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1.
Polyphenolic compounds are known to possess many beneficial health effects, including the antioxidative activities of scavenging reactive oxygen species and chelating metals, such as iron and zinc. Tea and red wine are thought to be important sources of these compounds. However, some polyphenolic compounds can also reduce the absorption of iron, and possibly other trace metals, when included in a diet. There is very little information on the effect of dietary polyphenolic compounds on the status of trace elements other than iron. The effects of epigallocatechin-3-gallate (EGCG), green tea extract (GT), and grape seed extract (GSE) on the absorption of (65)Zn were examined and compared with their effects on (55)Fe absorption in human intestinal Caco-2 cells grown on microporous membrane inserts. The levels of EGCG, GT, and GSE used in this study were within physiological ranges and did not affect the integrity of the Caco-2 cell monolayers. GSE significantly (P < 0.05) reduced zinc transport across the cell monolayer, and the decreased zinc transport was associated with a reduction in apical zinc uptake. However, EGCG and GT did not alter zinc absorption. In contrast, the polyphenolic compounds in EGCG, GT, and GSE almost completely blocked transepithelial iron transport across the cell monolayer. The effect of GSE on zinc absorption was very different from that on iron absorption. Whereas GSE decreased zinc absorption by reducing apical zinc uptake, the polyphenolic compounds inhibited iron absorption by enhancing apical iron uptake. GSE inhibited zinc absorption similarly to that observed for phytate. Phytate significantly (P < 0.05) decreased transepithelial zinc transport by reducing apical zinc uptake. The inhibition of zinc absorption may be due to the presence of procyanidins in GSE, which bind zinc with high affinity and block the transport of zinc across the apical membrane of enterocytes. Further research on the absorption of zinc as zinc-polyphenol complexes and free zinc should provide further insight into the process of dietary zinc absorption in the presence of GSE and other bioactive dietary polyphenols. The present study suggests that some individuals should consider their zinc status if they regularly consume procyanidin-containing foods in their diet. However, further studies, especially in vivo studies, are needed to confirm these results.  相似文献   

2.
Staple foods, such as rice, can now be enriched in micronutrients through conventional breeding (i.e., biofortification) to enhance dietary intake of vulnerable populations. The objectives of this study were (1) to establish a rapid, high capacity Caco-2 cell model to determine the relative bioavailability of zinc (Zn) from samples of staple food breeding lines for potential use as a guideline for selection/breeding and (2) to determine the relative bioavailability of Zn from conventional rice varieties and one Zn-biofortified type. Polished or undermilled, parboiled rice samples were digested in vitro with pepsin and pH adjustment, and by pancreatic enzymes. Zn uptake from digested samples was measured in Caco-2 cells in culture. A previously validated rat pup model was also used to assess Zn absorption in vivo, using gastric intubation and (65)Zn labeling. Pups were killed after 6 h, and radioactivity in tissues and in small intestine perfusate and cecum-colon contents was used to measure Zn bioavailability. A biofortified rice variety contained substantially more Zn than conventional varieties, with no change in phytate content. Absorbed Zn (μg/g rice) was significantly higher from the new variety in both the in vitro Caco-2 cell model (2.1-fold) and the rat pup model (2.0-fold). Results from the two models were highly correlated, particularly for the polished samples. Biofortification of rice with Zn results in significantly increased Zn uptake in both models. Since results from the Caco-2 cell model correlated well with those from rat pups, this cell model is likely to predict results in human populations and can be used for screening purposes.  相似文献   

3.
The report of elevated acrylamide levels in some foods raised an international health alarm, because acrylamide probably has carcinogenic, neurotoxic, and genotoxic properties. However, data on the bioavailability of acrylamide from food matrices in humans are limited. In particular, only little is known about the interactions of acrylamide with food ingredients. Using a human intestine model (Caco-2 cells), this study shows that acrylamide monomers are highly bioavailable and pass the cell monolayer via passive diffusion. Furthermore, acrylamide binds to dietary proteins such as chicken egg albumin under intestinal and cooking conditions. This binding reduces the concentration of acrylamide monomers and leads to a reduced uptake by Caco-2 cells. Hence, it is concluded that a protein-rich diet may reduce acrylamide uptake.  相似文献   

4.
The reduced iron powder has considerable potential for use as an iron fortificant because it does not change organoleptically during storage or food preparation for cereal flour, and its bioavailability is scarcely influenced by iron absorption inhibitors in foods. The objective of this article is to study the effects of ascorbic acid, phytic acid, and pH on iron uptake from reduced iron powder (43 microm) and FeSO 4, and to compare iron bioavailability of reduced iron powders among four selected granularity levels. The cell ferritin formation is used as a marker of iron uptake. Obviously, iron uptake of reduced iron powder is increased with decreasing of powder granularity and is much lower than FeSO 4 when the size is above 43 microm, but significantly higher at 40-60 nm. In the presence of ascorbic acid or phytic acid, Caco-2 cell iron absorption from reduced iron powder (43 microm) is significantly higher than that from FeSO 4. And iron uptake of Caco-2 cells is decreased with increasing of pH from 5.5 to 7.5. Moreover, the decrease trend is more obvious for reduced iron powder than for FeSO 4. Our results indicated that iron bioavailability of reduced iron powder by intestinal enterocytes is similar to that of iron salts, and reduced iron powder is more excellent than FeSO 4 as food fortificant, especially at ultramicroscopic granularity.  相似文献   

5.
The bioavailability of iron from fortified fruit beverages was estimated by an in vitro system including enzymatic digestion, iron uptake by Caco-2 cells, and ferritin formation determined via an enzyme immunoassay (ELISA). Thus, the aim of the present study was to assess iron bioavailability as influenced by the presence of known dietary promoter and inhibitory factors in fortified fruit beverages containing iron and/or zinc and/or skimmed milk. No negative effect ( p > 0.05) derived from micronutrient interaction can be ascribed to zinc supplementation on iron availability. Besides, the presence of caseinophosphopeptides derived from casein hydrolysis during digestion may confer enhancing effects on iron absorption in samples with milk added with respect to nonadded samples ( p < 0.05). Therefore, from a nutritional point of view, individuals in need of optimal iron absorption may choose dairy samples to ensure optimal iron bioavailability.  相似文献   

6.
Our aim was to estimate the bioavailability of calcium, iron, and zinc from infant formulas using a model that includes in vitro digestion and a Caco-2 cell culture to estimate the uptake. The cell culture conditions were selected, and uptake assays were carried out first with calcium, iron, and zinc standard solutions, and then with the soluble fraction of enzymatic digests of an adapted milk-based and a soy-based infant formula. It was not possible to measure the uptake of calcium, iron, and zinc from standard solutions added to the cell cultures in amounts similar to those present in infant formula digests with our method. The fact that it was, however, possible in the case of enzymatic digests suggests the presence of components in the digests that enhance mineral uptake. When mineral uptakes were expressed as percentages of the mineral present, statistically significant differences were found in the case of calcium between the uptake from the milk- and the soy-based formulas. For iron and zinc no such differences were observed.  相似文献   

7.
Calcium solubility, dialysability, and transport and uptake (retention + transport) by Caco-2 cells as indicators of calcium bioavailability have been estimated in the in vitro gastrointestinal digests of milk and calcium fortified milk. A significant linear correlation (p < 0.05) was obtained between calcium uptake and the amount of soluble calcium added to the cells, and also between percentage calcium uptake and the calcium measured in the analyzed samples. The solubility, dialysis, transport, and uptake values are higher (p < 0.05) for calcium fortified milks than for nonfortified milks; that is, calcium fortification increases not only calcium content but also its bioavailability. An inhibitory effect of calcium from fortified milks upon iron absorption was found. The observed effect of calcium from fortified milks upon zinc bioavailability depends on the in vitro method used, zinc solubility and dialysis decrease in calcium fortified milks, and percentage zinc uptake remains unchanged.  相似文献   

8.
Iron chelates, namely, ferrous bisglycinate and ferric EDTA, are promising alternatives to iron salts for food fortification. The objectives of this study were to compare iron uptake from radiolabeled ferrous sulfate, ferrous ascorbate, ferrous bisglycinate, ferric chloride, ferric citrate, and ferric EDTA by Caco-2 cells with different iron status and in the presence of divalent metal cations. Iron-loaded Caco-2 cells, with reduced DMT-1 and elevated HFE mRNA levels, down-regulated uptake from ferrous ascorbate and bisglycinate but not from ferric compounds. Nevertheless, iron uptake from all compounds was markedly inhibited in the presence of 100-fold molar excess of Co2+ and Mn2+ cations, with ferrous compounds showing a greater percent reduction. Our results suggest that ferrous iron is the predominant form of iron taken up by intestinal epithelial cells and the DMT-1 pathway is the major pathway for uptake. Iron uptake from chelates appears to follow the same pathway as uptake from salts.  相似文献   

9.
The objective of this study was to document the effects of phytic acid, tannic acid, and zinc on iron uptake in an in vitro digestion/Caco-2 cell culture model. The effects of phytic acid and tannic acid on iron uptake were measured at increasing molar ratios of FeCl3 to phytic acid or tannic acid. Maximal inhibition of iron uptake by phytic acid occurred at a 1:10 ratio of Fe to phytic acid. Dialyzable Fe decreased with a low Fe to phytic acid ratio but increased with Fe:phytic acid ratios greater than 1:3 indicating that more iron was soluble at higher phytic acid levels but less available. As in human studies, heme iron was less inhibited by phytic acid than nonheme iron. Tannic acid was a more potent inhibitor of nonheme iron uptake, as maximal inhibition (97.5%) of iron uptake occurred at a ratio of 1:1 or less. The addition of ZnCl2 to the digest at ratios of 1:0.5 and 1:1 decreased iron uptake by 57 and 80%, respectively. Overall, the results agree qualitatively with studies in humans and demonstrate the relative effects of these compounds on iron uptake in this model system. This study provides key information for determining iron availability under more complex meal conditions.  相似文献   

10.
Iron deficiency, one of the most important nutritional problems in the world, can be caused not only by foods deficient in iron but also by poor availability of dietary iron. Iron food fortification in combination with highly available iron from supplements could effectively reduce this deficiency. The aim of this study was to examine the iron availability from iron-fortified spirulina. We have used an in vitro digestion/Caco-2 cell culture system to measure iron spirulina availability and made a comparison with those of beef, yeast, wheat floor, and iron sulfate plus ascorbic acid as a reference. Iron availability was assessed by ferritin formation in Caco-2 cells exposed to digests containing the same amount of iron. Our results demonstrate a 27% higher ferritin formation from beef and spirulina digests than from digests of yeast and wheat flour. When iron availability was expressed per microgram of iron used in each digest, a 6.5-fold increase appeared using spirulina digest in comparison with meat. In view of this observed high iron availability from spirulina, we conclude that spirulina could represent an adequate source of iron.  相似文献   

11.
A total of 60 food samples commonly consumed in China were analyzed for phytate using the anion-exchange method and for calcium, iron, and zinc using atomic absorption spectrophotometry. The foods analyzed included those based on cereal grains and soybean. Phytate contents expressed on a wet weight basis ranged from 0 for foods made from starches to 1878 mg/100 g for dried stick-shaped soybean milk film. The calcium contents were between 2.08 mg/100 g for ground corn and 760.67 mg/100 g for diced fried soybean curd. The lowest values of iron and zinc were 0.04 mg/100 g for Panjin pearl rice cooked with discarding extra water and 0.08 mg/100 g for potato and bean starches, while the highest values of iron and zinc were observed in dried stick-shaped soybean milk film. Although many foods were relatively rich in calcium, zinc, and iron, many also contained a higher level of phytate. Of the 60 food samples, 34 foods had a phytate/calcium molar ratio >0.24, 53 foods had a phytate/iron molar ratio >1, 31 foods had a phytate/zinc molar ratio >15, and only 7 foods had a phytate x calcium/zinc >200. Phytate in foods impair the bioavailability of calcium, iron, and zinc, which to some extent depends upon food processing and cooking methods.  相似文献   

12.
Lactic acid (LA) has been proposed to be an enhancer for dietary iron absorption, but contradictory results have also been reported. In the present study, fully differentiated Caco-2 cell monolayers were used to evaluate the effects of LA (1-50 mmol/L) on the cellular retention and transepithelial transport of soluble non-heme iron (as ferric nitrilotriacetate). Our data revealed a linear decline in Fe(III) retention with respect to the concentration of LA added. In the presence of 50 mmol/L LA, retention of Fe(III) and Fe(II) decreased 57% and 58%, respectively. In contrast, transfer of Fe(III) across the cell monolayer was doubled, while Fe(II) transfer across the cell monolayer decreased 35%. We conclude that LA reduces cellular retention and transepithelial transport of Fe(II) by Caco-2 cells in a dose-dependent manner. However, while LA also reduces retention of Fe(III) by Caco-2 cells, the transfer of Fe(III) across cell monolayers is enhanced, possibly due to effects on paracellular transport.  相似文献   

13.
本试验探讨鸡血细胞和血浆蛋白在体外对锌-65摄取量作为评定鸡体锌营养状况指标的可行性。试验结果表明,血细胞和血浆蛋白在体外对锌65摄取随饲粮中锌水平提高而下降,二者分别与饲粮中锌水平呈负相关(r=-0.684,-0.315);而锌-65摄取量随饲粮中钙水平提高而增加。与评定鸡体锌营养状况常用指标比较,血细胞在体外对锌-65的摄取作为反映饲粮中含锌状况的指标有较好的灵敏度,且不受血浆中营养成分变化的影响;而血浆蛋白对锌-65摄取灵敏度较差。  相似文献   

14.
Adequate bioavailable Fe intake is essential for optimal growth and intellectual development of infants and children. Fruit juices are nutritious and popular drinks for infants and children and are known to contain Fe uptake inhibitors (e.g., polyphenolic compounds) and a dominant promoter, ascorbic acid. Ascorbic acid is naturally present in fruit juices and is added during processing to almost all juices found in supermarkets. With these facts taken into account, an in vitro digestion/Caco-2 cell culture model was developed to compare the effects of apple, pear, white grape, red grape, prune, grapefruir, and orange juices on iron bioavailability. In two series of experiments, juices from a local supermarket were combined with FeCl(3) or commercial infant cereal fortified with elemental iron and subject to simulated gastric and intestinal digestion. Caco-2 cell ferritin formation in response to exposure to the digests served as the measure of Fe uptake. The pear, apple, grapefruit, orange, and white grape juice significantly increased Fe bioavailability from FeCl(3). For the infant cereal studies, the apple, orange, pear, and white grape juices increased the Fe bioavailability of the infant cereal. In contrast, the red grape juice and prune juice had profound inhibitory effects on iron bioavailability. These inhibitory effects were likely due to high levels of polyphenolic compounds that bind and thereby prevent absorption of soluble Fe. These inhibitory compounds appeared to counteract the promotional effects of ascorbic acid as they were in considerable molar excess relative to ascorbic acid and Fe in the digest. From a nutritional standpoint, the results suggest that individuals in need of optimal Fe absorption should avoid red grape and prune juice or at least vary the types of juices consumed. Alternatively, individuals seeking to limit Fe uptake (e.g., hemochromatitics and astronauts) may be able to utilize red grape or prune juice as effective inhibitors of Fe uptake. Consumers should be aware that the compounds that inhibit Fe availability are also linked to anticancer benefits; thus, a dietary balance of the above juices may be optimal.  相似文献   

15.
The common bean ( Phaseolus vulgaris) is an important staple plant food in the diets of people of Latin America, East Africa,and other regions of the developing world. It is also a major source of dietary iron. The primary goal of this research was to use an in vitro digestion/Caco-2 model to study iron bioavailability in eight genotypes (three Mesoamerican and five Andean) that represent the diversity of grain types in this crop. Complementing this goal, we measured the distribution of both iron and phytate in different bean grain tissues (cotyledon, seed coats, and embryos). Seed coats were confirmed to be the exclusive tissue containing polyphenols. The removal of the seed coat and associated polyphenols improved Caco-2 iron bioavailability, and significant differences were observed between genotypes. The addition of ascorbate enhanced iron bioavailability and exposed additional differences in Fe availability among the genotypes. These results indicate that iron accumulation and in vitro iron bioavailability vary among bean genotypes and that polyphenols had greater inhibitory effects on Caco-2 iron bioavailability as compared to phytate.  相似文献   

16.
Sodium iron(III) ethylenediaminetetraacetate (NaFeEDTA) has considerable promise as an iron fortificant because of its high bioavailability in foods containing iron absorption inhibitors. In this study, uptakes of iron from NaFeEDTA, FeSO4, and FeCl3 by Caco-2 cells were compared in the absence or presence of ascorbic acid (AA), an iron absorption enhancer; at selected pH levels; and in the absence or presence of an iron absorption inhibitor, bathophenanthroline disulfonic acid (BPDS). Ferritin formation in the cells was used as the indicator of iron uptake. Uptake from all three Fe sources was similar in the absence of AA. Adding AA at a 5:1 molar excess as compared to Fe increased uptake by 5.4-, 5.1-, and 2.8-fold for FeSO4, FeCl3, and NaFeEDTA, respectively. The smaller effect of AA on uptake from NaFeEDTA may be related to the higher solubility of NaFeEDTA and/or the strong binding affinity of EDTA for Fe3+, which may prevent AA and duodenal cytochrome b from effectively reducing EDTA-bound Fe. Uptake was inversely related to the pH of the media over a range of 5.8-7.2. Because uptake by DMT-1 is proton-coupled, the inverse relationship between pH and Fe uptake in all three iron sources suggests that they all follow the DMT-1 pathway into the cell. Adding BPDS to the media inhibited uptake from all three iron compounds equally. Because BPDS binds Fe2+ but not Fe3+ and because only Fe2+ is transported by DMT-1, the finding that BPDS inhibited uptake from NaFeEDTA suggests that at least some iron dissociates from EDTA and is reduced just as simple inorganic iron at the brush border membrane of the enterocyte. Taken together, these results suggest that uptake of iron from NaFeEDTA by intestinal enterocytes is regulated similarly to uptake from iron salts.  相似文献   

17.
OBJECTIVE: To assess the prevalence of zinc inadequacy based on dietary intakes and plasma zinc concentrations and, simultaneously, the prevalence of inadequate intakes of energy, protein, calcium and iron. DESIGN: A cross-sectional study of a convenience sample of subsistence farming households in Sidama, Southern Ethiopia. SUBJECTS: Dietary intakes were calculated from 1-day weighed food records and 40 repeats from 99 pregnant women in the third trimester using analysed values of major staple foods for zinc, iron, calcium and phytate. The distribution of observed intakes was adjusted for usual intakes and the prevalence of inadequacy estimated using the estimated average requirement (EAR) cutpoint method. Prevalence of inadequacy for zinc, protein and iron intakes were compared with those based on biochemical measures. RESULTS: Prevalence of zinc inadequacy was very high: 99% for US FNB EAR and 100% for IZiNCG EAR compared to 72% based on low plasma zinc concentrations. Corresponding prevalence estimates for iron were much lower: 4% for inadequate intakes based on US FNB EAR vs. 8.7% for iron deficiency anaemia (haemoglobin < 110 g l-1; ferritin < 12 microg l-1) and 32.3% for low storage iron. Prevalence of inadequacy for protein was 100% for adjusted intakes and 91% for serum albumin < 32 g l-1. For calcium, 74% were at risk for inadequate intakes. CONCLUSION: The high prevalence of inadequate intakes of zinc and protein was reasonably consistent with those based on biochemical measures. Such dietary deficits could be overcome by regular consumption of cellular animal protein. In contrast, both dietary and biochemical measures of iron inadequacy were low.  相似文献   

18.
The effects of the heat treatment of casein in the presence of glucose-fructose on Zn bioavailability were studied. Changes in Zn speciation were compared after in vitro digestion of heated (HC) and unheated mixture (C) alone and as part of the diet. The uptake and transport of digested soluble Zn was investigated in Caco-2 cells grown in bicameral chambers; balance studies were done in rats fed diets containing the different samples. After in vitro digestion, the precipitated Zn was significantly higher in HC than in C. In assays with Caco-2 cells, the amount of Zn transferred from the apical to the basolateral chamber was significantly greater when the culture medium contained raw or heated casein. However, because a larger proportion of Zn was precipitated by in vitro digestion, Zn utilization was less efficient in the presence of casein. In biological experiments, food efficiency of the heated casein-glucose-fructose diet was lower, and feeding this diet increased the urinary Zn excretion and lowered Zn absorption and retention. The effects of browning products generated during food processing should be taken into account, especially in diets containing marginally adequate levels of Zn, to prevent possible deficiency.  相似文献   

19.
It has previously been suggested that organic acids enhance iron absorption. We have studied the effect of nine organic acids on the absorption of Fe(II) and Fe(III) in the human epithelial cell line Caco-2. The effect obtained was dose-dependent, and the greatest increase (43-fold) was observed for tartaric acid (4 mmol/L) on Fe(III) (10 micromol/L). Tartaric, malic, succinic, and fumaric acids enhanced Fe(II) and Fe(III) uptake. Citric and oxalic acid, on the other hand, inhibited Fe(II) uptake but enhanced Fe(III) uptake. Propionic and acetic acid increased the Fe(II) uptake, but had no effect on Fe(III) uptake. Our results show a correlation between absorption pattern and chemical structure; e.g. hydroxyl groups, in addition to carboxyls, were connected with a positive influence. The results may be important for elucidating factors affecting iron bioavailability in the small intestine and for the development of foods with improved iron bioavailability.  相似文献   

20.
Extrinsic and intrinsic iron and zinc labels were used to test iron and zinc absorption from two bean (Phaseolus vulgaris) genotypes, containing normal (common beans, CB) or higher (HFeZnB) iron and zinc concentrations, fed in single meals to young women with low iron reserves. The women were divided into two groups, with one receiving a CB test meal (n = 12) and the other, an HFeZnB test meal (n = 11). The beans were intrinsically labeled hydroponically with (55)Fe (CB and HFeZnB) and with (70)Zn (HFeZnB). Concentrations of zinc and iron were 98 and 65% higher, respectively, in HFeZnB as compared to CB, but phytic acid contents were similar. Extrinsic labels were (59)Fe (CB and HFeZnB), (67)Zn (CB), and (68)Zn (HFeZnB). Iron and zinc percent absorption levels were calculated from radio-iron activity in red blood cells and from urinary excretion of zinc isotopes. Intrinsic and extrinsic iron absorption measures were highly correlated (R (2) = 0.986) (average extrinsic/intrinsic ratio was 1.00). Iron absorption was low (geometric mean < 2%) in both bean types, and total iron absorbed was not different between types. Intrinsic zinc absorption from the HFeZn beans was higher than extrinsic absorption (15.2% vs 13.4%, p < 0.05) (average extrinsic/intrinsic was 0.90). The correlation between intrinsic and extrinsic zinc measures was not as high as that for iron (R (2) = 0.719). Percent zinc absorption levels were similar in both bean types, but total extrinsic zinc absorbed was 90% higher (p < 0.05) from the HFeZnB meal. Thus, the less expensive and time-consuming extrinsic labeling may be used to screen various varieties of beans for iron bioavailability in humans, but it underestimates zinc absorption by approximately 10%. Selective breeding for high-zinc bean genotypes may improve zinc status. However, high-iron genotypes appear to have little effect on iron status when fed alone in single meals to women with low iron reserves.  相似文献   

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