Influence of prenatal iron and zinc supplements on supplemental iron absorption, red blood cell iron incorporation, and iron status in pregnant Peruvian women

BACKGROUND: It is estimated that 60% of pregnant women worldwide are anemic. OBJECTIVE: We aimed to examine the influence of iron status on iron absorption during pregnancy by measuring supplemental iron absorption, red blood cell iron incorporation, and iron status in pregnant women. DESIGN: Subjects were 45 pregnant Peruvian women (33+/-1 wk gestation), of whom 28 received daily prenatal supplements containing 60 mg Fe and 250 microg folate without (Fe group, n = 14) or with (Fe+Zn group, n = 14) 15 mg Zn, which were were consumed from week 10 to 24 of gestation until delivery. The remaining 17 women (control) received no prenatal supplementation. Iron status indicators and isotopes were measured in maternal blood collected 2 wk postdosing with oral (57Fe) and intravenous (58Fe) stable iron isotopes. RESULTS: Maternal serum ferritin and folate concentrations were significantly influenced by supplementation (P < 0.05). Serum iron was also significantly higher in the Fe than in the Fe+Zn (P < 0.03) or control (P < 0.001) groups. However, the supplemented groups had significantly lower serum zinc concentrations than the control group (8.4+/-2.3 and 10.9+/-1.8 micromol/L, respectively, P < 0.01). Although percentage iron absorption was inversely related to maternal serum ferritin concentrations (P = 0.036), this effect was limited and percentage iron absorption did not differ significantly between groups. CONCLUSIONS: Because absorption of nonheme iron was not substantially greater in pregnant women with depleted iron reserves, prenatal iron supplementation is important for meeting iron requirements during pregnancy.     

Maternal iron status influences iron transfer to the fetus during the third trimester of pregnancy

BACKGROUND: The effect of maternal iron status on fetal iron deposition is uncertain. OBJECTIVE: We used a unique stable-isotope technique to assess iron transfer to the fetus in relation to maternal iron status. DESIGN: The study group comprised 41 Peruvian women. Of these women, 26 received daily prenatal supplements containing iron and folate (n = 11; Fe group) or iron, folate, and zinc (n = 15; Fe+Zn group) from week 10-24 of pregnancy to 1 mo postpartum. The remaining 15 women (control group) received iron supplementation only during the final month of pregnancy. During the third trimester of pregnancy (+/- SD: 32.9 +/- 1.4 wk gestation) oral 57Fe (10 mg) and intravenous 58Fe (0.6 mg) stable iron isotopes were administered to the women, and isotope enrichment and iron-status indicators were measured in cord blood at delivery. RESULTS: The net amount of 57Fe in the neonates' circulation (from maternal oral dosing) was significantly related to maternal iron absorption (P < 0.005) and inversely related to maternal iron status during the third trimester of pregnancy: serum ferritin (P < 0.0001), serum folate (P < 0.005), and serum transferrin receptors (P < 0.02). Significantly more 57Fe was transferred to the neonates in non-iron-supplemented women: 0.112 +/- 0.031 compared with 0.078 +/- 0.042 mg in the control group (n = 15) and the Fe and Fe+Zn groups (n = 24), respectively (P < 0.01). In contrast, 58Fe tracer in the neonates' circulation was not significantly related to maternal iron status. CONCLUSION: The transfer of dietary iron to the fetus is regulated in response to maternal iron status at the level of the gut.     

Maternal zinc supplementation does not affect size at birth or pregnancy duration in Peru.

To estimate the effect of maternal zinc deficiency on pregnancy outcomes, we conducted a zinc supplementation trial in an urban shantytown in Lima, Peru, a population with habitual low zinc intakes. Beginning at 10-24 wk gestation, 1295 mothers were randomly assigned to receive prenatal supplements containing 60 mg iron and 250 (g folate, with or without 15 mg zinc. Women were followed up monthly during pregnancy. At birth, newborn weight was recorded, and crownheel length, head circumference and other circumferences and skinfold thicknesses were assessed on d 1. At delivery, 1016 remained in the study; duration of pregnancy was known for all women, and birth weight information was available for 957 newborns. No differences were noted in duration of pregnancy (39.4 +/- 2.2 vs. 39. 5 +/- 2.0 wk) or birth weight (3267 +/- 461 vs. 3300 +/- 498 g) by prenatal supplement type (iron + folate + zinc vs. iron + folate; P > 0.05), and there were no differences in the rates of preterm (<37 wk) or post-term (>42 wk) delivery, low birth weight (<2500 g) or high birth weight (>4000 g). Finally, there were no differences by prenatal supplement type in newborn head circumference, crownheel length, chest circumference, mid-upper arm circumference, calf circumference or skinfold thickness at any of three sites. Adjustment for covariates and confounding factors did not alter these results. Adding zinc to prenatal iron and folate tablets did not affect duration of pregnancy or size at birth in this population.     

Trial of zinc supplements in relation to pregnancy outcomes, hematologic indicators, and T cell counts among HIV-1-infected women in Tanzania

BACKGROUND: In observational studies, the zinc status of HIV-infected persons has been associated with both positive and adverse clinical outcomes. Such endpoints may affect the risk of adverse birth outcomes among HIV-infected women. OBJECTIVE: We examined the effects of zinc supplements on birth outcomes, hematologic indicators, and counts of T lymphocyte subsets among 400 HIV-infected pregnant women. DESIGN: Eligible women between 12 and 27 wk of gestation were randomly assigned to daily oral supplementation with either 25 mg Zn or placebo between recruitment and 6 wk after delivery. All women received iron, folic acid, and multivitamin supplements irrespective of the experimental assignment. RESULTS: We observed no significant differences in birth weight, duration of gestation, or fetal and neonatal mortality between women in the zinc and placebo groups. Hemoglobin concentrations increased between baseline and 6 wk postpartum in both groups. However, the rise in hemoglobin over this period was significantly lower (P = 0.03) in the zinc group (x +/- SD: 11.5 +/- 17.9 g/L) than in the placebo group (15.2 +/- 18.6 g/L). Similarly, the changes in red blood cell count and in packed cell volume over the same period were significantly lower in the zinc group (P < 0.01 and P = 0.01, respectively). Zinc had no effect on CD4(+), CD8(+), or CD3(+) cell counts during the follow-up period. CONCLUSION: Because of the lack of beneficial effects of zinc on adverse pregnancy outcomes and the likelihood of negative effects on hemoglobin concentrations, no compelling evidence exists to support the addition of zinc to prenatal supplements intended for pregnant HIV-infected women.     

Adding zinc to prenatal iron and folate supplements improves maternal and neonatal zinc status in a Peruvian population.

BACKGROUND: Maternal zinc deficiency during pregnancy may be widespread among women in developing countries, but few data are available on whether prenatal zinc supplementation improves maternal and neonatal zinc status. OBJECTIVE: We studied whether maternal zinc supplementation improved the zinc status of mothers and neonates participating in a supplementation trial in a shantytown in Lima, Peru. DESIGN: Beginning at gestation week 10-24, 1295 mothers were randomly assigned to receive prenatal supplements containing 60 mg Fe and 250 microg folate, with or without 15 mg Zn. Venous blood and urine samples were collected at enrollment, at gestation week 28-30, and at gestation week 37-38. At birth, a sample of cord vein blood was collected. We measured serum zinc concentrations in 538 women, urinary zinc concentrations in 521 women, and cord zinc concentrations in 252 neonates. RESULTS: At 28-30 and 37-38 wk, mothers receiving zinc supplements had higher serum zinc concentrations than mothers who did not receive zinc (8.8 +/- 1.9 compared with 8.4 +/- 1.5 micromol/L and 8.6 +/- 1.5 compared with 8.3 +/- 1.4 micromol/L, respectively). Urinary zinc concentrations were also higher in mothers who received supplemental zinc (P < 0.05). After adjustment for covariates and confounding factors, neonates of mothers receiving zinc supplements had higher cord zinc concentrations than neonates of mothers who did not receive zinc (12.7 +/- 2.3 compared with 12.1 +/- 2.1 micromol/L). Despite supplementation, maternal and neonatal zinc concentrations remained lower than values reported for well-nourished populations. CONCLUSION: Adding zinc to prenatal iron and folate tablets improved maternal and neonatal zinc status, but higher doses of zinc are likely needed to further improve maternal and neonatal zinc status in this population.     

Maternal zinc supplementation and growth in Peruvian infants

BACKGROUND: Little is known about how maternal zinc intake influences growth in utero and in postnatal life in humans. OBJECTIVE: We aimed to assess the effect of maternal zinc supplementation during pregnancy on infant growth through age 1 y. DESIGN: A double-blind, randomized controlled trial of prenatal zinc supplementation was conducted from 1995 to 1997 in Lima, Peru. Women (n = 1295) were enrolled at 15.6 +/- 4.6 wk gestation and assigned to receive daily supplements with zinc (15 mg Zn + 60 mg Fe + 250 microg folic acid) or without zinc (60 Fe + 250 microg folic acid) through pregnancy to 1 mo after delivery. At birth, 546 infants were followed for 12 mo to assess growth. Anthropometric measures of body size and composition were collected monthly, and morbidity and dietary intake surveillance was carried out weekly. RESULTS: No differences in maternal socioeconomic characteristics by treatment group or follow-up period were found. Infants born to mothers prenatally supplemented with zinc had significantly (P < 0.05) larger average growth measures beginning in month 4 and continuing through month 12. In longitudinal regression modeling, prenatal zinc was associated with greater weight (by 0.58 +/- 0.12 kg; P < 0.001), calf circumference (by 1.01 +/- 0.21 cm; P < 0.001), chest circumference (by 0.60 +/- 0.20 cm; P = 0.002), and calf muscle area (by 35.78 +/- 14.75 mm(2); P = 0.01) after adjustment for a range of covariates. No effect was observed for linear growth. CONCLUSION: Maternal zinc supplementation in this population was associated with offspring growth, which is suggestive of lean tissue mass accretion.     

Changes in iron status during pregnancy in peruvian women receiving prenatal iron and folic acid supplements with or without zinc

BACKGROUND: Iron deficiency anemia is the most prevalent nutrient deficiency during pregnancy, yet there are few data on the effect of prenatal iron supplementation in women in developing countries. OBJECTIVE: Our objective was to describe the effect of iron supplementation on hematologic changes during pregnancy, and the effect on those changes of adding zinc to the supplements. DESIGN: Pregnant women were enrolled in a randomized, double-masked study conducted at a hospital in a shantytown in Lima, Peru. Women were supplemented daily from 10-24 wk gestation to 4 wk postpartum with 60 mg Fe and 250 microg folic acid with or without 15 mg Zn. Hemoglobin and ferritin concentrations were measured in 645 and 613 women, respectively, at enrollment, at 28-30 and 37-38 wk gestation, and in the cord blood of 545 neonates. RESULTS: No differences in iron status were detected by supplement type, but hematologic changes were related to initial hemoglobin status. Women with anemia (hemoglobin <110 g/L) showed steady increases in hemoglobin concentration throughout pregnancy whereas women with relatively higher initial hemoglobin concentrations had declining values during mid pregnancy, then rising values by 37-38 wk gestation. Women with an initial hemoglobin concentration >95 g/L showed increases in serum ferritin by the end of the pregnancy. Despite supplementation, women with poorer hematologic status; who were younger, single, and multiparous; and who consumed fewer supplements were more likely to have anemia at the end of pregnancy. CONCLUSIONS: These hematologic changes are congruent with the effects of iron supplementation reported in placebo-controlled trials and the addition of zinc did not significantly affect them.     

Multivitamin-mineral supplementation is not as efficacious as is iron supplementation in improving hemoglobin concentrations in nonpregnant anemic women living in Mexico

BACKGROUND: Iron supplements improve hemoglobin status and reduce anemia due to iron deficiency. It is not known whether multiple micronutrient (MM) supplements are as efficacious as are iron supplements alone in improving hemoglobin concentrations. OBJECTIVE: We conducted a randomized, double-blind community trial in Mexico to compare the efficacy of MM supplements containing iron with that of iron alone in improving hemoglobin concentrations in nonpregnant women. DESIGN: Nonpregnant women (n = 158) were recruited from a semirural community in Mexico and were randomly assigned to receive iron alone (60 mg; Fe group) or MM supplements (vitamins A, B complex, C, D, E, and K and iron, zinc, and magnesium; MM group) 6 d/wk in their home for 12 wk. Hemoglobin concentrations were measured in capillary blood samples at baseline and follow-up. RESULTS: The treatment groups (MM: n = 75; Fe: n = 77) did not differ significantly at recruitment in age, schooling, literacy, or socioeconomic status. There were no significant differences between groups in compliance (median: 97.5%), baseline hemoglobin concentrations, or prevalence of anemia (20%). Losses to follow-up (4%) and mean (+/-SD) changes in hemoglobin (MM group: 6.7 +/- 10.6 g/L; Fe group: 7.1 +/- 13.6 g/L) were not significantly different between groups. However, the change in hemoglobin in anemic subjects was greater in the Fe group than in the MM group (P < 0.05 for interaction), and there was no significant difference in nonanemic subjects. CONCLUSIONS: MM supplements may not be as efficacious as is iron alone in improving the hemoglobin status of anemic women.     

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. DESIGN: 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.     

Iron supplements inhibit zinc but not copper absorption in vivo in ileostomy subjects

BACKGROUND: Iron supplements may inhibit intestinal zinc and copper uptake because these elements may compete for binding to a transporter molecule (divalent metal transporter 1) that is located on the apical side of the small intestinal epithelium. OBJECTIVE: We quantified the interaction between different amounts of administered iron and the absorption of zinc and copper in humans. DESIGN: Eleven subjects with an ileostomy [mean (+/- SD) age: 55 +/- 9 y] ingested a stable-isotope-labeled zinc and copper solution containing 12 mg Zn ((66)Zn and (67)Zn) and 3 mg Cu ((65)Cu) in the presence of 0, 100, or 400 mg Fe as ferrous gluconate on 3 respective test days. Subsequently, 1 mg (70)Zn was injected intravenously. Subjects collected ileostomy effluent and urine for 24 h and 7 d, respectively. Zinc status and true zinc absorption were calculated from the urinary excretion of the zinc isotopes. Apparent copper absorption was calculated from ileostomy effluent excretion of the orally administered copper isotopes. RESULTS: Zinc status did not differ significantly between the 3 iron doses. Mean (+/- SEM) zinc absorption was significantly higher in the absence of iron than with the concomitant ingestion of 100 or 400 mg Fe (44 +/- 22% compared with 26 +/- 14% and 23 +/- 6%, respectively; P < 0.05), whereas zinc absorption did not differ significantly between the 100- and 400-mg Fe doses. Apparent copper absorption was 48 +/- 14%, 54 +/- 26%, and 53 +/- 7% in the presence of 0, 100, and 400 mg Fe, respectively, and did not differ significantly between the 3 iron doses. CONCLUSION: Oral iron therapy may impair zinc absorption and thus zinc status in a dose-independent fashion but does not affect copper absorption.     

Utilization of iron from an animal-based iron source is greater than that of ferrous sulfate in pregnant and nonpregnant women

Heme iron absorption during pregnancy and the role of hepcidin in regulating dietary heme iron absorption remains largely unexplored. The objective of this research was to examine relative differences in heme (animal based) and nonheme (ferrous sulfate) iron utilization. This study was undertaken in 18 pregnant (ages 16-32 y; wk 32-35 of gestation) and 11 nonpregnant women (ages 18-27 y). Women were randomly assigned to receive both an animal-based heme meal (intrinsically labeled (58)Fe pork) and labeled ferrous sulfate ((57)Fe) fed on alternate days. Blood samples obtained 2 wk postdosing were used to assess iron status indicators and serum hepcidin and iron utilization based on RBC incorporation of iron isotopes. Heme iron utilization was significantly greater than nonheme iron utilization in the pregnant (47.7 ± 14.4 vs. 40.4 ± 13.2%) and nonpregnant women (50.1 ± 14.8 vs. 15.3 ± 9.7%). Among pregnant women, utilization of nonheme iron was associated with iron status, as assessed by the serum transferrin receptor concentration (P = 0.003; r(2) = 0.43). In contrast, heme iron utilization was not influenced by maternal iron status. In the group as a whole, women with undetectable serum hepcidin had greater nonheme iron utilization compared with women with detectable serum hepcidin (P = 0.02; n = 29); however, there were no significant differences in heme iron utilization. Our study suggests that iron utilization from an animal-based food provides a highly bioavailable source of dietary iron for pregnant and nonpregnant women that is not as sensitive to hepcidin concentrations or iron stores compared with ferrous sulfate.     

Inorganic zinc and the intestinal absorption of ferrous iron

The effect of inorganic zinc on the absorption of inorganic iron (Fe+2) from a solution was assessed in two studies on healthy male volunteers. In the first study coadministration of 344 mumol of zinc had no effect (p less than 0.5) on the absorption of 842 mumol of radiolabeled Fe, assessed by the area under plasma Fe increment time curve during the 3 (AUC3) and 6 (AUC6) h postadministration (Fe alone AUC3 = 176.4 +/- 39.3; AUC6 = 387 +/- 101; Fe + Zn AUC3 = 180 +/- 33.1; AUC6 = 396 +/- 73.1 mumol.h-1.L-1), total plasma content of 59Fe, and whole-body retention of 59Fe. In the second study only the plasma appearance of Fe was monitored. After administration of 421 mumol of Fe alone, the AUC3 and AUC6 were 167 +/- 21.2 and 429.4 +/- 57 mumol.h-1.L-1, respectively; these were reduced to 56.4 +/- 17 and 119 +/- 34 (p less than 0.002) by 421 mumol Zn and further reduced by 1048 mumol Zn to 33 +/- 15 and 43.4 +/- 23.8 mumol.h-1.L-1 (p less than 0.001), respectively. It is concluded that Zn can impair the intestinal absorption of Fe.     

Supplemental zinc lowers measures of iron status in young women with low iron reserves

Zinc and iron compete during intestinal absorption, but postabsorptive interactions between these nutrients are less clear. Understanding these interactions is important to determine when supplementation with iron or zinc is proposed. The effect of zinc supplementation (22 mg Zn/d as zinc gluconate) or of iron supplementation (100 mg Fe/d as ferrous sulfate) for 6 wk on iron and zinc metabolism and absorption was evaluated in young women with low iron reserves. Young adult women (ages 20-28 y), nonanemic but with low iron stores (plasma ferritin< 20 microg/L), participated in the 70-d study. The women were divided in two groups (zinc-supplemented, n = 11; iron-supplemented, n = 12). The supplements were taken at bedtime. Iron and zinc biochemical indices and intestinal absorption were measured on d 1 and 56. Radioiron and stable isotopes of zinc were used to measure iron and zinc absorption from a test meal. In the iron-supplemented group, blood hemoglobin, plasma ferritin and the percentage of transferrin saturation increased (P < 0.01). Zinc indices did not change. In the zinc-supplemented group, plasma ferritin and the percentage of transferrin saturation decreased (P < 0.05), whereas the plasma transferrin receptor and erythrocyte zinc protoprophyrin levels increased (P < 0.05). Plasma and urinary zinc also increased (P < 0.01). Iron absorption (%) from the test meal increased (P < 0.01), whereas zinc absorption (%) decreased (P < 0.01) compared with baseline in the Zn-supplemented women. Our results indicate that the use of iron supplements in women with marginal iron status improves iron indices with no effect on zinc status. However, use of a modest zinc supplement improves zinc indices, but also appears to induce a cellular iron deficiency and, possibly, further reduce iron status.     

Multiple micronutrient supplementation during pregnancy does not lead to greater infant birth size than does iron-only supplementation: a randomized controlled trial in a semirural community in Mexico

BACKGROUND: Little is known about the benefits of prenatal multivitamin and mineral supplements in reducing low birth weight. OBJECTIVE: We conducted a randomized, double-blind clinical trial in semirural Mexico to compare the effects of multiple micronutrient (MM) supplements with those of iron supplements during pregnancy on birth size. DESIGN: Pregnant women (n = 873) were recruited before 13 wk of gestation and received supplements 6 d/wk at home, as well as routine antenatal care, until delivery. Both supplements contained 60 mg Fe, but the MM group also received 1-1.5 times the recommended dietary allowances of several micronutrients. RESULTS: At recruitment, the women in the 2 groups were not significantly different in age, parity, economic status, height, or hemoglobin concentration but differed significantly in marital status (4.6% and 2.0% of women in the MM and iron-only groups, respectively, were single mothers) and mean (+/- SD) body mass index (in kg/m(2); 24.6 +/- 4.3 and 23.8 +/- 3.9 in the iron-only and MM groups, respectively). Losses to follow-up (25%) and compliance (95%) did not differ significantly between the groups. In intent-to-treat analyses (MM group: n = 323; iron-only group: n = 322), mean (+/- SD) birth weight (2.981 +/- 0.391 and 2.977 +/- 0.393 kg in the MM and iron-only groups, respectively) and birth length (48.61 +/- 1.82 and 48.66 +/- 1.83 cm in the MM and iron-only groups, respectively) did not differ significantly between the groups. CONCLUSION: These findings suggest that MM supplementation during pregnancy does not lead to greater infant birth size than does iron-only supplementation.     

Maternal iron and zinc supplementation during pregnancy affects body weight and iron status in rat pups at weaning

Pregnant women worldwide are frequently iron (Fe) and zinc (Zn) deficient. Therefore, cosupplementation with Fe and Zn during pregnancy is common. Although Fe supplementation programs are successful, studies suggest that Zn supplementation negatively affects maternal Fe metabolism. However, little is known about the effects of maternal Fe or Zn supplementation on Fe metabolism in the offspring. We developed a rat model to investigate if Fe and/or Zn supplementation during pregnancy affects regulation of nonheme Fe absorption and Fe status in offspring and if these effects are dependent upon maternal Fe and Zn status at conception. Control (C; fed a Fe- and Zn-adequate diet; 75 and 25 μg/g, respectively) or Fe- and Zn-deficient (D; fed a Fe- and Zn-deficient diet; 12 and 10 μg/g, respectively) rats were supplemented with Fe (27 mg/wk), Zn (4.5 mg/wk), Fe+Zn (27 mg Fe, 4.5 mg Zn/wk), or placebo throughout pregnancy. At postnatal d 21, body weight (BW), hemoglobin (Hb), hematocrit (Hct), liver and intestine Fe concentration, liver hepcidin, and intestine Fe transporter expression were determined in pups. Zn supplementation of C dams decreased pup BW (P < 0.0001), whereas it increased pup BW in D dams (P < 0.0001). Zn supplementation of C dams did not affect Hb and Hct in pups but increased the liver Fe concentration (P = 0.0002). However, Zn supplementation of D dams decreased hepcidin expression in their offspring (P < 0.0001). In C dams, Fe and Fe+Zn supplementation decreased ferroportin levels in pup intestine compared with pups from unsupplemented dams (P < 0.05). In conclusion, Zn supplementation of dams with adequate Fe and Zn status increases offspring liver Fe concentration and postnatally compromises BW. Therefore, potential adverse effects of Zn supplementation should be evaluated.     

A single 60-mg iron dose decreases zinc absorption in lactating women

This study determined whether a single 60-mg dose of ferrous sulfate interferes with fractional zinc absorption (FZA) at 7-9 wk of lactation. In a crossover design, 5 exclusively breast-feeding women were given either a single 60-mg iron supplement or no supplement. FZA was measured by analyzing zinc stable isotope tracers ((70)Zn and (67)Zn) in urine samples collected for 7 d after isotope dosing. A 0.7-micromol intravenous (IV) infusion of (70)Zn as ZnCl(2) in saline was followed by a 0.03-mmol oral dose of (67)Zn as ZnCl(2) given with a standardized meal. After a 7-d wash-out period, the supplement given was reversed and a second FZA measurement was taken. FZA was calculated from isotopic enrichments in urine measured by inductively coupled plasma mass spectrometry. Hemoglobin, plasma ferritin and transferrin receptor, and plasma 5'-nucleotidase, plasma zinc and erythrocyte zinc did not differ before the two measurements of zinc absorption. When women were given a single iron supplement, FZA was significantly lower, 21.7 +/- 1.7% compared with 26.9 +/- 2.6% when no supplement was given (P = 0.032). A single 60-mg iron dose significantly decreases FZA during early lactation.     

孕期补充钙、铁、锌对胎儿生长发育的影响

目的以孕妇为对象,研究孕中期单纯补钙和补钙同时补铁和/或锌对婴儿生长发育的影响.方法选择初产健康孕妇313名,分别强化维生素D(VD)、钙、铁和锌, 从孕5月至分娩时止.分娩时测量胎盘重量、胎盘和脐带血中微量元素的含量、新生儿的出生体重和身长.结果对照组胎盘重量最大,钙和多种微量元素的含量较低,而钙+铁+锌+VD组相反,并且对照组的胎盘重量(551.1±64.2) g显著大于钙 +铁+锌+VD组(467.1±36.6) g.脐血中血红蛋白含量显著高于母血,碱性磷酸酶活性差异无显著性,脐血血浆中钙、铁、锌含量均高于母血.婴儿的生长发育结果显示,钙+铁+ 锌 +VD组新生儿的出生体重(3.53±0.33) kg和身长值最大,并且出生体重显著大于对照组的(3.28±0.54) kg.结论孕期联合补充钙、铁、锌, 使其达到或接近每日膳食中营养素供给量,这是改善婴儿生长发育的最佳方式.     

A community-based randomized controlled trial of iron and zinc supplementation in Indonesian infants: interactions between iron and zinc

BACKGROUND: Combined supplementation with iron and zinc during infancy may be effective in preventing deficiencies of these micronutrients, but knowledge of their potential interactions when given together is insufficient. OBJECTIVE: The goal was to compare the effect in infants of combined supplementation with iron and zinc and of supplementation with single micronutrients on iron and zinc status. DESIGN: Indonesian infants (n = 680) were randomly assigned to daily supplementation with 10 mg Fe (Fe group), 10 mg Zn (Zn group), 10 mg Fe + 10 mg Zn (Fe+Zn group), or placebo from 6 to 12 mo of age. Venous blood samples were collected at the start and end of the study. Five hundred forty-nine infants completed the supplementation and had both baseline and follow-up blood samples available for analysis. RESULTS: Baseline prevalences of anemia, iron deficiency anemia (anemia and low serum ferritin), and low serum zinc (< 10.7 micromol/L) were 41%, 8%, and 78%, respectively. After supplementation, the Fe group had higher hemoglobin (119.4 compared with 115.3 g/L; P < 0.05) and serum ferritin (46.5 compared with 32.3 microg/L; P < 0.05) values than did the Fe+Zn group, indicating an effect of zinc on iron absorption. The Zn group had higher serum zinc (11.58 compared with 9.06 micromol/L; P < 0.05) than did the placebo group. There was a dose effect on serum ferritin in the Fe and Fe+Zn groups, but at different levels. There was a significant dose effect on serum zinc in the Zn group, whereas no dose effect was found in the Fe+Zn group beyond 7 mg Zn/d. CONCLUSION: Supplementation with iron and zinc was less efficacious than were single supplements in improving iron and zinc status, with evidence of an interaction between iron and zinc when the combined supplement was given.     

Supplementation with zinc between meals has no effect on subsequent iron absorption or on iron status of Chilean women

OBJECTIVE: Studies on the effect of zinc (Zn) supplementation on iron absorption and iron status have shown mixed results. We investigated the effect of daily supplementation with 20 mg of Zn for a period of 2 mo on iron absorption and iron status of Chilean women. METHODS: Forty-four non-anemic, clinically healthy women 35 to 45 y of age were randomly selected to receive daily 20 mg of Zn, as Zn sulfate, or a placebo between meals for a period of 2 mo. Iron and zinc biochemical indicators and iron absorption studies were assessed at baseline and at the end of the study. Iron absorption was measured using the double radioisotopic technique. RESULTS: The geometric mean (range +/- 1 standard deviation) absorption of iron before supplementation between the Zn-supplemented and placebo groups was similar (31.2, 11.2 +/- 86.3, versus 27.4, 14.4 +/- 52.2, respectively, P = 0.97). Absorption increased significantly after the 2-mo supplementation period (P = 0.049), but there were no group-wise differences at the end of the trial (34.4, 17.5 +/- 67.3, versus 39.8, 20.9 +/- 75.8, respectively, P = 0.97). The geometric mean plasma Zn concentrations did not change significantly in either group during the course of the study (P = 0.47). There was no significant effect of Zn supplementation on any of the iron indicators studied. CONCLUSION: Supplementation of 20 mg of Zn between meals for a period of 2 mo had no effect on subsequent iron absorption or iron status of Chilean women.     

Serum zinc changes due to iron supplementation in teen-age pregnancy

Serum zinc and iron concentrations in a group of pregnant teen-agers supplemented with a multivitamin were compared during pregnancy with a group supplemented with a multivitamin containing 18 mg Fe. Serum measurements were at 13 wk of gestational age (prestudy) and during supplementation at 20, 32, and 38 wk, delivery, and 4 and 12 wk postpartum. Hematocrit measurements were used to adjust the measured metal concentrations for the diluting effect of the normal blood-volume increase. The non-Fe-group mean, adjusted serum Zn concentrations showed no change, but the serum Fe decreased to 28% below prestudy concentrations at 38 wk. In contrast, the Fe-supplementation group showed a progressive increase in Fe concentrations to a maximum of 38% above prestudy concentrations at 4 wk postpartum and a 35% decrease from prestudy Zn concentrations during the third trimester. The results of this study suggest that 18 mg Fe/d is adequate supplementation for nonanemic teen-age pregnancy and depresses the serum Zn concentration.