Zinc homeostasis in Malawian children consuming a high-phytate, maize-based diet.
BACKGROUND
Zinc deficiency in children is an important public health concern in the developing world, and the consumption of predominantly cereal-based diets with a high phytate content may contribute to the risk. The gastrointestinal tract plays a central role in absorbing and conserving zinc, yet it has not been carefully studied in such children.


OBJECTIVE
This study investigated zinc homeostasis in healthy, free-living Malawian children with habitually high-phytate diets to better understand the role of the gastrointestinal tract.


METHODS
We evaluated zinc homeostasis in 10 children aged 2-5 y who were consuming a maize-based diet (phytate:zinc molar ratio of 23:1). Zinc stable isotopes were administered orally and intravenously. The tracer and tracee were measured in urine and feces.


RESULTS
Endogenous fecal zinc was high in comparison with results for this measure in previous studies. Typical correlations seen in subjects consuming a low-phytate diet between total absorbed zinc, the size of the exchangeable zinc pool, and endogenous fecal zinc were not observed. Fractional absorption of zinc was 0.24.


CONCLUSIONS
Zinc homeostasis was perturbed, particularly by large, endogenous fecal zinc losses, in this vulnerable population. The effects of interventions to improve zinc status, including dietary phytate reduction, on zinc homeostasis merit further study.
Manary
Mark J
MJ
Department of Pediatrics, Washington University School of Medicine, St Louis, USA. manary@kids.wustl.edu
Hotz
Christine
C
Krebs
Nancy F
NF
Gibson
Rosalind S
RS
Westcott
Jamie E
JE
Broadhead
Robin L
RL
Hambidge
K Michael
KM
D001682:Biological Availability; D002664:Child Nutritional Physiological Phenomena; D002675:Child, Preschool; D005243:Feces / Q000737:chemistry; D005260:Female; D005504:Food Analysis; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D007408:Intestinal Absorption; D008295:Malawi; D008297:Male; D010833:Phytic Acid / Q000008:administration & dosage / Q000009:adverse effects* / Q000378:metabolism; D013054:Spectrophotometry, Atomic; D011795:Surveys and Questionnaires; D016482:Urinalysis; D003313:Zea mays / Q000009:adverse effects; D015032:Zinc / Q000008:administration & dosage / Q000172:deficiency / Q000378:metabolism* / Q000493:pharmacokinetics; D015033:Zinc Isotopes
D015033:Zinc Isotopes; D010833:Phytic Acid; D015032:Zinc