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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #113758
Title: PRENATAL IRON SUPPLEMENTS IMPAIR ZINC ABSORPTION IN PREGNANT PERUVIAN WOMEN

Author
item O'BRIEN, KIMBERLY - JOHNS HOPKINS
item ZAVALETA, NELLY - INSTITUTO DE INVESTIGACIO
item CAULFIELD, LAURA - JOHNS HOPKINS
item WEN, JIANPING - BCM
item Abrams, Steven

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2000
Publication Date: 9/1/2000
Citation: N/A

Interpretive Summary: Iron deficiency is thought to be the most widespread nutritional deficiency in the world. Women have greater iron demands than men, and have increased risk of iron deficiency. It has been estimated that nearly half of nonpregnant women, and 60 percent of pregnant women, are anemic. Iron deficiency anemia during pregnancy can adversely affect a woman's health and increase the risk of her baby being born prematurely. We wanted to examine the influence of iron status on iron absorption during pregnancy by using stable isotopes to measure supplemental iron absorption, red blood cell iron incorporation, and iron status in pregnant women. Our subjects were pregnant Peruvian women in a community with a high prevalence of iron deficiency anemia. Some of the women were given daily prenatal iron supplements; some were given iron plus zinc; others were given no supplements. We also wanted to determine any potential interactions from giving both nutrients at the same time. Iron supplementation had a positiv effect on iron status, although zinc levels in the blood were lower than in women who did not consume supplements. Ultimately, the results showed that prenatal iron supplementation is important for meeting iron requirements during pregnancy. Further work must be done to determine the optimal mineral composition of prenatal supplements.

Technical Abstract: Prenatal iron supplements may adversely influence zinc absorption during pregnancy. To examine the impact of prenatal iron supplements on supplemental zinc absorption, fractional zinc absorption was measured in 47 pregnant Peruvian women during the third trimester of pregnancy (33 +/- 1 wk gestation). Of these 47 women, 30 received daily prenatal supplements for wk 10-24 of pregnancy until delivery. Supplements contained 60 mg of Fe and 250 ug of folate without iron group (Fe), n=16) or with iron and zinc supplemented group (Fe + Zn), n=14) 15 mg of Zn. The remaining 17 women [unsupplemented control group (C)] received no prenatal supplementation. Zinc concentrations were measured in plasma, urine, and cord blood and percentage zinc absorption was determined following dosing with oral (**67Zn) and intravenous (**70Zn) stable zinc isotopes. Percentage zinc absorption was significantly lower than controls in fasting gwomen receiving iron-containing prenatal supplements (20.5 +/- 6.4 vs. 20. +/- 4.6 vs 47.0 +/- 12.6%, Fe, Fe + Zn and C groups respectively, P < 0.0001, n=40). Plasma zinc concentrations were also significantly lower in the Fe group compared to the C group (8.2 +/- 2.2 vs 9.2 +/- 2.2 vs. 10.9 +/- 1.8 umol/L, Fe, Fe + Zn and C groups respectively, P = 0.002) and cord zinc concentrations were significantly related to maternal plasma Zn levels (y = 6.383 + 0.555x, r = 0.486, P = 0.002). The inclusion of zinc in prenatal supplements may reduce the potential for iron supplements to adversely influence zinc status in populations at risk for deficiency in both these nutrients.