Dietary heme iron does not prevent postgastrectomy anemia but fructooligosaccharides improve bioavailability of heme iron in rats

Iron delivery systems for controlled release of iron and enhancement of iron absorption and bioavailability

Iron deficiency is a global nutritional problem, and adding iron salts directly to food will have certain side effects on the human body. Therefore, there is growing interest in food-grade iron delivery systems. This review provides an overview of iron delivery systems, with emphasis on the controlled release of iron during gastrointestinal digestion, as well as the enhancement of iron absorption and bioavailability. Iron-bearing proteins are easily degraded by digestive enzymes and absorbed through receptor-mediated endocytosis. Instead, protein aggregates are slowly degraded in the stomach, which delays iron release and serves as a potential iron supplement. Amino acids, peptides and polysaccharides can bind iron through iron binding sites, but the formed compounds are prone to dissociation in the stomach. Moreover, peptides and polysaccharides can deliver iron by mediating the formation of ferric oxyhydroxide which is absorbed through endocytosis or bivalent transporter 1. In addition, liposomes are unstable during gastric digestion and iron is released in large quantities. Complexes formed by polysaccharides and proteins, and microcapsules formed by polysaccharides can delay the release of iron in the gastric environment and prolong iron release in the intestinal environment. This review is conducive to the development of iron functional ingredients and dietary supplements.

Systematic review of the ingestion of fructooligosaccharides on the absorption of minerals and trace elements versus control groups

BACKGROUND & AIMS

Fructooligosaccharides (FOS) are non-caloric and unconventional sugars that are not metabolized by the human body, but can be fermented by the colonic microbiota, leading to some beneficial effects on the absorption of minerals and trace elements. There is, however, a lack of research that describes the continued consumption of FOS in the diet between healthy and ill individuals and their impact. The objective of this systematic review was to evaluate the evidence behind the role of FOS in the absorption of minerals and trace elements in the human body.

METHODS

The bibliographic research covered the period from January 2000 to August 2020. Four databases were investigated. We follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA). The systematic review protocol was recorded in PROSPERO (139621). Two reviewers examined and extracted data from qualitative and quantitative studies published in the main databases, through a careful analysis. The risk of bias was assessed by four reviewers.

RESULTS

Of a total of 1494 texts, 30 complete articles composed this review. Two overarching categories represented the results: animal models and human models (randomized crossover design). Regarding human models, the results showed an improvement in minerals, especially the absorption of calcium, magnesium and iron after the ingestion of FOS, and specifically the absorption of minerals and trace elements in postmenopausal women was improved.

CONCLUSIONS

The use of FOS to improve the absorption of minerals and trace elements seems to be beneficial with evidence corroborating both in human and animal studies. However, the literature lacks articles exploring the daily dose and duration for FOS benefits, as well as long-term side effects in healthy or unhealthy subjects. Future research should focus on addressing the extent of the functional effect of this fiber and identifying the impact on overall health.

Prebiotics increase heme iron bioavailability and do not affect non-heme iron bioavailability in humans

The aim of this study was to establish the effect of a prebiotic mix on heme and non-heme iron (Fe) bioavailability in humans. To this purpose, twenty-four healthy women were randomized into one of two study groups. One group ate one yogurt per day for 12 days with a prebiotic mix (prebiotic group) and the other group received the same yogurt but without the prebiotic mix (control group). Before and after the intake period, the subjects participated in Fe absorption studies. These studies used ⁵⁵Fe and ⁵⁹Fe radioactive isotopes as markers of heme Fe and non-heme Fe, respectively, and Fe absorption was measured by the incorporation of radioactive Fe into erythrocytes. The results showed that there were no significant differences in heme and non-heme Fe bioavailability in the control group. Heme Fe bioavailability of the prebiotic group increased significantly by 56% post-prebiotic intake. There were no significant differences in non-heme Fe bioavailability in this group. We concluded that daily consumption of a prebiotic mix increases heme Fe bioavailability and does not affect non-heme iron bioavailability.

Effect of Probiotic, Prebiotic and Synbiotic Follow-up Infant Formulas on Iron Bioavailability in Rats

The effect of functional ingredients-supplemented diets on iron bioavailability and the section of the large intestine involved with this effect was investigated in rats. The diets consisted of seven powder follow-up infant formulas containing probiotics ( Bifidobacterium bifidum and Bifidobacterium longum), prebiotics (galactooligosaccharides (4'-GOS) at 1.2, 5 and 10%) or synbiotics (bifidobacteria and 4'-GOS at 1.2, 5 and 10%) that were administered to weanling rats over 30 days. Iron balancing (mineral apparent absorption and retention ratios) was carried out in three periods of 72h each. Results showed that the administration of any of the test diets increased the apparent iron absorption or retention in any of the periods, however only 10% prebiotic and synbiotic diets significantly (P<0.05) increased apparent iron absorption and retention during the three periods of mineral balancing when compared to the control group. A linear regression study demonstrated that the stimulation of iron absorption took place mainly in the colon portion of the gut, since the parameters iron absorption, crypt depth of proximal colon and pH colon content showed a multiple linear relationship (R2=0.56). We concluded that 10% prebiotic and synbiotic diets were the diets most prone to improving iron bioavailability in the colons of rats.

A Survey of Plant Iron Content-A Semi-Systematic Review

Iron is an essential mineral nutrient for all living organisms, involved in a plurality of biological processes. Its deficit is the cause of the most common form of anemia in the world: iron deficiency anemia (IDA). This paper reviews iron content in various parts of 1228 plant species and its absorption from herbal products, based on data collected from the literature in a semi-systematic manner. Five hundred genera randomly selected from the Angiosperms group, 215 genera from the Pteridophytes groups and all 95 Gymnosperm genera as listed in the Plant List version 1.1 were used as keywords together with the word "iron" in computerized searches. Iron data about additional genera returned by those searches were extracted and included in the analysis. In total, iron content values for a number of 1228 species, 5 subspecies, and 5 varieties were collected. Descriptive and inferential statistics were used to compare iron contents in various plant parts (whole plant, roots, stems, shoots, leaves, aerial parts, flowers, fruits, seeds, wood, bark, other parts) and exploratory analyses by taxonomic groups and life-forms were carried out. The absorption and potential relevance of herbal iron for iron supplementation are discussed.

Gut Function-Enhancing Properties and Metabolic Effects of Dietary Indigestible Sugars in Rodents and Rabbits

Indigestible sugars (iS) have received particular interest in food and nutrition research due to their prebiotic properties and other health benefits in humans and animals. The main aim of this review article is to summarize the current knowledge regarding digestive and health-enhancing properties of iS such as sugar alcohols, oligosacharides, and polysaccharides, in rodents and rabbits. Besides ameliorating gut health, iS ingestion also elicits laxative effects and stimulate intestinal permeability and fluid secretions, thereby shortening digesta transit time and increasing stool mass and quality. In rodents and rabbits, as hindgut fermenters, consumption of iS leads to an improved nutrient digestibility, too. Cecal fermentation of iS reduces luminal pH and extends wall tissue facilitating absorption of key dietary minerals across hindgut. The microbial fermentation of iS also enhances excessive blood nitrogen (N) flowing into the cecum to be used as N source for bacterial growth, enhancing N retention in cecotrophic animals. This review also highlights the impact of iS on improving lipid metabolism, mainly by lowering cholesterol and triglycerides levels in the blood. The paper serves as an index of the current knowledge of iS effects in rodents and rabbits and also identifies gaps of knowledge that need to be addressed by future research.

High-performance inulin and oligofructose prebiotics increase the intestinal absorption of iron in rats with iron deficiency anaemia during the growth phase

Considering the high frequency of anaemia due to Fe deficiency, it is important to evaluate the effects of prebiotics on the absorption of Fe. The aim of the present study was to evaluate the effects of high-performance (HP) inulin, oligofructose and synergy1 during recovery from anaemia in rats through the intestinal absorption of Fe, food intake, body growth, caecal pH and weight of the intestine. Wistar rats (n 47) were fed with rations of AIN93-G with no Fe to induce Fe deficiency anaemia. At 36 d of life, anaemic rats were divided into four groups: (1) the HP inulin group; (2) the synergy1 group; and (3) the oligofructose group, all with 100 g of the respective prebiotic per kg of ration; and (4) a control group, in which the prebiotic was replaced by maize starch. Then, 25 mg of elemental Fe/kg of ration was added to all rations to allow recovery from anaemia. The final values of Hb in the HP inulin, synergy1, oligofructose and control groups were, respectively: 98 (94–99); 83 (81–92); 100 (90–114); 77 (72–81) g/l, with a statistically significant difference (P ≤ 0·001) between the oligofructose and control groups and the HP inulin and control groups. The four groups had an increase in weight and body length and had similar consumption of rations. The intestinal weight and caecal pH were significantly different between the groups that consumed prebiotics and the control group. HP inulin and oligofructose increased the intestinal absorption of Fe in rats.

A ingestão de prébioticos previne a malabsorção de ferro e anemia induzidas pela gastrectomia?: Estudo experimental em ratos

RACIONAL: Ratos gastrectomizados desenvolvem anemia, e a ingestão de galactooligossacarídeo (GOS) e a polidextrose (PDX) aumenta a absorção de ferro e promove a recuperação da anemia em ratos com deficiência de ferro. OBJETIVO: Avaliar se GOS e PDX estimulam a absorção de ferro em ratos gastrectomizados e normais. MÉTODOS: Os ratos foram laparotomizadas (controle falso-operado) e parcialmente gastrectomizados (Billroth II) em grupos de 20 animais. Os animais de ambos os tratamentos foram posteriormente submetidos à dieta controle (AIN-93M) ou a mesma dieta suplementada com GOS e PDX (25 g/kg de dieta cada) durante oito semanas e divididos em quatro subgrupos: sham-operados e gastrectomizados sem GOS e PDX, sham-operados e gastrectomizados com GOS e PDX. Dois animais morreram durante o experimento. Todos os ratos gastrectomizados receberam uma injeção intramuscular de vitamina B-12 a cada duas semanas. Hematócrito (HCT) e concentração de hemoglobina (HGB) foram dosados no início e nos dias 30 e 56 dias após o início da alimentação. No último dia do estudo, o sangue total foi coletado para determinação da concentração de ferro sérico. RESULTADOS: Na dieta com GOS e PDX a excreção de ferro nas fezes foi significativamente menor do que no grupo sem prebióticos. Absorção aparente de ferro e ferro sérico foram maiores nos grupos alimentados com GOS e PDX (ambos grupos: sham operados e gastrectomizados) do que nos grupos não alimentados com GOS e PDX. O HCT e HGB foram significativamente menores nos ratos gastrectomizados que no grupo controle, entretanto, a suplementação com GOS e PDX melhorou os níveis de HGB neste grupo. CONCLUSÃO: A associação de GOS e PDX aumenta a absorção de ferro em ratos shamoperados e gastrectomizados e ainda previne a anemia pós-gastrectomia.

Ingestion of polydextrose increase the iron absorption in rats submitted to partial gastrectomy

PURPOSE: To investigate whether polydextrose stimulates iron absorption in rats submitted to partial gastrectomy and sham operated. METHODS: The rats were submitted to partial gastrectomy (Billroth II) or laparotomy (sham-operated control), in groups of 20 and 20 each respectively. The animals were fed with a control diet (AIN-93M) without polydextrose or a diet containing polydextrose (50g/Kg of diet) for eight weeks. They were divided into four subgroups: sham-operated and Billroth II gastrectomy and with or without polydextrose. Two animals died during the experiment. All rats submitted to gastrectomy received B-12 vitamin (intramuscular) each two weeks. The hematocrit and hemoglobin concentration were measured at the start and on day 30 and 56 after the beginning of the experimental period. At the end of the study, the blood was collected for determination of serum iron concentration. RESULTS: The diet with polydextrose reduced the excretion of iron. Apparent iron absorption was higher in the polydextrose fed groups than in the control group. The haematocrit and haemoglobin concentration were lower after Billroth II gastrectomy rats fed the control diet as compared to the polydextrose diet groups. CONCLUSION: Polydextrose increase iron absorption and prevents postgastrectomy anemia.

Noncitrus fruits as novel dietary environmental modifiers of iron stores in people with or without HFE gene mutations

OBJECTIVE

To investigate whether citrus fruit, noncitrus fruit, and other dietary factors act as environmental modifiers of iron status in the absence or presence of hemochromatotic HFE gene mutations.

PARTICIPANTS AND METHODS

Iron studies, HFE genotypic analyses, and dietary data from a survey conducted from March 21, 1994, through December 15, 1995, were analyzed for a group of 2232 residents (1105 men, 1127 women) aged 20 to 79 years recruited from the community electoral roll of Busselton in Western Australia. Data were analyzed by linear regression analysis and analysis of covariance.

RESULTS

Higher levels of fresh fruit intake (excluding citrus fruits and citrus juices) had a significant protective effect (P=.002) against high body iron status as gauged by ferritin levels in men, irrespective of HFE genotype. Consumption of 2 or more pieces of fruit per day on average reduced mean serum ferritin levels by 20% compared with average consumption of less than 1 piece of fruit per day. This effect was not observed in women. Consumption of citrus fruits and citrus juices had no significant effects in either sex. No protective effects were observed for tea consumption or any other dietary factors studied. Red meat and alcohol consumption correlated with high body iron stores (P<.05), consistent with previous studies, but did not interact with fruit with regard to effects on serum ferritin (P>.05).

CONCLUSION

Noncitrus fruits are environmental modifiers of iron status independent of HFE genotype. This could have important implications for the provision of evidence-based dietary advice to patients with other iron-storage disorders.

Ingestion of difructose anhydride III, a non-digestible disaccharide, prevents gastrectomy-induced iron malabsorption and anemia in rats

OBJECTIVE

Total gastrectomy produces iron malabsorption and anemia, and several non-digestible carbohydrates promote mineral absorption. In this study, we examined the effects of feeding difructose anhydride III (DFAIII), a non-digestible disaccharide, on gastrectomy-induced iron malabsorption and anemia in rats in comparison with those of feeding fructo-oligosaccharides (FOS).

METHODS

Sham-operated and totally gastrectomized male Sprague-Dawley rats were fed the control, DFAIII (30 g/kg), or FOS (30 g/kg) diet for 4 wk. Feces and tail blood were collected at 2 and 4 wk to evaluate body iron status and iron absorption.

RESULTS

Gastrectomy severely decreased net iron absorption, hemoglobin concentration, and hematocrit in the control dietary group. The decreased absorption in gastrectomized rats was restored to the sham control level by feeding the DFAIII or FOS diet. Iron absorption in sham rats was higher in the FOS and DFAIII groups than in the control group. Hemoglobin concentration and hematocrit in gastrectomized rats fed the DFAIII diet, but not the FOS diet, returned to levels comparable to the effects in sham rats fed the control diet. Feeding DFAIII increased short-chain fatty acid pools and decreased pH of cecal contents. These parameters for cecal fermentation correlated with iron absorption.

CONCLUSIONS

DFAIII feeding restores gastrectomy-induced iron malabsorption, resulting in complete prevention of iron-deficiency anemia in rats. Cecal fermentation of DFAIII may contribute to the improvement in these gastrectomy-induced defects. Feeding with low level of FOS did not fully improve postgastrectomy anemia.

Influence of Short-Chain Fructo-Oligosaccharides (sc-FOS) on Absorption of Cu, Zn, and Se in Healthy Postmenopausal Women

OBJECTIVE

This study was carried out to evaluate the effect of short-chain fructooligosaccharides (sc-FOS) on the absorption of Cu, Zn, and Se among postmenopausal women who are potential candidates to subclinical trace element deficiencies.

DESIGN

A randomized double blind cross-over study.

SETTING

This study was carried out at the Human Nutrition Research Center, Clermont-Ferrand, France.

SUBJECTS

11 postmenopausal women aged 53-70 y, not taking hormone replacement therapy were enrolled and completed the study.

INTERVENTIONS

Diets with 10 g/day sc-FOS or placebo were given for 5 weeks each in random order followed by a wash-out period of at least 3 weeks. At the end of each period, stable isotopes (3.19 mg 67Zn as ZnCl2, 2.06 mg 65Cu as CuCl2 and 52.3 microg 74Se as sodium selenite) and radiopaque pellets (as fecal excretion index) were administered during lunch. Stools were collected for the next 5-7 days. Isotopes were determined by ICP-MS (Cu and Zn) or GC-MS (Se).

RESULTS

Copper absorption was significantly enhanced (p = 0.042) by sc-FOS. No effect of sc-FOS was observed on Zn, and Se absorption.

CONCLUSION

To our knowledge, this is the first study on the influence of sc-FOS on trace element metabolism. The observed increase in copper absorption may be of interest regarding daily copper requirements in menopausal women. However, the relevance of this observation remains to be established.

Ingestion of water-soluble soybean fiber prevents gastrectomy-induced iron malabsorption, anemia and impairment of voluntary running exercise performance in rats

We examined the effects of feeding water-soluble soybean fiber (WSSF), a highly fermentable dietary fiber, on gastrectomy-induced iron malabsorption, anemia and impairment of exercise performance in rats in two separate experiments. The study was designed as a 2 x 2 factorial arrangement with operation (total gastrectomy) and diet (WSSF) under sedentary (Experiment 1) and exercised (Experiment 2) conditions. In Experiment 1, gastrectomy reduced net iron absorption, hemoglobin concentration, hematocrit and hemoglobin regeneration efficiency (P < 0.01). However, in rats fed a WSSF diet (50 g/kg diet), iron absorption and the hematological variables of the gastrectomized rats were comparable to those in the sham-operated rats, demonstrating that ingestion of WSSF promotes iron absorption and prevents anemia after gastrectomy. Feeding WSSF increased pools of organic acids and soluble iron in cecal contents and decreased the pH of the cecal contents (P < 0.001). Of the many cecal variables measured, net iron absorption in gastrectomized rats was most closely correlated (r = 0.614, P < 0.01) with the short-chain fatty acid pool in the cecum. Cecal fermentation of WSSF may contribute to improvements in gastrectomy-induced nutritional defects. In Experiment 2, we examined voluntary running exercise performance in totally gastrectomized rats fed diets with or without WSSF. Total gastrectomy severely impaired running performance (P < 0.001), and WSSF feeding largely restored the lowered performance. We conclude that feeding WSSF improves anemia and impaired voluntary running performance in totally gastrectomized rats.

The cecum and dietary short-chain fructooligosaccharides are involved in preventing postgastrectomy anemia in rats

Dietary short-chain fructooligosaccharides (Sc-FOS) stimulate absorption of calcium and magnesium in the large intestine of rats. In this study, we examined whether Sc-FOS stimulate iron absorption in the large intestine by monitoring recovery from anemia in gastrectomized rats, with or without cecectomy. The rats were divided into four groups, i.e., sham-operated (Sham), gastrectomized only (GX), cecectomized only (CX) and both gastrectomized and cecectomized (GCX). Half of the rats in each group were fed a control diet (AIN-93G) and the other half were fed a Sc-FOS-containing diet (75 g/kg diet) for 28 d. Hematocrit (Ht) and hemoglobin concentration (Hb) were measured at the start, and on d 14 and 28 after the start of feeding. On the final day of the study, total blood was collected. Gastrectomy significantly decreased Ht and Hb, but cecectomy did not influence these variables. Dietary Sc-FOS prevented the decrease in Ht and Hb significantly. In the gastrectomized rats, the effectiveness of Sc-FOS in preventing postgastrectomy anemia was significantly diminished by cecectomy. These results suggest that the effect of Sc-FOS in increasing absorption of iron in gastrectomized rats takes place in part in the cecum. The cecum plays an important role in the mechanism by which Sc-FOS prevent postgastrectomy anemia.