Iron absorption is more closely related to iron status than to daily iron intake in 12- to 48-mo-old children

Few studies have evaluated iron absorption in small children after the first year of life. Our objectives were to examine the relations among iron intake, iron absorption, and iron status in a group of healthy children. We studied 28 children, ages 12 to 48 mo, after a 7-d home adaptation to a diet representative of their usual daily mineral intake. A multi-tracer stable isotope study was performed to assess iron absorption both from a meal ((58)Fe) and from a reference iron dose ((57)Fe) given with ascorbic acid without a meal. Iron intake was 6.9 +/- 2.4 mg, approximately the 35th percentile of typical U.S. intakes. Absorption of (58)Fe was related to serum ferritin (r(2) = 0.319, P = 0.0018) and more so to reference dose iron absorption (r(2) = 0.653, P < 0.0001). Iron absorption was negatively correlated with zinc intake (r(2) = 0.090, P = 0.0049) but was not correlated with iron intake (P = 0.20). However, zinc intake was not correlated with measures of iron status, including reference dose iron absorption and serum ferritin (r(2) < 0.1, P > 0.25). Total absorbed iron was similar to needs estimated by the Institute of Medicine. We conclude that iron absorption in young children is more closely related to iron status than to iron intake. Reference dose iron absorption may be superior to serum ferritin as a surrogate measure for iron status in this age group. Although zinc intake may affect iron absorption from a meal, it does not appear to have a detectable effect on overall iron status in otherwise well-nourished children.     

Zinc Absorption from Micronutrient Powder Is Low but Is not Affected by Iron in Kenyan Infants

Interference with zinc absorption is a proposed explanation for adverse effects of supplemental iron in iron-replete children in malaria endemic settings. We examined the effects of iron in micronutrient powder (MNP) on zinc absorption after three months of home fortification with MNP in maize-based diets in rural Kenyan infants. In a double blind design, six-month-old, non-anemic infants were randomized to MNP containing 5 mg zinc, with or without 12.5 mg of iron (MNP + Fe and MNP − Fe, respectively); a control (C) group received placebo powder. After three months, duplicate diet collections and zinc stable isotopes were used to measure intake from MNP + non-breast milk foods and fractional absorption of zinc (FAZ) by dual isotope ratio method; total absorbed zinc (TAZ, mg/day) was calculated from intake × FAZ. Mean (SEM) TAZ was not different between MNP + Fe (n = 10) and MNP − Fe (n = 9) groups: 0.85 (0.22) and 0.72 (0.19), respectively, but both were higher than C (n = 9): 0.24 (0.03) (p = 0.04). Iron in MNP did not significantly alter zinc absorption, but despite intakes over double estimated dietary requirement, both MNP groups’ mean TAZ barely approximated the physiologic requirement for age. Impaired zinc absorption may dictate need for higher zinc doses in vulnerable populations.     

山东省农村育龄妇女代表性膳食下铁、锌、钙吸收率分析

目的:研究山东省农村育龄妇女代表性膳食下铁、锌、钙的吸收率,以及膳食因素对它们吸收利用的影响。方法:用代谢平衡法,使用原子吸收分光光度计(AAS)测定膳食与粪便的铁、锌、钙,计算铁、锌、钙的吸收率。同时测定影响铁、锌、钙吸收的因子:膳食脂肪、蛋白、植酸、纤维素和VitC的含量,计算日平均摄入量,将其结果与我国育龄妇女每日推荐膳食营养素摄入量(RNI)进行比较。结果:铁、锌、钙的吸收率分别为8·26%、21·48%、47·94%,铁的平均日摄入量为13·77mg,占RNI的68·85%,远低于推荐量,锌的平均日摄入量为15·43mg,占RNI的102·87%,高于推荐量,钙的平均日摄入量为409·38mg,占RNI的51·17%,远低于推荐量。蛋白质和VitC的日摄入量分别为65·70g与34·20mg,占RNI的82·12%~109·50%和34·20%,低于推荐量。脂肪、植酸和膳食纤维的摄入量较高。结论:在蛋白质和抗坏血酸的日摄入量较低,脂肪、植酸和膳食纤维的摄入量较高的条件下,铁吸收率较低,铁营养缺乏,锌营养尚可,钙摄入量显著低于RNI,显示钙摄入严重不足。     

Effects of high compared with low calcium intake on calcium absorption and incorporation of iron by red blood cells in small children.

BACKGROUND: The potential benefits of increasing calcium intake in small children must be balanced with the potential risk to iron utilization from high calcium intakes. OBJECTIVE: This study was designed to evaluate the relation between calcium intake and calcium absorption and iron incorporation into red blood cells. DESIGN: We performed a multitracer, crossover study of the absorption of calcium and red blood cell incorporation of iron in 11 preschool children aged 3-5 y who had been adapted for 5 wk to low- (502 +/- 99 mg) and high- (1180 +/- 117 mg) calcium diets. Stable-isotope studies were performed by using 44Ca and 58Fe given orally with meals and 46Ca given intravenously. RESULTS: Iron incorporation into red blood cells 14 d postdosing was similar (6.9 +/- 4.2% compared with 7.9 +/- 5.5%; NS) with the low- and high-calcium diets, respectively. Total calcium absorption (181 +/- 50 compared with 277 +/- 91 mg/d; P = 0.002) was greater in children with the higher calcium intake. CONCLUSIONS: Our findings indicate that small children may benefit from calcium intakes similar to those recommended for older children without adverse effects on dietary iron utilization.     

Metabolic adaptations to low zinc intakes in premenarcheal girls

BACKGROUND: Zinc deficiency is increasingly recognized as an important cause of mortality and morbidity. Children in developing countries are at especially high risk because of relatively low zinc intakes and poor bioavailability. OBJECTIVE: We assessed the effect of 2-wk adaptation to low zinc intake (4 mg/d) on fractional zinc absorption, endogenous fecal zinc excretion, and urinary zinc excretion. DESIGN: Sixteen healthy 9-14-y-old girls were studied twice in random order after 2-wk adaptation to diets providing either 12 mg/d (high) or 4 mg/d (low) zinc. Fractional zinc absorption and endogenous fecal zinc excretion were measured with use of established stable isotope techniques. RESULTS: Plasma zinc was not significantly lower during the low dietary intake period (1.06 +/- 0.18 mg/L) than during the high dietary intake period (1.14 +/- 0.23 mg/L, P = 0.30). Endogenous fecal zinc excretion was significantly lower during the low intake period (1.08 +/- 0.62 mg/d) than during the high intake period (1.82 +/- 0.95 mg/d, P < 0.026), but there was no significant change in fractional zinc absorption (30.6% +/- 12.4% compared with 26.6% +/- 9.0%, P = 0.32) or urinary zinc excretion (0.68 +/- 0.35 mg/d compared with 0.59 +/- 0.24 mg/d, P = 0.30). Approximate zinc balance was significantly lower during the low-intake period than during the high-intake period (P = 0.007) and significantly (P < 0.0001) less than zero. CONCLUSION: Short-term zinc restriction in premenarcheal girls leads to a significant decrease in endogenous fecal zinc excretion, which was inadequate to restore normal zinc balance.     

Dietary intake and iron status of Australian vegetarian women.

BACKGROUND: Despite the possible overall health benefits of a vegetarian diet, there is concern that some vegetarians and infrequent meat eaters, particularly females, may have inadequate iron status because of low or no heme-iron intakes. OBJECTIVE: The objective was to investigate the nutritional intake and iron status of vegetarian women. DESIGN: The nutritional intakes of 50 free-living vegetarian women aged 18-45 y and 24 age-matched omnivorous control women were assessed by using 12-d weighed dietary records. Iron status was assessed by measuring hemoglobin and serum ferritin concentrations. RESULTS: There was no significant difference between mean (+/-SD) daily iron intakes of vegetarians and omnivores (10.7 +/- 4.4 and 9.9 +/- 2.9 mg, respectively), although heme-iron intakes were low in the vegetarians. Vegetarians had significantly lower intakes of protein (P < 0.01), saturated fat (P < 0.01), and cholesterol (P < 0.001), and significantly higher intakes of dietary fiber (P < 0.001) and vitamin C (P < 0.05). Mean serum ferritin concentrations were significantly lower (P = 0.025) in vegetarians (25.0 +/- 16.2 microg/L) than in omnivores (45.5 +/- 42.5 microg/L). However, similar numbers of vegetarians (18%) and omnivores (13%) had serum ferritin concentrations <12 microg/L, which is a value often used as an indicator of low iron stores. Hemoglobin concentrations were not significantly different. CONCLUSION: It is important that both vegetarian and omnivorous women maintain an adequate iron status and follow dietary practices that enhance iron absorption.     

Iron, zinc, and alcohol consumption and mortality from cardiovascular diseases: the Iowa Women's Health Study

BACKGROUND: The relation between iron status and atherosclerosis has long been a topic of debate. OBJECTIVE: We examined associations of cardiovascular disease (CVD) mortality with dietary intakes of iron (a possible prooxidant), zinc (a possible antioxidant), and alcohol (a disruptor of iron homeostasis). DESIGN: Postmenopausal women (n = 34 492) aged 55-69 y at baseline, who completed a food-frequency questionnaire, were followed for CVD mortality over 15 y. RESULTS: Among women who consumed >/=10 g alcohol/d, after adjustment for CVD risk factors in a model that contained dietary heme iron, nonheme iron, and zinc intakes, dietary heme iron showed a positive association, dietary nonheme iron showed a U-shaped association, and dietary zinc showed an inverse association with CVD mortality. For example, the relative risks (RRs) for categories of dietary heme iron were 1.0, 1.46, 1.52, 1.73, and 2.47 (P for trend = 0.04); corresponding RRs for dietary nonheme iron were 1.0, 0.93, 0.63, 0.83, and 1.20 (P for quadratic term = 0.02). The corresponding RRs for dietary zinc were 1.0, 0.61, 0.59, 0.57, and 0.37 (P for trend = 0.07). In an analysis restricted to those who consumed >/=30 g alcohol/d, the risk gradients strengthened. CONCLUSIONS: Our results suggest that a higher intake of heme iron might be harmful, whereas a higher intake of zinc might be beneficial in relation to CVD mortality in the presence of a trigger that can disturb iron homeostasis, such as alcohol consumption.     

Heme-iron absorption is saturable by heme-iron dose in women

In developed countries where meat is an important constituent of the diet, much of the dietary iron is in the heme-iron form as hemoglobin and myoglobin. Heme-iron is absorbed more efficiently than inorganic iron by the human intestine. Thus, it is important to know how the dose of heme-iron affects iron absorption. The purpose of this study was to establish the dose-effect of heme-iron on the percentage and absolute amount of iron absorbed. Twenty-seven healthy women (28- to 50-y-old) were selected to participate in two iron absorption studies. Through the use of iron isotopes ((59)Fe and (55)Fe), the studies were performed to characterize the dose-response curve of non-heme-iron absorption (ferrous sulfate), and to establish the dose-response curve of heme-iron absorption (hemoglobin). The labeled hemoglobin was prepared by use of red blood cells from rabbits. The geometric means (+/-1 SEM range) of non-heme iron absorbed were 0.2 (0.2-0.3), 1.2 (1.0-1.5), 6.7 (5.7-8.0) and 13.0 (11.5-14.6) mg of iron for doses of 0.5, 5, 50 and 100 mg of iron as ferrous sulfate, respectively; and 0.1 (0.1-0.2), 0.4 (0.3-0.4), 2.2 (2.0-2.4) and 2.2 (1.7-3.0) mg of iron for doses of 0.5, 3, 15 and 30 mg of heme-iron as hemoglobin, respectively. The fitted curves for heme and non-heme iron differed (P < 0.04). These results strongly suggest that the heme-iron absorption pathway is saturable.     

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.     

Heme and non-heme iron consumption and risk of gallstone disease in men

BACKGROUND: Excessive iron intake can promote biliary cholesterol crystal formation in experimental studies. The absorption of heme iron is more complete than that of non-heme iron in humans; however, the effect of long-term consumption of heme and non-heme iron on the risk of gallstones is unknown. OBJECTIVE: The objective of the study was to examine long-term iron intake in relation to the occurrence of gallstone disease. DESIGN: We prospectively studied intakes of heme and non-heme iron and the risk of gallstone disease in a cohort of 44 758 US men from 1986 to 2002. Iron consumption was assessed by using a validated semiquantitative food-frequency questionnaire. Newly diagnosed gallstone disease was ascertained biennially. RESULTS: We documented 2468 incident cases of symptomatic gallstones during 597 699 person-years of follow-up. The age-adjusted relative risks (RRs) for men with intakes of heme iron and non-heme iron, when the highest and lowest quintiles were compared, were 1.21 (95% CI: 1.06, 1.37; P for trend = 0.0008) and 1.02 (95% CI: 0.90, 1.16; P for trend = 0.45), respectively. After adjustment for multiple potential confounding variables, when extreme quintiles were compared, the multivariate RR of heme iron intake was not significantly changed and remained significant with a dose-response relation (RR = 1.21; 95% CI: 1.03, 1.42; P for trend = 0.01), and that of non-heme iron intake was not significant (RR = 1.14; 95% CI: 0.99, 1.31; P for trend = 0.18). CONCLUSION: Our findings suggest that a higher consumption of heme iron is associated with a greater risk of gallstone disease among men.     

Interaction among heme iron, zinc, and supplemental vitamin C intake on the risk of lung cancer: Iowa Women's Health Study

Redox-active iron present at physiological levels in the pulmonary epithelial lining fluid may lead to damage of lung tissue under some circumstances. For example, factors that increase potential for oxidative stress, such as higher intake of heme iron or higher intake of vitamin C in the presence of high intake of iron, might increase the risk of lung cancer, whereas higher intake of the antioxidant zinc might decrease that risk. During 16 yr of follow-up, 34,708 postmenopausal women, aged 55-69 yr at baseline who completed a food-frequency questionnaire for the Iowa Women's Health Study, were followed for 700 incident lung cancers. When subjects were stratified by intake of vitamin C supplements, among women who took vitamin C supplements of >500 mg/day, after adjusting for age, total energy intake, cigarette smoking, alcohol consumption, and dietary zinc or dietary heme iron intake, relative risks across categories of dietary heme iron intake were 1.0, 0.85, 0.93, 1.32, 1.70, and 3.77 (P for trend = 0.05; P for interaction = 0.08), whereas corresponding figures for dietary zinc intake were 1.0, 1.15, 0.71, 0.84, 0.61, and 0.11 (P for trend = 0.12; P for interaction = 0.04). The strength of the associations of heme iron and zinc intake with lung cancer appeared to be stronger with increasing levels of vitamin C supplement intake. Our results suggest that high dietary heme iron intake may increase the risk of lung cancer, whereas high dietary zinc may decrease the risk of lung cancer among postmenopausal women who consume high-dose vitamin C supplements. This finding may be of particular importance to smokers, for whom vitamin C supplementation is a common recommendation.     

Iron absorption in breast-fed infants: effects of age,iron status,iron supplements,and complementary foods

BACKGROUND: Iron supplements are often recommended for older breast-fed infants, but little is known about factors affecting iron absorption from human milk or supplements. OBJECTIVE: We investigated the effects of age, iron status, and iron intake on iron absorption in healthy, term, breast-fed infants. DESIGN: Twenty-five infants were randomly assigned to receive either 1) iron supplements (1 mg x kg(-1) x d(-1)) from 4 to 9 mo of age, 2) placebo from 4 to 6 mo and iron supplements from 6 to 9 mo, or 3) placebo from 4 to 9 mo. Infants were exclusively breast-fed to 6 mo and partially breast-fed to 9 mo of age. Iron absorption was assessed by giving (58)Fe with mother's milk at 6 and 9 mo. Blood samples were obtained at 4, 6, and 9 mo, and complementary food intake was recorded at 9 mo. RESULTS: At 6 mo, mean (+/-SD) fractional iron absorption from human milk was relatively low (16.4 +/- 11.4%), with no significant difference between iron-supplemented and unsupplemented infants. At 9 mo, iron absorption from human milk remained low in iron-supplemented infants (16.9 +/- 9.3%) but was higher (P = 0.01) in unsupplemented infants (36.7 +/- 18.9%). Unexpectedly, iron absorption at 9 mo was not correlated with iron status but was significantly correlated with intake of dietary iron, including supplemental iron. CONCLUSIONS: Changes in the regulation of iron absorption between 6 and 9 mo enhance the infant's ability to adapt to a low-iron diet and provide a mechanism by which some, but not all, infants avoid iron deficiency despite low iron intakes in late infancy.     

Prenatal iron supplements impair zinc absorption in pregnant Peruvian women

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 from wk 10-24 of pregnancy until delivery. Supplements contained 60 mg of Fe and 250 microg 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 ((67)Zn) and intravenous ((70)Zn) stable zinc isotopes. Percentage zinc absorption was significantly lower than controls in fasting women receiving iron- containing prenatal supplements (20.5 +/- 6.4 vs. 20.2 +/- 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 micromol/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 of both these nutrients.     

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.     

Meat and meat products consumption in Italy: contribution to trace elements, heme iron and selected B vitamins supply

This study was undertaken to estimate the contribution of meat and meat products consumption to the daily intakes of trace elements (Fe, Zn, Cu, Se), heme iron, and selected B vitamins (thiamine, riboflavin, niacin) in Italy. Meat and meat products were selected on the basis of their consumption frequency reported by the most recent nationwide dietary individual survey carried out in Italy (INN-CA study). The daily intakes of total iron and heme iron were 1.65 and 1.13 mg/person/day. Zinc intake was 3.65 mg/person/day. Beef made the main contribution to iron, heme iron, and zinc daily intakes. Copper daily intake was 107.3 microg/person/day, with meat products provided the highest contribution (40 microg/person/day). Daily intake of selenium (7.14 microg/person/day) was provided mainly by poultry consumption. Thiamine intake was 228 microg/person/day, and meat products were the main source (110 microg/person/day). Riboflavin intake was 136 microg/person/day, with both beef and meat products as the main contributors (40 microg/person/day). Niacin intake was 7.53 mg/person/day, and poultry was the main source (2.28 mg/person/day). Meat and meat products were a valuable source of micronutrients, supplying 47, 48, and 24% of zinc, niacin, and thiamin daily requirements, respectively, and over 10% of iron, copper, selenium, and riboflavin daily average requirement values of the italian RDAs calculated for the population involved in the survey (INN-CA study).     

Demonstrating zinc and iron bioavailability from intrinsically labeled microencapsulated ferrous fumarate and zinc gluconate Sprinkles in young children

Nutrient-nutrient interactions are an important consideration for any multiple-micronutrient formulation, including Sprinkles, a home-fortification strategy to control anemia. The objectives of this randomized controlled trial were as follows: 1) to compare the absorption of zinc at 2 doses given as Sprinkles; and 2) to examine the effect of zinc and ascorbic acid (AA) on iron absorption from Sprinkles. Seventy-five children aged 12-24 mo were randomly assigned to the following groups: 1) 5 mg of labeled zinc (67Zn) with 50 mg AA (LoZn group); b) 10 mg of labeled zinc (67Zn) with 50 mg AA (HiZn group); or 3) 5 mg zinc with no AA (control). All groups contained 30 mg of labeled iron (57Fe). Intravenous infusions labeled with 70Zn (LoZn and HiZn groups) and 58Fe (control) were administered. Blood was drawn at baseline, 48 h and 14 d later. The percentage of zinc absorbed did not differ between LoZn (geometric mean = 6.4%; min-max: 1.7-14.6) and HiZn (geometric mean = 7.5%; min-max: 3.3-18.0) groups. However, total zinc absorbed was significantly different between the LoZn (geometric mean = 0.31 mg; min-max: 0.08-0.73) and HiZn (geometric mean = 0.82 mg; min-max: 0.33-1.82) groups (P = 0.0004). Geometric mean percentage iron absorption values did not differ between the LoZn (5.9%; min-max: 0.8-21) and HiZn (4.4%; min-max: 0.6-12.3) groups and between the LoZn and control groups (5.0%; min-max: 1.4-24). We conclude that zinc in the form of Sprinkles has a low bioavailability, yet provides adequate amounts of absorbed zinc in young children, and that there is no effect of zinc or AA on iron absorption from the given formulations of Sprinkles.     

云南大红山铜矿区成年居民铜、铁、锌血清水平和膳食摄入量

目的 了解云南大红山铜矿成年居民铜、铁、锌的血清水平和膳食摄入量.方法 在大红山矿区随机抽取180名成年居民,采用原子吸收分光光度法检测血清铜、铁、锌水平.从180人中随机抽取60人,采刚化学分析法调查膳食铜、铁、锌摄入量.结果 171人的血清铜、铁、锌水平分别为（0.90±0.18）、（1.25±0.93）、（0.75±0.28）mg/L,血清铜和铁呈显著负相关（r=-0.26,P＜0.001）.血清铜与年龄呈显著正相关（r=0.25,P＜0.001）,女性血清铜水平明显高于男性（P=0.011）.60人的膳食铜、铁、锌摄入量分别为（1.74±1.09）、（16.29±10.73）、（7.56±3.38）mg/d,女性均明显低于男性（P＜0.05）.血清铜、铁、锌水平和膳食摄入量均存在地区差异.结论 云南大红山矿区成年居民血清铜、铁水平均正常,血清锌水平偏低.铜、铁、锌的膳食摄入量均未超过可耐受最高摄人量,且部分人摄入量偏低.     

Na2EDTA enhances the absorption of iron and zinc from fortified rice flour in Sri Lankan children

Rice flour was proposed as a vehicle for iron and zinc fortification in Sri Lanka. Although widely consumed, rice flour has not been evaluated as a fortified food, and the absorption of minerals including iron and zinc from this flour is unknown. Determination of the bioavailability of these nutrients is a critical step before commencing a fortification program. We randomly divided 53 Sri Lankan schoolchildren ages 6-10 y into 4 groups that consumed a local dish prepared with 25 g of fortified rice flour labeled with one of the following: 1) (58)FeSO(4) 2) (58)FeSO(4) + Na(2)EDTA 3) (58)FeSO(4) + (67)ZnO or, 4) (58)FeSO(4) + Na(2)EDTA + (67)ZnO. The levels of iron and zinc were 60 mg/kg; the rice flour also contained folate at 2 mg/kg in each group. Na(2)EDTA was added at a Fe:Na(2)EDTA, 1:1 molar ratio. A total of 48 children completed the trial. Absorption of (58)Fe from a meal was significantly greater (P < 0.01) in the groups administered FeSO(4) + Na(2)EDTA (4.7 +/- 3.6%) than in those administered FeSO(4) without Na(2)EDTA (2.2 +/- 1.3%). Fractional absorption of zinc was 13.5 +/- 6.0% in the FeSO(4) + Na(2)EDTA group and 8.8 +/- 2.0% in the FeSO(4) group (P = 0.037). Although zinc absorption was low, our results demonstrated a benefit in using Na(2)EDTA to improve both iron and zinc absorption. We conclude that the fortification of rice flour is feasible, although additional strategies such as dephytinization or an increase in the level of iron and zinc fortification should be considered to obtain a higher proportion of the daily requirement of total absorbed iron and zinc.     

Longitudinal measurements of zinc absorption in Peruvian children consuming wheat products fortified with iron only or iron and 1 of 2 amounts of zinc

BACKGROUND: Information is needed on the fractional absorption of zinc (FAZ) and absorbed zinc (AZ) during prolonged exposure to zinc-fortified foods. OBJECTIVE: The objective was to measure FAZ and AZ from diets fortified with different amounts of zinc and to determine whether zinc absorption changes over approximately 7 wk. DESIGN: Forty-one stunted, moderately anemic children received daily, at breakfast and lunch, 100 g wheat products fortified with 3 mg Fe (ferrous sulfate) and 0 (group Zn-0), 3 (group Zn-3), or 9 (group Zn-9) mg Zn (zinc sulfate) per 100 g flour. FAZ was measured on days 2-3 and 51-52; meal-specific AZs were calculated as the product of FAZ and zinc intake. RESULTS: For the breakfast and lunch meals combined, mean total zinc intakes were 2.14, 4.72, and 10.04 mg/d in groups Zn-0, Zn-3, and Zn-9, respectively, during the initial absorption studies; mean (+/-SD) FAZ values were 0.341 +/- 0.111, 0.237 +/- 0.052, and 0.133 +/- 0.041, respectively, on days 2-3 (P < 0.001) and did not change significantly on days 51-52 in the subset of 31 children studied twice. Mean initial AZ was positively related to zinc intake (0.71 +/- 0.18, 1.11 +/- 0.21, and 1.34 +/- 0.47 mg/d, respectively; P < 0.001); final values did not differ significantly from the initial values. CONCLUSIONS: AZ from meals containing zinc-fortified wheat products increases in young children relative to the level of fortification and changes only slightly during approximately 7-wk periods of consumption. Although consumption of zinc-fortified foods may reduce FAZ, zinc fortification at the levels studied positively affects total daily zinc absorption, even after nearly 2 mo of exposure to zinc-fortified diets.     

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.