below the EAR. When absorption factors were applied, 33.4% of breastfed, 13.8% of mixed fed, and 0.0% of formula fed infants had calculated absorbed Zn intakes below the daily absorbed Zn requirement. Sources of zinc are shown in Table 1. Conclusion(s): When established factors to account for bioavailability of dietary Zn sources are applied, a substantial proportion of breastfed older infants are at risk for inadequate Zn intake, especially during the initial time of introduction of solid foods. Focusing on high Zn containing intake, including meat and fortified cereals may be important to assure adequate Zn intake .
