Factors affecting iron absorption and the role of fortification in enhancing iron levels

Iron is an important micronutrient required for a number of biological processes including oxygen transport, cellular respiration, the synthesis of nucleic acids and the activity of key enzymes. The World Health Organization has recognised iron deficiency as the most common nutritional deficiency globally and as a major determinant of anaemia. Iron deficiency anaemia affects 40% of all children between the ages of 6 and 59 months, 37% of mothers who are pregnant and 30% of women between the ages of 15 and 49 years worldwide. Dietary iron exists in two main forms known as haem iron and non-haem iron. Haem iron is obtained from animal sources such as meat and shows higher bioavailability than non-haem iron, which can be obtained from both plant and animal sources. Different components in food can enhance or inhibit iron absorption from the diet. Components such as meat proteins and organic acids increase iron absorption, while phytate, calcium and polyphenols reduce iron absorption. Iron levels in the body are tightly regulated since both iron overload and iron deficiency can exert harmful effects on human health. Iron is stored mainly as haemoglobin and as iron bound to proteins such as ferritin and hemosiderin. Iron deficiency affects individuals at increased risk due to factors such as age, pregnancy, menstruation and various diseases. Different solutions for iron deficiency are applied at individual and community levels. Iron supplements and intravenous iron can be used to treat individuals with iron deficiency, while various types of iron-fortified foods and biofortified crops can be employed for larger communities. Foods such as rice, flour and biscuits have been used to prepare fortified iron products. However, it is important to ensure the fortification process does not exert significant negative effects on organoleptic properties and the shelf life of the food product.     

The G277S transferrin mutation does not affect iron absorption in iron deficient women

Background Iron deficiency anaemia is one of the most important nutritional diseases, with high prevalence worldwide. The G277S transferrin mutation has been implicated as a risk factor for iron deficiency in menstruating women. However, the subject is controversial and there are no data concerning the possible influence of this polymorphism on iron absorption. Aim of the study To undertake a pilot study to investigate the effect of carrying the G277S transferrin mutation on non-haem iron absorption from a meal in young menstruating women compared to wild-type controls. Methods Menstruating women with low iron stores (serum ferritin < 30 μg/l) or who had suffered from iron deficiency anaemia or had a family history of anaemia were recruited (n = 162). Haematological parameters were analysed, including haemoglobin, ferritin, total-iron binding capacity and transferrin saturation. Non-haem iron absorption from a meal was measured in 25 non-anaemic women either with the G277S/G277G (n = 10) or the wild type G277G/G277G (n = 15) genotype. The incorporation of stable isotopes of iron into erythrocytes was used to measure absorption. Results and Conclusions There were no significant differences in iron status indices or non-haem iron absorption between genotypes. However, G277S carriers did not show the usual inverse association between iron stores and non-haem iron absorption. Further studies should focus on the effects of a combination of polymorphisms in iron metabolism genes on iron absorption.     

双标稳定性同位素测定微量元素吸收率

迄今为止 ,测定微量元素吸收率较准确的方法依然是同位素法。由于放射线同位素的危害性 ,使得放射线同位素在某些人群中的应用受到限制。随着稳定性同位素技术的发展 ,应用稳定性同位素来研究微量元素的吸收和利用成为近年来在微量元素营养研究中的热点。特别是双标稳定性同位素技术更以其准确性高而受到微量元素学家的关注。然而目前普遍使用的计算方法多数以估计的机体血液体积及血红蛋白掺入率为基础 ,从而人为地引入了误差。为了更为有效地利用已有资料、准确地计算微量元素的生物利用 ,在前人工作的基础上 ,作者在本文对使用双标稳定性同位素技术测定微量元素的吸收率的方法进行了较为详细地讨论 ,对该方法的理论假设、实验方法、所需的基础数据、计算思路及其具体的计算过程都作了具体的说明。本文所介绍的方法可方便地用于具体的实验中     

Resistant Starch Production and Glucose Release from Pre‐Prepared Chilled Food: The SPUD Project

With an increasing prevalence of diabetes worldwide, effective dietary strategies for blood glucose control are crucial. As carbohydrates make up approximately 50% of the diet, it is neither practical nor advisable to avoid them altogether. Most of the carbohydrate in the diet is derived from starch, found in potatoes, pasta, rice and bread. These foods are often processed in some way before consumption, yet little is known about the effects processing, such as chilling and reheating, has on the glycaemic response, particularly when the food is consumed in the context of a mixed meal. This article introduces the SPUD project, a BBSRC DRINC‐funded initiative. Taking the potato as the model carbohydrate, this project will investigate, via in vitro and in vivo studies, the effects of domestic food processing techniques on the glycaemic response. A final study, utilising intrinsically labelled potato and a dual stable isotope methodology, will model glucose flux data to determine the underlying mechanisms of action.     

铁缺乏症婴幼儿认知水平研究

目的 了解非贫血铁缺乏症和缺铁性贫血婴幼儿的认知水平, 为进一步治疗提供科学依据。方法 采用Gesell发育测试法评估非贫血铁缺乏症和缺铁性贫血婴幼儿适应性、大运动、精细动作、语言和个人社交5个能区发育水平。结果 患铁缺乏症的男婴较女婴更多(χ²=13.06, P=0.001), 非贫血铁缺乏症(non-anemia iron deficiency, NAID)组、缺铁性贫血(iron deficiency anemia, IDA)组较铁充足(iron sufficiency, IS)组婴幼儿的5个能区发育水平落后(F_适应性=13.64;F_大运动=6.24;F_精细动作=6.25;F_语言=4.89;F_个人社交=9.14, P值均<0.01), NAID和IDA婴幼儿之间差异无统计学意义;但男性婴幼儿在语言和个人社交发育商分数较女婴更低(F=9.299, P=0.003;F=4.250, P=0.042)。结论 铁缺乏症伴或不伴贫血对婴幼儿的认知水平都有影响, 提示在临床工作中应早期干预铁缺乏。     

Cooking and Fe Fortification Have Different Effects on Fe Bioavailability of Bread and Tortillas

Objective: To identify iron sources for wheat- (WF) and corn-flour (CF) fortification taking into account the effect of cooking.

Methods: Sixty-six Fe-depleted rats were replete with various Fe sources. Fe bioavailability and utilization in wheat bread (WB) and corn tortillas (CT) fortified with various Fe sources was assessed after the depletion and repletion periods.

Results: Baking decreased the phytates content of WF by 97%. Improvements in Hb and FeHb were greater in rats fed unfortified WB than in those fed unfortified WF. Fe fortification had no benefit. In contrast, phytates content was unchanged by tortilla preparation, but fortification improved iron availability. Iron bioavailability indicators were best in rats fed CT fortified with ferrous sulfate and NaFe(III)EDTA than in those fed unfortified CT or CT plus reduced Fe.

Conclusion: We concluded that baking WF bread improved the bioavailability of native Fe with no further effect of fortification. Pan-cooking of lime-treated CF did not improve Fe bioavailability, but addition of Ferrous sulfate or NaFe(III)EDTA did it, despite the high phytate and calcium content of tortillas.     

Child Food Insecurity and Iron Deficiency Anemia in Low-Income Infants and Toddlers in the United States

Objective: Examine the association between child-level food insecurity and iron status in young children utilizing community-based data from the Children's Sentinel Nutrition Assessment Program (C-SNAP). Methods: A cross-sectional sample of caregivers of children ≤36 months of age utilizing emergency department (ED) services were interviewed between 6/96–5/01. Caregiver interviews, which included questions on child-level food security, were linked to a primary clinic database containing hemoglobin, red blood cell distribution width, mean corpuscular volume, free erythrocyte protoporphyrin and lead values. Children a priori at-risk for anemia: birthweight ≤2500 g, with HIV/AIDS, sickle cell disease, or lead values ≥10.0 ug/dL, and children ≤6 months of age were excluded from the analysis. Only laboratory tests 365 days prior or 90 days after interview were examined. Iron status was classified in four mutually exclusive categories: 1) Iron Sufficient-No Anemia (ISNA), 2) Anemia (without iron deficiency), 3) Iron Deficient-No Anemia (IDNA), 4) Iron Deficient with Anemia (IDA). Results: 626 ED interviews linked to laboratory data met the inclusion criteria. Food insecure children were significantly more likely to have IDA compared to food secure children [Adjusted Odds Ratio = 2.4, 95% CI (1.1–5.2), p = 0.02]. There was no association between child food insecurity and anemia without iron deficiency or iron deficiency without anemia. Conclusion: These findings suggest an association between child level food insecurity and iron deficiency anemia, a clinically important health indicator with known negative cognitive, behavioral and health consequences. Cuts in spending on food assistance programs that address children's food insecurity may lead to adverse health consequences.Presented at the Pediatric Academic Soceity Meeting, Abstract No. 2668 held April 28, 2001 in Baltimore, MD.     

稳定性同位素示踪测定NaFeEDTA强化酱油中铁在人体中吸收率

采用铁稳定性同位素54Fe和58Fe分别标记FeSO4及NaFeEDTA并以稀土元素 (Dy)作为排泄物回收标记物。自愿受试人群为 18～ 2 2岁健康女性。采用我国典型城镇成年女性膳食模式。两种铁剂及Dy以酱油为食物载体一同分 2日 6次经口给入。实验其间每日留取受试人膳食样品并完全收集受试人在实验期的排泄物。采用原子吸收和ICP -MS分别检测膳食及排泄物中总铁含量和铁同位素比例 ,对两种铁剂中的铁的吸收率进行比较。结果表明 ,FeSO4中铁在人体中的平均吸收率为 4 73% ,NaFeEDTA为 10 5 1%。二者差异为极显著(P <0 0 1)。说明NaFeEDTA中铁的吸收率优于FeSO4。     

Spatial and Temporal Trends of Mercury Concentrations in Young-of-the-Year Spottail Shiners (<Emphasis Type="Italic">Notropis hudsonius</Emphasis>) in the St. Lawrence River at Cornwall,ON

The St. Lawrence River at Cornwall, Ontario is an “Area of Concern” because of mercury (Hg) biomagnification from bottom sediments. To assess the spatial and temporal distribution of Hg in the food web, young-of-the-year (YOY) spottail shiners (Notropis hudsonius) were collected in August 2005 from five sites along the Cornwall waterfront within a Hg-contaminated zone and two reference zones. The results were compared to analyses made between 1979 and 2000 by the Ontario Ministry of the Environment. Total Hg concentrations in spottail shiners from the contaminated zone were significantly higher than in reference zones, confirming previous observations. Within the contaminated zone, there were significant differences in Hg concentrations among three sites spaced about 500 m apart, consistent with a high degree of site fidelity of YOY fish and suggesting a possible internal source of Hg. Hg concentrations in spottail shiners are decreasing regionally, although year-to-year variability was high, particularly in the contaminated zone. Stable isotope analyses of spottail shiners did not reveal any differences in nitrogen isotope composition among zones that would indicate differences in food-web structure and Hg biomagnification. However, carbon sources at an upstream reference zone were not the same as within the Area of Concern. Differences in carbon isotope composition at two sites within the contaminated zone corresponded to differences in Hg concentrations, consistent with a unique internal source of Hg. The variation in Hg contamination of YOY spottail shiners over fine spatial and temporal scales provide important insights about the potential release of Hg from contaminated sediments and the role of climate in regional trends. Sessile YOY fish provide a precise indicator for demonstrating these differences and for assessing their cause.     

大豆粉铁对贫血大鼠血红蛋白恢复效应的相对生物利用率

为澄清文献上关于大豆制品不利于膳食铁生物利用率的有争论的观点,本文以硫酸亚铁为参考铁源,某厂试制的猪血粉铁为比照铁,面粉为载体,通过血大鼠模型血红蛋白恢复效应,研究了大豆粉铁的相对生物利用率(RBA％)。实验结果表明:当恢复饲料中3/4 (24/32ppm)铁来自大豆粉、大豆粉面粉各半、猪血粉面粉各半、猪血粉和硫酸亚铁时,贫血大鼠在五周恢复期间血红蛋白恢复效应顺次分别是(g％):6.6至9.4;7.0至10.4;6.1至11.1;6.4至11.4和5.3至12.8。各组铁的相对生物利用率顺次分別为45.4、65.0、72.0、74.0和100％。大豆粉铁的相对生物利用率最低。本文并就此提出一些讨论意见。     

铁与儿童精神运动发育、认知功能和神经行为关系的研究进展

铁是大脑新陈代谢的基本元素,缺铁可引起神经递质稳态的改变、减少髓鞘的产生、损害突触的形成、并使基底神经节功能下降,因此,缺铁性贫血会对精神运动发育、认知功能和神经行为产生不利影响,危害婴幼儿的健康发育。了解铁缺乏与精神运动发育、认知功能和神经行为的关系,弄清补充铁的疗效并在儿童保健时开展血清铁含量检验,对制定早期预防铁缺乏的公共卫生策略具有十分重要的意义。     

Influence of dietary and socio-demographic factors on the iron status of married adolescent girls from Indian urban slums

To explore the influence of dietary factors of iron bioavailability and socio-demographic conditions on blood iron status of married adolescent girls (MAG), a cross-sectional study was conducted in 173 MAG (15–19 years old) from urban slums near Pune city, India. Diet was assessed by two random 24-h recalls. The age, weight, height, education, family size, income, physical work, and number of days of menstrual loss were recorded. Fasting blood was analyzed for hemoglobin and serum ferritin. Mean intakes of micronutrients were 40–75% less than the recommended dietary intakes for Indian adolescent girls. High intake of phytates (171±6 mg/day) and low intakes of vitamin C (25±1 mg/day) resulted in low bioavailable iron intakes. The mean bioavailable iron intake was 0.76±0.3 mg/day, which is one-half of the basal iron requirement of adolescent girls. The prevalence of iron deficiency (serum ferritin<12 µg/l) was 25.1%, and anemia (hemoglobin <12 g/l) was seen in 46.4% of MAG. A multiple regression model adjusted for energy intake indicated that intakes of β-carotene and riboflavin were associated with hemoglobin (P<0.001) and those of zinc, riboflavin and thiamin associated with serum ferritin (P<0.01). Multiple regressions including socio-demographic factors revealed that the family size, number of menstrual days lost and total bioavailable iron intake were the influencing factors for low iron status. In conclusion, there is a need to increase intakes of vitamin C and other micronutrients of the MAGs and to improve iron bioavailability through diet modifications.     

用双标稳定同位素技术分析乳糖酶缺乏者小肠粘膜乳糖酶活性

目的　应用双标稳定同位素1 3C 乳糖2 H 葡萄糖负荷试验对乳糖酶缺乏者小肠粘膜乳糖酶活性进行定量分析。方法　选用4 3名乳糖酶缺乏者(呼气ΔH2 浓度>2 0 μmol mol)作为实验对象,根据乳糖不耐受症状记录分为乳糖吸收不良组(LM)和乳糖不耐受组(LI)。以2 5g1 3C 乳糖和0 . 5g2 H 葡萄糖作为受试底物,分析受试者摄入底物之后各时点血浆中总葡萄糖、1 3C 葡萄糖和2 H 葡萄糖浓度,并计算各时点1 3C 葡萄糖2 H 葡萄糖吸收百分率的比值,以4 5min、6 0min、75min三个时点所得比值的均值作为乳糖消化指数(LDI)来反应小肠乳糖酶活性。结果　乳糖吸收不良组和乳糖不耐受组两组各时点血浆总葡萄糖、1 3C 葡萄糖无显著性差异,乳糖吸收不良组的乳糖消化指数显著高于乳糖不耐受组(0 . 4 7±0 .15vs 0 . 34±0 . 14 ) ;乳糖消化指数与6h累积H2 呼出量无显著性相关关系(r=0 . 12 ,P =0 .4 6 ) ;经H2 呼气试验结果判定为乳糖酶缺乏的个体,经1 3C 乳糖 2 H 葡萄糖负荷试验分析显示小肠粘膜仍存在一定乳糖酶活性。结论　采用双标稳定同位素1 3C 乳糖2 H 葡萄糖负荷试验可以准确、灵敏地定量分析小肠粘膜乳糖酶活性,同时可以计算体内乳糖消化量。     

婴、幼儿营养性缺铁性贫血249例相关因素分析

目的探讨不同月龄婴、幼儿的营养性缺铁性贫血（nutritional iron deficiency anemia）发生情况及其相关因素。方法选择2004年1月1日至2006年12月31日在郑州市妇幼保健院儿童保健门诊接受规范4：2：1保健的1254例1～6个月（A组,n=540）、6～12个月（B组,n=360）、12～18个月（C组,n=354）儿童为研究对象（本研究遵循的程序符合郑州市妇幼保健院人体试验委员会所制定的伦理学标准,得到该委员会批准,分组征得受试对象监护人的知情同意,并与其签署临床研究知情同意书）。对其母乳喂养、辅食添加等情况进行问卷调查（自行设计）,并采用世界卫生组织（WHO）推荐的氰化高铁法测定血红蛋白（hemoglobin,Hb）含量,同时回顾性追踪母亲孕期保健资料,对采集资料进行汇总、统计学处理和分析。结果营养性缺铁性贫血总检出率为19．86％（249／1254）,其中A,B,C组儿童营养性缺铁性贫血检出率分别为26．11％（141／540）,19．17％（69／360）,11．02％（39／354）,随年龄增加,营养性缺铁性贫血发生率下降。单因素分析显示,A组婴儿中,纯母乳喂养儿（n＝414）和非纯母乳喂养儿（n＝126）缺铁性贫血检出率分别为22．46％（93／414）和38．10％（48／126）,两者比较,差异有显著意义（P〈0．05）。A组纯母乳喂养儿中,及时和过晚添加辅食儿（n=309 vs n=105）的营养性缺铁性贫血检出率分别为16．50％（51／309）,40．00％（42／105）,两者比较,差异有显著意义（P〈0．01）。母亲孕期保健资料回顾性分析结果显示,249例营养性缺铁性贫血婴、幼儿中,孕妇孕晚期缺铁性贫血为78例（31．5％）。结论婴、幼儿饮食结构不合理和母亲孕晚期缺铁性贫血,是导致婴、幼儿营养性缺铁性贫血的重要影响因素。加强围生期保健,提倡婴儿期母乳喂养的同时注意适时（4～6个月龄时）添加辅食,是减少婴儿期营养性缺铁性贫血的有效措施。     

Comparative analysis of influence of promoters and inhibitors on in vitro available iron using two methods

The investigation was undertaken with the objective of comparing two in vitro techniques, measuring dialyzable iron (method A) and measuring ionizable iron (method B), for iron bioavailability in a model system. The effect of the time of introduction of the additives on the available iron was also determined. FeSO₄ solution was used as the reference source of iron, to which a series of enhancers (ascorbic acid, citric acid, maleic acid and tartaric acid) and inhibitors (tannic acid, calcium oxalate, oxalic acid, calcium carbonate and sodium phytate) were added individually at various concentrations, and available iron was estimated. From FeSO₄ solution, 0.1% (method A) and 3.9% (method B) of iron was available. The addition of ascorbic acid, citric acid and tartaric acid increased this by 33–50%, 28–57% and 23–90%, respectively, for method A and by 15–89%, 24–78% and 24–93% for method B. Tannic acid, sodium phytate and calcium oxalate exhibited an inhibitory effect irrespective of the concentrations, while oxalic acid and calcium carbonate exhibited a dose-dependent inhibitory pattern. The iron availability analyzed by both methods showed a positive correlation with seven out of nine additives. An inverse relation was seen between the inhibitory effect of calcium carbonate and calcium oxalate and their time of introduction into the system. The overall observations showed that although absolute values varied widely, a positive correlation existed between the methods.     

Radiochromium distribution in aged rats.

Fragmentary studies suggest that tissue chromium (Cr) levels decrease with age. Regardless of the mechanism for such a decline, decreased tissue exchange with administered radiochromium (51Cr) should result. Accordingly, body retention, urinary excretion, and serum (plasma) and tissue levels of 51Cr were determined in 2-month-old male control rats and in 9-18-month-old experimental male rats 3 days after the intravenous injection of high specific activity trivalent 51Cr. The older rats retained relatively less 51Cr than the 2-month-old rats in comparison to body weight but had similar urinary excretions of 51Cr. Serum (plasma) 51Cr levels were generally higher and tissue 51Cr levels generally lower in the older rats, with the exception of spleen 51Cr content, which increased. Skeletal 51Cr content was markedly decreased, by 30-85%. These data suggest that aging alters 51Cr distribution by decreasing cellular Cr content and transport. Other mechanisms must be operative in bone since skeletal Cr is primarily extracellular.