Effect of high-dose iron supplements on fractional zinc absorption and status in pregnant women.
BACKGROUND
Women have an increased risk of iron deficiency during pregnancy because of the demands of the developing fetus. Iron supplements are commonly advocated as a prophylactic treatment and are generally taken with meals to reduce side effects, but iron can interfere with the absorption of zinc.


OBJECTIVE
The aim was to determine the effect of consuming an iron supplement (100 mg Fe/d as ferrous gluconate) with meals from 16 wk gestation to term on zinc status and absorption.


METHODS
Stable-isotope techniques were used to measure zinc status (exchangeable zinc pool, EZP) and fractional zinc absorption (FZA) in early and late pregnancy from a meal consumed at a different time from that of iron supplement or placebo consumption in 6 women given iron supplements and 7 given a placebo.


RESULTS
FZA increased during pregnancy, independent of iron supplementation. FZA was significantly higher (P < 0.001) at week 34 than at weeks 16 and 24, and urinary zinc excretion was higher at week 34 than at week 16 (P = 0.02). The size of the EZP remained unchanged throughout pregnancy and was unaffected by iron supplementation. The iron status of iron-supplemented women was higher than that of the placebo group.


CONCLUSIONS
In iron-replete pregnant women who consumed a Western diet, no detectable adverse effects on zinc metabolism were observed after ingestion of 100 mg Fe/d. An increase in the efficiency of zinc absorption was observed during late pregnancy.
Harvey
Linda J
LJ
Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom.
Dainty
Jack R
JR
Hollands
Wendy J
WJ
Bull
Victoria J
VJ
Hoogewerff
Jurian A
JA
Foxall
Robert J
RJ
McAnena
Liadhan
L
Strain
J J
JJ
Fairweather-Tait
Susan J
SJ
D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D019266:Iron, Dietary / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D009752:Nutritional Status; D011247:Pregnancy / Q000378:metabolism*; D011295:Prenatal Care; D016037:Single-Blind Method; D015032:Zinc / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine
D019266:Iron, Dietary; D015032:Zinc