Effect of Heat Treatment on Meat Enhancement of Dietary Iron Bioavailability of Meat/Ferrous Sulfate and Meat/Hemoglobin Mixtures Fed to Anemic Rats

The effect of autoclaving on meat enhancement of dietary iron bioavailability was studied. Meat was mixed with FeSO₄ or hemoglobin to obtain ratios of iron from meat to iron from FeSO₄ or hemoglobin of 100:0, 75:25, 50:50, 25:75, and 0:100. One-half of each mixture (except meat:FeSO₄ mixture 0:100) was autoclaved for 90 min at 15 psi. The meat mixtures were lyophilized and formulated into diets to provide approximately 35 mg Fe/kg. Hemoglobin regeneration efficiency (HRE) was determined as the percent iron gained as hemoglobin relative to the iron consumed. Heat increased the HREs of meat/hemoglobin mixtures and of hemoglobin. Heat did not affect the HRE of meat or meat/ferrous sulfate mixtures. Meat did not significantly enhance the bioavailability of total dietary iron.     

Iron Availability from Soy, Meat and Soy/Meat Samples in Anemic Rats With and Without Prevention of Coprophagy

The biological availability of iron from samples of soy proteins (nontextured, extruded and spun), meat (chicken and beef) and spun soy/meat combination products was compared to ferrous sulfate using a hemoglobin regeneration bioassay. Compared to ferrous sulfate (55%) iron availability from the various soy proteins ranged from 29-57%, for the meat samples 32-39% and for soy/meat combination products 61-92%. There was no significant improvement in iron availability by fortification with ferrous sulfate or ascorbic acid. Prevention of coprophagy in the anemic rats during the bioassay using aluminum anal cups produced varying degrees of reduction in iron availability for various samples and this effect clearly needs further investigation.     

Bioavailability of iron in goat milk compared with cow milk fed to anemic rats

Bioavailabilities of iron from dehydrated whole and skim goat milk were investigated using iron-deficient rats. Hemoglobin regeneration efficiencies were determined as the percent conversion of dietary iron into hemoglobin. The respective hemoglobin regeneration efficiencies for groups fed whole goat milk, whole cow milk, skim goat milk, and skim cow milk were 50.6, 13.1, 26.0, and 13.0%, indicating that iron bioavailability of goat milk was greater than cow milk. However, rats fed each milk had negative net increases in hemoglobin concentrations, implying that the iron contents of each milk were not adequate. For animals consuming whole goat milk supplemented with ferrous sulfate, the slope relating hemoglobin iron gained versus iron intake was .95. Respective bioavailabilities relative to ferrous sulfate were 54, 14, 28, and 14% for the four sources of milk. Iron bioavailability of goat milk is superior to cow milk when fed to anemic rats.     

Extrusion and iron bioavailability in chickpea (Cicer arietinum L.)

The effect of extrusion cooking (14% moisture and 130°C processing temperature) and of home-cooking on chickpea iron bioavailability was studied by the hemoglobin regeneration method in anemic rats. The iron pool was calculated from hemoglobin concentration and animal weight, and iron bioavailability from the relationship between iron pool gain (Δ pool) and mg of ingested iron. Iron bioavailability relative to ferrous sulfate was calculated by the following equation: Y=63.989 e^−0.0458X [Y= % absorbed; X=ingested Fe (mg)] on the basis of the results of control groups. The results showed that there was no significant difference between groups (extruded and cooked) in terms of mean percentage of iron bioavailability relative to Fe₂SO₄. We conclude that chickpea is a good source of iron and extrusion cooking is a process comparable to home-cooking in terms of iron bioavailability.     

Relative Bioavailability of Dietary Iron from Three Processed Soy Products

The relative bioavailability of iron from soy flour (SF), freeze-dried soy beverage (SB) and soy concentrate (SC) was determined utilizing a hemoglobin repletion bioassay. Weanling male rats were fed a low iron depletion diet (3.5 ppm Fe) for 4 wk. For the next 2 wk groups of rats were fed repletion diets containing 0, 6, 12, or 18 ppm added iron from ferrous sulfate, SF, SB, or SC. Slope ratio analysis revealed that the relative iron bioavailabilities from SC (92%) and SF (81%) were not different from the reference standard, ferrous sulfate added to a casein-based diet, whereas that from SB (66%) was significantly less (P<0.01) than the inorganic source of iron. Analysis of results at individual iron levels suggested an iron bioavailability of SC>SF>SB.     

蛋氨酸螯合铁对大鼠肝脏物质代谢相关基因表达的影响

研究缺铁日粮中补充蛋氨酸螯合铁与硫酸亚铁对大鼠铁利用及肝基因表达的影响。20只SD断奶大鼠,建立缺铁大鼠模型,然后均分成两组,分别饲喂加入等量铁(35mg/kg)的蛋氨酸螯合铁和硫酸亚铁日粮,补铁后4、7d后测定体重、血红蛋白,组织器官铁含量及血清总铁结合力;并提取大鼠肝组织总RNA,用Afymetrix基因芯片进行基因表达分析,研究硫酸亚铁与蛋氨酸螯合铁对缺铁大鼠物质代谢基因表达的差异。结果表明,蛋氨酸螯合铁组大鼠增重明显高于硫酸亚铁组,血红蛋白、总铁结合力含量有升高趋势。与硫酸亚铁组比较,蛋氨酸螯合铁组肝组织珠蛋白与转铁蛋白合成相关基因,以及胆固醇合成,脂肪代谢、ATP合成相关基因明显上调。补充蛋氨酸螯合铁动物铁代谢和物质代谢存在显著差异。     

Bioavailability of Iron in Iron-Fortified Fluid Milk

The bioavailability of iron in pasteurized and homogenized cow's milk was determined by the hemoglobin depletion-repletion technique using rats. A water soluble citrate phosphate iron complex (iron, 16.67%) was used to fortify milk (iron, 38 ppm). Results showed that iron in milk was as well available as that in ferrous sulfate (99% vs 100%); the same was true when the iron complex was tested as such (not added to milk). Thus, milk or milk components appear not to adversely affect the bioavailability of added iron under the conditions of this experiment.     

Iron bioavailability in iron-fortified cereal foods: The contribution of in vitro studies

Iron deficiency anemia is the most common nutritional deficiency in humans. Not all dietary ingested iron, heme or nonheme, will be available to absorption and negative imbalance between iron requirements and absorption leads to iron deficiency and/or anemia. The recommended iron values usually are based on the genetic and on diet iron-bioavailability, which can be considered as the principal factor that change among the cultures and influences the distinct levels of recommendation among countries. Dietary changes present practical limitations due to be difficult to change food habits. The iron food fortification is considered more cost effective and economically more attractive than iron supplementation. There are many iron compounds available to be used in iron fortification. Cereals represent a target food group to iron fortification programs due to high consumption and the in vitro studies can be useful to estimate the relative iron bioavailability in large number of products in short time and with a low cost. Wheat flour baked into bread or not was the main product tested in in vitro bioavailability studies and ferrous sulfate was the principal iron compound used in the fortification studies. However, iron bioavailability from ferrous sulfate is lower than from other compounds, such FeNaEDTA or ferric pyrophosphate. The variables level of fortification, storage, level of extraction, baking and also the association or not with other chemical compound seems to influence the results obtained.     

苏氨酸铁对缺铁性贫血大鼠铁营养状况的改善

目的:探讨苏氨酸铁(Thr-Fe)对缺铁性贫血(IDA)大鼠铁营养状况的改善作用。方法:以低铁饲料饲喂雄性初断乳斯泼累格·多雷(SD)大鼠建立IDA模型,设置3个不同Thr-Fe剂量组和阳性对照组、低铁对照组、空白对照组,每组6只,每天灌胃1次,连续给药21 d,Thr-Fe剂量组分别给予8、16、32 mg/kg·bw的Thr-Fe,阳性对照组给予32 mg/kg·bw硫酸亚铁。结果:较低铁对照组,Thr-Fe高剂量组大鼠体重及血红蛋白、血清铁蛋白等血液指标显著提高(p<0.01),血清转铁蛋白(p<0.01)和总铁结合力(p<0.05)显著降低,各Thr-Fe剂量组大鼠游离原卟啉显著降低(p<0.01)。Thr-Fe高剂量组IDA大鼠各项指标改善优于阳性对照组。结论:低铁膳食补充Thr-Fe可以改善IDA大鼠的铁营养状况,提高功能铁及贮存铁含量,促进机体铁转运。Thr-Fe对IDA大鼠体重及血红蛋白等的影响呈剂量相关性,Thr-Fe对IDA大鼠铁营养状况的改善效果优于硫酸亚铁。     

Bioavailability of Zinc and Iron from Mature Winged Bean Seed Flour

The relative bioavailability of zinc and iron from mature winged bean (Psophocarpus tetragonolobus) flour was determined utilizing standard rat bioassay procedures. Weight gain of rats after 21 days and total bone (tibia) zinc resulting from zinc addition to the standard diet as zinc carbonate or from zinc endogenous to winged bean flour were compared. The relative bioavailability of winged bean zinc was calculated to be 85% (P < 0.05) and 93% (N.S.) when weight gain and log tibia zinc were the criteria of evaluation. The results of the hemoglobin repletion assay indicated that iron from winged bean was 89% (N.S.) as bioavailable iron from ferrous sulfate.     

Iron Bioavailability from Common Raisin-containing Foods Assessed with an In Vitro Digestion/Caco-2 Cell Culture Model: Effects of Raisins

The effects of raisins on iron bioavailability from wheat bran cereal, bread, rice pudding, and granola bars were studied. Iron bioavailability was assessed with an in vitro digestion/Caco‐2 cell culture model. Raisins reduced iron bioavailability from all foods except granola bars. Raisins also reduced iron bioavailability from samples of wheat bran cereal and bread fortified with elemental iron or ferrous sulfate, but this inhibitory effect was less pronounced in samples fortified with sodium iron ethylenediaminetetraacetate (NaFeEDTA). Iron bioavailability was markedly higher for samples fortified with NaFeEDTA, suggesting that iron in the form of NaFeEDTA is more bioavailable than elemental iron or ferrous sulfate in raisin‐containing foods.     

Influence of high dietary iron as ferrous carbonate and ferrous sulfate on iron metabolism in young calves

Twelve intact male Holstein calves averaging 90 kg and 12 wk of age were fed one of three dietary treatments for 28 d. The diets were A) control, B) control plus 1000 ppm iron as ferrous carbonate, and C) control plus 1000 ppm iron as ferrous sulfate monohydrate. Calves were dosed orally on d 15 of the treatment period with 1 mCi of iron-59. Neither source of added iron had a significant effect on weight gains, feed consumption, hemoglobin, packed cell volume, serum total iron, serum total iron-binding capacity, unbound iron-binding capacity, serum copper, tissue copper, fecal dry matter, or a consistent effect on fecal pH. The ferrous carbonate had no significant effect on stable zinc or stable iron in any tissue studied. Calves fed ferrous sulfate had higher average stable iron in most tissues and significantly more in the small intestine. Tissue zinc was lower in spleen and pancreas of ferrous sulfate-fed calves. Both sources of added iron sharply reduced iron-59 in serum, whole blood, and body tissues. The reduction was substantially greater in calves fed the ferrous sulfate iron. Iron in ferrous sulfate had a higher biological availability than that in the ferrous carbonate; however, bioavailability of the ferrous carbonate iron appeared to be substantial and considerably more than that noted in previous studies in which a different source of ferrous carbonate was used. The maximum safe level of dietary iron is materially influenced by the source of iron with a higher tolerance indicated for ferrous carbonated than ferrous sulfate monohydrate.     

Heating and the Distribution of Total and Heme Iron Between Meat and Broth

The effect of heat on movement of total and heme iron from meat to broth was investigated. Total iron by a wet ash method was nearly identical to the sum of heme iron plus nonheme iron. The total amount of nonheme iron increased with cooking temperature (r = 0.98), as did the amount of nonheme iron in the broth (r = 0.93). Leaching of heme pigments into the broth was greatest at 60°C. Boiling (97°C) rapidly coagulated the meat pigments and minimized the leaching of heme pigments into the broth. More total iron (85.3%) was retained in boiled (97°C) meat than in meat heated 1 hr at 60°C (81.6%), 77°C (78.2%) or autoclaved (77.5%).     

Bioavailability of iron-milk-protein complexes and fortified cheddar cheese

Iron fortification is used to increase dietary iron intake. Dairy products are widely consumed but contain almost no iron. Cheddar cheese was fortified with ferric chloride or iron-casein, ferripolyphosphate-whey protein, and iron-whey protein complexes. Hemoglobin regeneration efficiency was determined to evaluate iron bioavailability. Maximal and basal iron bioavailabilities were measured in anemic weanling rats fed low iron diets (about 22 mg iron/kg) and normal adult rats fed high iron diets (about 145 mg iron/kg) of iron density (32 mg iron/1000 kcal) found in some high iron human diets. Maximal iron bioavailabilities for ferric chloride or iron-casein, ferripolyphosphate-whey protein, and iron-whey protein complexes were 85, 71, 73, and 72%, respectively, and for the respective iron-fortified cheeses they were 75, 66, 74, and 67%. Differences were not significant in maximal iron bioavailabilities among iron sources and between fortified cheeses and fortification iron sources. Basal iron bioavailabilities for 10-d feeding of the respective fortification iron sources were 5, 8, 6 and 7%, respectively, and 4, 4, 3, and 3% for 14 d feeding; the differences among the iron sources were not significant. Maximal and basal iron bioavailabilities of ferrous sulfate were 85 and 5%, respectively. Practical implications of these observations are discussed.     

Bioavailability of Iron in Green Peas, Spinach, Bran Cereal, and Cornmeal fed to Anemic Rats

Bioavailability of iron from green peas, spinach, bran cereal and cornmeal was evaluated by hemoglobin regeneration efficiency in the anemic rat. By analysis these respective food items contained 85, 163, 55 and 35 mg of iron per kg of dry weight. Iron from ferrous sulfate, peas, spinach, bran cereal and cornmeal was converted to hemoglobin iron with respective efficiencies of 67, 64, 34, 53 and 39 percent. Based on these bioavailabilities, peas, spinach, bran cereal, and cornmeal provide 14, 19, 12, and 3 mg of available iron per 1000 kcal. Plant foods can make significant contribu tions of available iron in the diet.     

Effect of processing on iron bioavailability of extruded bovine lung

The iron bioavailability of extruded and non-extruded lung products was compared with that of ferrous sulfate by the haemoglobin regeneration method. Extrusion was performed in a laboratory extruder (L/D 20:1) at several processing temperatures and moisture contents of the feed (115–160 °C; 16–30% moisture) with screw (4:1 compression ratio) speed fixed at 200 rpm. These conditions included the optimum observed for lung texturization. Bioavailability of iron was determined as efficiency of haemoglobin regeneration in rats fed bovine extruded lung-based diets, compared with non-extruded lung and casein standard diets. The results showed that iron bioavailability was high and comparable with ferrous sulfate standard, irrespective of the extrusion conditions adopted. These results showed that extruded lung can be used as a good iron source, even if processed in conditions deleterious for other nutrients.     

Preparation,characterization, bioavailability in vitro and in vivo of tea polysaccharides–iron complex

The task of this study was to prepare a complex of tea polysaccharides (TPS) with ferric iron and research its bioavailability in vitro and in vivo. Optimum condition for preparing tea polysaccharides–iron complex (TPIC) was as follows: TPS and FeCl₃ with a weight ratio of 1:2.4, reacted in a water bath at 60 °C for 3 h, generating an iron content for TPIC of 14.60 %. The digestion in vitro experiment showed that availability of TPIC was sufficient. Then, iron bioavailability in vivo of TPIC was evaluated by the rat hemoglobin-repletion bioassay with ferrous sulfate (FeSO₄) as the positive control. Results indicated that at the end of 21 days’ iron regeneration phase, the values of hemoglobin (Hb) concentration, free erythrocyte protoporphyrin (FEP), serum iron (SI) concentration, and mean cell hemoglobin (MCHC) of rats supplemented with FeSO₄ and TPIC increased quickly to those of normal ones. If the bioavailability of FeSO₄ was given 100 % with Hb concentration, SI concentration and MCHC as the evaluation index, respectively, bioavailability of TPIC were in the range of 101.85–116 %. These results demonstrate that TPIC is a good iron supplement source for increasing uptake and bioavailability in the body.     

鸡蛋卵转铁蛋白螯合铁及其对大鼠贫血模型的影响

将从鸡蛋中分离纯化的卵转铁蛋白与FeCl3结合,研究其在不同铁离子浓度、pH值、NaHCO3和温度条件下与铁离子的结合能力。通过色度仪、红外光谱仪、粒径分析仪、扫描电镜等仪器研究冷冻和喷雾干燥对螯合铁卵转铁蛋白理化性质的影响。在0.4 mmol/L FeCl3,120 mmol/L NaHCO3,pH 8.0,温度低于60℃时,卵转铁蛋白铁结合能力为91.5%,结合的铁含量为1.28μg/g。冷冻和喷雾干燥对螯合铁卵转铁蛋白的色度、粒径分布、完全溶解时间存在极显著的差异,而在水分活度和化学键结构方面无明显差异。建立缺铁大鼠模型,考察30 d内卵转铁蛋白对大鼠贫血的改善作用,结果表明:冷冻和喷雾干燥处理的螯合铁卵转铁蛋白对贫血大鼠体重和脏器指数升高有显著作用;对血常规中的红细胞计数、血红蛋白浓度、血细胞压积、红细胞平均体积均有正向促进作用(P<0.01),能够显著增加大鼠血液中血清铁含量,提高血清铁蛋白含量,降低血清总铁结合力(P<0.05),部分指标优于对照组硫酸亚铁。卵转铁蛋白可作为一种生物补铁剂显著改善大鼠的缺铁性贫血状况。     

Soybean Hulls as an Iron Source for Bread Enrichment

Soybean hulls, a concentrated source of iron, may have potential as a source of iron fortification in baked products. Retention of ⁵⁹Fe in rats from white bread containing intrinsically labeled soybean hulls did not differ significantly (p<0.05) from extrinsically labeled white bread fortified with bakery grade ferrous sulfate (70.4 and 63.1%, respectively). Physical and sensory evaluations of bread containing up to 5% soybean hulls did not differ from white bread in loaf volume, cross-sectional area, tenderness or overall acceptance. These results suggest that soybean hulls are a good source of available iron and may be added to bakery products without deleterious effects in baking performance and sensory acceptability.     

Effects of Meat and Selected Food Components on the Valence of Nonheme Iron during In Vitro Digestion

Our objective was to determine whether meat and other dietary factors have the capacity to reduce nonheme ferric iron to the ferrous form during digestion. Beef, selected organic acids, selected purified proteins, red blood cells, whole blood, or blood plasma was mixed with FeCl₃ and subjected to simulated gastrointestinal digestion. Ferrozine was used to monitor the formation of dialyzable Fe(II). Ascorbic acid, glutathione and cysteine produced large increases in Fe(II) while meat (raw and cooked), hemoglobin and red blood cells yielded smaller increases. Casein, plasma, bovine serum albumin and egg albumin did not affect Fe(II) formation. Our Results suggest dietary factors which enhance iron absorption in vivo promote Fe(III) reduction in the intestinal lumen.