Comparison of complementary feeding strategies to meet zinc requirements of older breastfed infants.
BACKGROUND
The low zinc intake from human milk at ∼6 mo of age predicts the dependence on complementary foods (CF) to meet the zinc requirements of older breastfed-only infants.


OBJECTIVE
The objective of this study was to compare major variables of zinc homeostasis and zinc status in 9-mo-old breastfed infants who were randomly assigned to different complementary food regimens.


METHODS
Forty-five exclusively breastfed 5-mo-old infants were randomly assigned to receive commercially available pureed meats, iron-and-zinc-fortified infant cereal (IZFC), or whole-grain, iron-only-fortified infant cereal (IFC) as the first and primary CF until completion of zinc metabolic studies between 9 and 10 mo of age. A zinc stable-isotope methodology was used to measure the fractional absorption of zinc (FAZ) in human milk and CF by dual-isotope ratios in urine. Calculated variables included the dietary intake from duplicate diets and 4-d test weighing, the total absorbed zinc (TAZ) from FAZ × diet zinc, and the exchangeable zinc pool size (EZP) from isotope enrichment in urine.


RESULTS
Mean daily zinc intakes were significantly greater for the meat and IZFC groups than for the IFC group (P < 0.001); only intakes in meat and IZFC groups met estimated average requirements. Mean (±SEM) TAZ amounts were 0.80 ± 0.08, 0.71 ± 0.09, and 0.52 ± 0.05 mg/d for the meat, IZFC, and IFC groups, respectively (P = 0.027). Zinc from human milk contributed <25% of TAZ for all groups. The EZP correlated with both zinc intake (r = 0.43, P < 0.01) and TAZ (r = 0.54, P < 0.001).


CONCLUSIONS
Zinc requirements for older breastfed-only infants are unlikely to be met without the regular consumption of either meats or zinc-fortified foods.
Department of Pediatrics, Section of Nutrition, School of Medicine, University of Colorado Denver, Aurora, CO 80045, USA. nancy.krebs@ucdenver.edu
Nancy F
NF
Krebs
Jamie E
JE
Westcott
Diana L
DL
Culbertson
Lei
L
Sian
Leland V
LV
Miller
K Michael
KM
Hambidge
D015415:Biomarkers / Q000097:blood / Q000652:urine; D001942:Breast Feeding; D003120:Colorado; D002523:Edible Grain / Q000737:chemistry; D005260:Female; D005527:Food, Fortified / Q000032:analysis; D006706:Homeostasis; D006801:Humans; D007223:Infant; D007225:Infant Food / Q000032:analysis*; D007227:Infant Nutritional Physiological Phenomena; D007408:Intestinal Absorption; D008297:Male; D008461:Meat Products / Q000032:analysis; D008895:Milk, Human / Q000737:chemistry; D009751:Nutritional Requirements; D009752:Nutritional Status; D010833:Phytic Acid / Q000008:administration & dosage / Q000032:analysis; D015032:Zinc / Q000008:administration & dosage* / Q000032:analysis / Q000172:deficiency / Q000378:metabolism
D015415:Biomarkers; D010833:Phytic Acid; D015032:Zinc