Comprehensive insight into the alterations in the gut microbiome and the intestinal barrier as a consequence of iron deficiency anaemia

BACKGROUND

Iron deficiency is the top leading cause of anaemia, whose treatment has been shown to deteriorate gut health. However, a comprehensive analysis of the intestinal barrier and the gut microbiome during IDA have not been performed to date. This study aims to delve further into the analysis of these two aspects, which will mean a step forward minimising the negative impact of iron supplements on intestinal health.

METHODS

IDA was experimentally induced in an animal model. Shotgun sequencing was used to analyse the gut microbiome in the colonic region, while the intestinal barrier was studied through histological analyses, mRNA sequencing (RNA-Seq), qPCR and immunofluorescence. Determinations of lipopolysaccharide (LPS) and bacteria-specific immunoglobulins were performed to assess microbial translocation.

RESULTS

Microbial metabolism in the colon shifted towards an increased production of certain amino acids, short chain fatty acids and nucleotides, with Clostridium species being enriched during IDA. Structural alterations of the colonic epithelium were shown by histological analysis. RNA-Seq revealed a downregulation of extracellular matrix-associated genes and proteins and an overall underdeveloped epithelium. Increased levels of serum LPS and an increased immune response against dysbiotic bacteria support an impairment in the integrity of the gut barrier during IDA.

CONCLUSIONS

IDA negatively impacts the gut microbiome and the intestinal barrier, triggering an increased microbial translocation. This study emphasizes the deterioration of gut health during IDA and the fact that it should be addressed when treating the disease.

Fermented Goat's Milk Contributes to the Recovery of Iron Deficiency Anemia via Modulation of the Gut Microbiome

Iron deficiency anemia (IDA) is a global public health concern affecting 1.6 billion people worldwide. The administration of iron supplements during the treatment of IDA adversely affects the intestinal barrier function and the composition and functionality of the intestinal microbiome, both of which are already altered during IDA. For this reason, it is of great interest to develop nutritional strategies aimed at alleviating these gut alterations associated with IDA and its treatment. In this sense, fermented goat's milk (FGM) was studied due to its nutritional quality. Our findings showed that in anemic animals the consumption of a FGM-based diet, compared to a standard diet, had positive modulatory effects on the intestinal microbiome. FGM-based diet restored intestinal dysbiosis, the intestinal barrier functionality, and bacterial translocation, contributing to a more efficient recovery of IDA. Therefore, FGM is a useful nutritional tool to ease intestinal alterations occurring during IDA and during its treatment.

Gut microbiome-short-chain fatty acids interplay in the context of iron deficiency anaemia

PURPOSE

Anaemia is a global health concern, with iron deficiency anaemia (IDA) causing approximately 50% of cases. Affecting mostly the elderly, pregnant and adult women and children, physiopathology of IDA in relation to the gut microbiome is poorly understood. Therefore, the objective of this study is to analyse, in an animal model, the effect of IDA on the gut microbiome along the gastrointestinal tract, as well as to relate intestinal dysbiosis to changes in microbial metabolites such as short chain fatty acids (SCFA).

METHODS

IDA was experimentally induced through an iron deficient diet for a period of 40 days, with twenty weaned male Wistar rats being randomly divided into control or anaemic groups. Blood samples were collected to control haematological parameters, and so were faecal and intestinal content samples to study gut microbial communities and SCFA, using 16S rRNA sequencing and HPLC-UV respectively.

RESULTS

An intestinal dysbiosis was observed as a consequence of IDA, especially towards the distal segments of the gastrointestinal tract and the colon. An increase in SCFA was also noticed during IDA, with the major difference appearing in the colon and correlating with changes in the composition of the gut microbiome. Clostridium_sensu_stricto_1 and Clostridium_sensu_stricto_4 showed the greatest correlation with variations in butyric and propionic concentrations in the colon of anaemic animals.

CONCLUSIONS

Composition of intestinal microbial communities was affected by the generation of IDA. An enrichment in certain SCFA-producing genera and SCFA concentrations was found in the colon of anaemic animals, suggesting a trade-off mechanism against disease.

Fermented goat's milk modulates immune response during iron deficiency anemia recovery

BACKGROUND

Iron deficiency and iron overload can affect the normal functioning of the innate and adaptive immune responses. Fermented milk products may enhance immune functions, but little is known about the effect of fermented milks on modulation of the immune response during iron deficiency anemia and recovery with normal or high dietary iron intake. Eighty male Wistar rats were randomly assigned to a control group fed a standard diet or to an anemic group fed a diet deficit in iron. Control and anemic groups were fed for 30 days with diets based on a fermented goat's or cow's milk product, with normal iron content or iron overload.

RESULTS

In general, during anemia recovery lectin and alternative complement pathway activity and lactoferrin decreased, because it improves iron homeostasis, which is critically important in immune system functions. Fermented goat's milk diet enhanced immune function during iron deficiency recovery, suppressed oxidant-induced eotaxin and fractalkine expression due to the concurrent reduction of free radical production and pro-inflammatory cytokines, and decreased monocyte chemoattractant protein-1 and monocyte migration and adhesion. The increase in interferon-γ can confer immunological colonization of gut microbiota and downregulate inflammation.

CONCLUSION

Fermented goat's milk consumption enhances immune function, modifying complement pathway activity and decreasing pro-inflammatory cytokines as well as lactoferrin concentration, due to the improvement of iron homeostasis, which is critically important in the normal function of the immune system. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Role of Fermented Goat Milk on Liver Gene and Protein Profiles Related to Iron Metabolism during Anemia Recovery

Despite the crucial role of the liver as the central regulator of iron homeostasis, no studies have directly tested the modulation of liver gene and protein expression patterns during iron deficiency instauration and recovery with fermented milks. Fermented goat milk consumption improves the key proteins of intestinal iron metabolism during iron deficiency recovery, enhancing the digestive and metabolic utilization of iron. The aim of this study was to assess the influence of fermented goat or cow milk consumption on liver iron homeostasis during iron-deficiency anemia recovery with normal or iron-overload diets. Analysis included iron status biomarkers, gene and protein expression in hepatocytes. In general, fermented goat milk consumption either with normal or high iron content up-regulated liver DMT1, FPN1 and FTL1 gene expression and DMT1 and FPN1 protein expression. However, HAMP mRNA expression was lower in all groups of animals fed fermented goat milk. Additionally, hepcidin protein expression decreased in control and anemic animals fed fermented goat milk with normal iron content. In conclusion, fermented goat milk potentiates the up-regulation of key genes coding for proteins involved in iron metabolism, such as DMT1, and FPN1, FTL1 and down-regulation of HAMP, playing a key role in enhanced iron repletion during anemia recovery, inducing a physiological adaptation of the liver key genes and proteins coordinated with the fluctuation of the cellular iron levels, favoring whole-body iron homeostasis.

Fermented Goat Milk Consumption Enhances Brain Molecular Functions during Iron Deficiency Anemia Recovery

Iron deficiency anemia (IDA) is one of the most prevalent nutritional deficiencies worldwide. Iron plays critical roles in nervous system development and cognition. Despite the known detrimental consequences of IDA on cognition, available studies do not provide molecular mechanisms elucidating the role of iron in brain functions during iron deficiency and recovery with dairy components. In this study, 100 male Wistar rats were placed on a pre-experimental period of 40 days and randomly divided in two groups: a control group receiving a normal-Fe diet, (45 mg/kg), and an Fe-deficient group receiving a low-Fe diet (5 mg/kg). At day 40, 10 rats per group were sacrificed to anemia control, and 80 rats were divided into eight experimental groups fed with fermented goat or cow milk-based diets, with normal Fe content or Fe overload (450 mg/kg) for 30 days. IDA decreased most of the parameters related to brain molecular functions, namely dopamine, irisin, MAO-A, oxytocin, β-endorphin, and α-MSH, while it increased synaptophysin. These alterations result in an impairment of brain molecular functions. In general, during anemia recovery, fermented goat milk diet consumption increased dopamine, oxytocin, serotonin, synaptophysin, and α-MSH, and decreased MAO-A and MAO-B, suggesting a potential neuroprotective effect in brain functions, which could enhance brain molecular functions.

Iron Deficiency and Neuroendocrine Regulators of Basal Metabolism, Body Composition and Energy Expenditure in Rats

Although dietary iron is a determinant of iron status in animals, body fat mass has been reported to have an inverse association with iron status in human studies. The goal of this study was to determine the relationship between Fe homeostasis, body composition, energy expenditure and neuroendocrine regulators for severe Fe-deficiency anaemia. Forty male Wistar albino rats recently weaned were divided at random into two groups: the control group was fed the basal diet, AIN-93G diet (normal-Fe) and the anaemic group received a low-Fe diet for 40 days. Neuroendocrine parameters that regulate basal metabolism and appetite (thyroid hormones, ghrelin, glucose-dependent insulinotropic polypeptide (GIP), glucagon, insulin, adrenocorticotropic hormone and corticosterone), body composition, respiratory volumes, energy expenditure, haematological and biochemical were assessed. Total body fat was lower, whereas lean mass, free and total water were higher in the anemic group. O₂ consumption, CO₂ production, energy expenditure (EE) and respiratory quotient (RQ) were lower in the Fe-deficient animals. Triiodothyronine and thyroxine hormones decreased, while thyroid-stimulating hormone increased in the anemic group. Circulating levels of ghrelin were lower in the anemic group, while GIP, glucagon, insulin, corticosterone and adrenocorticotropic hormone levels were higher. Fe-deficiency impairs weight gain in the rats, with marked reductions in lean mass and body fat, indicating lower energy stores.

Protective effects of fermented goat milk on genomic stability, oxidative stress and inflammatory signalling in testis during anaemia recovery

Oxidative stress is a harmful factor for male reproductive function, and a major cause of infertility. On the other hand, fermented goat milk has positive effects on anemia recovery and mineral metabolism. This study evaluated the effect of feeding rats with fermented milks during anaemia recovery on molecular mechanisms linked to oxidative stress and inflammatory signalling in rats reproductive system. Forty male Wistar rats were placed on a pre-experimental period of 40 days (control group, receiving normal-Fe diet and Fe-deficient group, receiving low-Fe diet). Lately, rats were fed with fermented goat or cow milk-based diets during 30 days. After feeding the fermented milks, Total antioxidant status (TAS) and non-esterified fatty acids (NEFA) increased and 8-hydroxy-2’-deoxyguanosine (8-OHdG), 15-F2t-isoprostanes and thiobarbituric acid reactive substances (TBARS) decreased in testis. DNA oxidative damage in testis germ cells was lower with fermented goat milk. Fermented goat milk reduced IL-6 and TNF-α in control animals, increasing INF-γ in control and anaemic rats. NRF2 and PGC-1α protein levels increased in testis after fermented goat milk consumption in control and anaemic rats. Fermented goat milk also increased TAS and decreased oxidative damage, protecting the main testis cell bioconstituents (lipids, proteins, DNA, prostaglandins) from oxidative damage and reduced inflammatory activity, preventing injuries to testis germinal epithelium. Fermented goat milk enhanced lipolysis, fatty acids degradation and immune response, attenuating inflammatory signalling, representing a positive growth advantage for testicular cells.

Fermented goat milk consumption improves cardiovascular health during anemia recovery

BACKGROUND

Iron (Fe) plays a crucial role in several fundamental processes, including erythropoiesis, cellular metabolism, and in cardiovascular disease. The aim of this work was to contribute to a better understanding of the physiology of and recovery from Fe deficiency by studying how fermented milk consumption affects vascular biomarkers during Fe repletion.

RESULTS

The deleterious cardiovascular biomarkers cytokine-induced neutrophil chemoattractant 1, connective tissue growth factor (CTGF), interleukin-6, monocyte chemoattractant protein-1 (MCP-1), inhibitor of tissue plasminogen activator 1 total, metallopeptidase inhibitor 1 (TIMP-1), tumor necrosis factor alpha, vascular endothelial growth factor (VEGF), sE-selectin, and soluble intercellular adhesion molecule 1 (sICAM-1) decreased after fermented goat milk consumption in groups of fed animals either with normal Fe or Fe overload with respect to rats fed with fermented cow milk. The beneficial cardiovascular biomarkers caveolin-1 and adiponectin were higher in both control and anemic rats fed fermented goat milk either with normal Fe or Fe overload with respect to fermented cow milk. Anemia decreased TIMP-1 in rats fed fermented goat milk with Fe overload, whereas there was increased CTGF and MCP-1 in animals fed fermented cow milk with either normal or Fe overload. In addition, Fe overload increased VEGF.

CONCLUSION

Fermented goat milk consumption improves hematological status and promotes beneficial metabolic responses, which may attenuate cardiovascular risk factors during anemia recovery and iron overload to lessen the inflammatory response, macrophages activation and atherosclerosis development. © 2018 Society of Chemical Industry.

Fermented goat milk consumption improves iron status and evokes inflammatory signalling during anemia recovery

In spite of the crucial role of the inflammatory state under anemic conditions, to date, no studies have directly tested the modulation of cytokines during iron overload.

Changes in Adiposity and Body Composition during Anemia Recovery with Goat or Cow Fermented Milks

To date, no studies are available about adipose tissue modifications during anemia recovery; therefore, the aim of this study is to provide detailed information about adipose tissue homeostasis during anemia recovery with fermented milks. Forty male Wistar rats were placed on a pre-experimental period of 40 days, divided in two groups (normal-Fe diet and Fe-deficient diet). Then rats were fed fermented goat or cow milk-based diets with normal-Fe content during 30 days. Ghrelin and adiponectin decreased in both groups of animals fed fermented goat milk, whereas leptin and NEFA increased. UCP-1 decreased in anemic rats fed either fermented milk, and irisin greatly increased in both groups of animals fed fermented goat milk. Fermented goat milk reduces adiposity, inducing leptin elevation and ghrelin reduction. Conversely, plasma adiponectin concentrations decreased in animals fed fermented goat milk, showing an inverse correlation with NEFA, an important marker of lipid mobilization, indicating increased lipolysis. Irisin up-regulation in animals fed fermented goat milk contributes to a favorable metabolic profile and the browning of adipose tissue during anemia recovery.

Fermented goat milk improves antioxidant status and protects from oxidative damage to biomolecules during anemia recovery

BACKGROUND

Iron deficiency anemia (IDA) is one of the most common nutritional problems in the world, and it is accepted that reactive oxygen species (ROS) production is altered during IDA. The aim of this study was to assess the influence of fermented goat and cow milks on enzymatic antioxidant activities and gene expression, and their role in protecting from oxidative damage during anemia recovery.

RESULTS

After feeding the fermented milks-based diets (cow or goat), a significant elevation of some antioxidant endogenous enzymes was found, together with an increase in total antioxidant status (TAS), and a decrease in 8-hydroxy-2'-deoxyguanosine (8-OHdG) was recorded in animals consuming fermented goat milk-based diet. In contrast, DNA strand breaks, hydroperoxides, 15-F2t-isoprostanes and protein carbonyl groups were lower in some tissues in animals fed fermented goat milk-based diet, revealing an improvement in both systemic and cellular antioxidant activity of plasma and tissues due to fermented goat milk consumption.

CONCLUSION

Fermented goat milk consumption induces a protective increase in TAS together with lower oxidative damage biomarkers, revealing that the milk protects main cell bioconstituents (lipids, protein, DNA, prostaglandins) from evoked oxidative damage during anemia recovery. © 2016 Society of Chemical Industry.

Fermented goat milk consumption improves melatonin levels and influences positively the antioxidant status during nutritional ferropenic anemia recovery

The aim of the current study was to assess the influence of fermented goat or cow milk on melatonin levels and antioxidant status and during anemia recovery. Eighty male Wistar rats were placed on a pre-experimental period of 40 days and randomly divided into two groups, a control group receiving normal-Fe diet (45 mg kg(-1)) and the Fe-deficient group receiving low-Fe diet (5 mg kg(-1)). Then, the rats were fed with fermented goat or cow milk-based diets with a normal-Fe content or Fe-overload (450 mg kg(-1)) for 30 days. After 30 days of feeding the fermented milks, the total antioxidant status (TAS) was higher in both groups of animals fed fermented goat milk with the normal-Fe content. Plasma and urine 8-OHdG were lower in control and anemic rats fed fermented goat milk. Melatonin and corticosterone increased in the anemic groups during Fe replenishment with both fermented milks. Urine isoprostanes were lower in both groups fed fermented goat milk. Lipid and protein oxidative damage were higher in all tissues with fermented cow milk. During anemia instauration, an increase in melatonin was observed, a fact that would improve the energy metabolism and impaired inflammatory signaling, however, during anemia recovery, fermented goat milk had positive effects on melatonin and TAS, even in the case of Fe-overload, limiting the evoked oxidative damage.

Fermented Goat's Milk Consumption Improves Duodenal Expression of Iron Homeostasis Genes during Anemia Recovery

Despite the crucial roles of duodenal cytochrome b (Dcytb), divalent metal transporter 1 (DMT1), ferritin light chain (Ftl1), ferroportin 1 (FPN1), transferrin receptor 1 (TfR1), and hepcidin antimicrobial peptide (Hamp) in Fe metabolism, no studies have investigated the modulations of these genes during Fe repletion with fermented milks. Analysis included Fe status markers and gene and protein expression in enterocytes of control and anemic animals fed fermented milks. Fermented goat's milk up-regulated enterocyte Dcytb, DMT1, FPN1, and Ftl1 and down-regulated TfR1 and Hamp gene expression in control and anemic animals. Anemia decreased Dcytb, DMT1, and Ftl1 in animals fed fermented cow's milk and up-regulated TfR1 and Hamp expression. Fe overload down-regulated Dcytb and TfR1 in animals fed fermented cow's milk and up-regulated DMT1 and FPN1 gene expression. Fermented goat's milk increased expression of duodenal Dcytb, DMT1, and FPN1 and decreased Hamp and TfR1, improving Fe metabolism during anemia recovery.

Influence of several sources and amounts of iron on DNA, lipid and protein oxidative damage during anaemia recovery

The study was designed to assess the effect of several Fe amounts and sources on haematological parameters, DNA, lipid and protein oxidative damage during the course of Fe-deficiency anaemia recovery. Peripheral DNA damage was assessed using an alkaline comet assay. The brain, liver, erythrocyte and duodenal mucosa lipid peroxidation and protein damage were assessed in control and anaemic rats after Fe repletion with three different sources (FeSO4, haem Fe, and FeSO4 + haem Fe) and amounts (45, 12, and 31 mg Fe/kg diet) of Fe: F diet, H diet or C diet, respectively. After supplying the diets, the haematological parameters studied were recovered; being remarkable is the haemoglobin increase. The DNA damage was lower in rats with the H diet, as revealed by the percentage of DNA in head, tail and Olive tail moment compared in rats with the F (P < 0.001) and C (P < 0.05) diets. Lipid peroxidation was similar in all the tissues, except in the duodenal mucosa which was lower with H and C diets (P < 0.001). The animals fed with C diet showed lower oxidative protein damage in the duodenal mucosa (P < 0.001) and was also lower in the liver and erythrocytes for H and C diets (P < 0.001). No differences were found in the brain under our experimental conditions. In conclusion, Fe supplementation with low doses of haem Fe or combined forms of non-haem and haem Fe (FeSO4 + haem) are efficient in restoring the impaired haematological parameters and prevent the evoked oxidative stress associated with Fe supplements.

Goat milk during iron repletion improves bone turnover impaired by severe iron deficiency

The effect of goat or cow milk-based diets, with either normal Fe content or an Fe overload, on bone turnover and the mineralization process was studied in control and anemic rats during chronic Fe repletion. One hundred eighty male Wistar rats were studied during a pre-experimental period of 40 d in which they were randomly divided into 2 groups, a control group receiving the AIN-93G diet with normal Fe content (45 mg/kg of diet) and the Fe-deficient group receiving the AIN-93G diet with low Fe content (5mg/kg of diet) for 40 d. After the pre-experimental period, the rats were fed for 10, 30, or 50 d with goat or cow milk-based diets with a normal Fe content (45 mg/kg of diet) or an Fe overload (450 mg/kg of diet). In anemic rats, goat milk with normal Fe content increased levels of the biomarker of bone formation N-terminal propeptides of type I procollagen and diminished parathyroid hormone levels after only 10 d of supplying this diet, indicating the beginning of restoration of the bone demineralization induced by the anemia, which was not observed with cow milk. After 30 d of supplying the milk-based diets with normal Fe content or an Fe overload, biomarkers of bone formation and bone resorption were not different between control and anemic rats, indicating that the bone demineralization induced by the Fe-deficiency anemia had recovered, although the process of stabilization of bone turnover began earlier in the animals fed goat milk. In addition, a higher Ca deposit was observed in femur, which positively affects bone mineralization, as well as an increase of Fe in sternum, which indicates that the hematopoietic process essentially recovered earlier on the goat milk diet compared with the cow milk diet.

Severe nutritional iron-deficiency anaemia has a negative effect on some bone turnover biomarkers in rats

BACKGROUND

The role of iron (Fe) in bone formation and disease have not received much attention, a fact that is interesting given the known biochemical role that this mineral has upon collagen maturation together with the high prevalence of Fe-deficiency anaemia worldwide.

AIM

To investigate the changes in bone formation, resorption and mineral content in developing rats with induced nutritional Fe-deficiency anaemia.

METHODS

Thirty male Wistar rats were divided into two groups, a control group receiving AIN-93G diet with normal-Fe content and an anaemic group receiving AIN-93G diet with low-Fe content for 40 days. Both diets were prepared with an adequate calcium (Ca) and phosphorus (P) content. The most representative serum bone turnover biomarkers and femur and sternum calcium and phosphorus content, together with sternum Fe content were determined in both experimental groups.

RESULTS

In anaemic rats, bone matrix formation diminished as revealed by the lower amount of procollagen type I N-terminal propeptide. Bone resorption process increased in Fe deficiency as shown by the increase of serum parathyroid hormone, tartrate-resistant acid phosphatase and levels of degradation products from C-terminal telopeptides of type I collagen released to the serum. In addition, mineralization process was affected by Fe deficiency, because Ca and P content in femur decreased markedly.

CONCLUSIONS

Fe-deficiency anaemia had a significant impact upon bone, affecting bone mineralization, decreasing the matrix formation and increasing bone resorption, therefore it is of great interest to assess bone status in situation of Fe-deficiency anaemia.

Se bioavailability and glutathione peroxidase activity in iron deficient rats

Little information is available on the relationship of Se deposit in target organs and GPx activity in iron deficiency anemia. As red blood cells (RBCs) play a crucial role on Se metabolism and during Fe deficiency anemia a lower count of RBCs is featured, we aimed to investigate the influence of this pathology on Se bioavailability and the relationship with antioxidant status. 20 male Wistar rats were randomly divided into two groups, a control group receiving AIN-93G diet with normal Fe content (45mg/kg diet) and the Fe-deficient group receiving AIN-93G diet with low Fe content (5mg/kg diet) for 40 days. Both diets were prepared with an adequate Se content (0.180mg/kg diet). The digestive and metabolic utilization of Se, the distribution in target organ, the GPx activity and TBARS production were measured after receiving the diets. Se retention increased (P<0.001) in the anemic group, fact that contributes to keep the enzymatic antioxidant activity of GPx in normal levels and the tendency observed is that stored Se increased in the organs, especially in kidney (P<0.01), however, a lower Se deposit was found in sternum of anemic rats (P<0.001). The lower count of RBCs featured in this pathology (P<0.001) causes a decrease of Se concentration in sternum meanwhile the increase in kidney deposit is a consequence of the lower urinary losses (P<0.001).

Goat Milk Feeding Causes an Increase in Biliary Secretion of Cholesterol and a Decrease in Plasma Cholesterol Levels in Rats

The hypocholesterolemic effect of goat milk with respect to cow milk observed in a previous study led us to examine the influence of goat and cow milk in the diet on certain aspects of biliary physiology in normal rats. The fat content in all diets was 10% but the lipid quality was varied: the standard diet was based on virgin olive oil, and the other 2 diets included fat obtained from lyophilized cow milk and goat milk. We characterized the bile secretion, including biliary phospholipid, cholesterol, and bile acid outputs, the interrelation between bile acids and bile lipids, and the lithogenic index. The consumption of goat milk in the diet, compared with that of cow milk, caused an increase in the biliary secretion of cholesterol together with a decrease in plasma cholesterol concentration, whereas values for bile phospholipids, biliary acid concentrations, and the lithogenic index remained normal. Moreover, consumption of this type of milk decreased plasma triglyceride concentration and therefore had a positive effect, similar to that of olive oil (standard diet), on the lipid metabolism; hence, it may be recommended for consumption by the general population.

Effects of goats' or cows' milks on nutritive utilization of calcium and phosphorus in rats with intestinal resection

We analysed the effects of goats' milk (GM) on the nutritive utilization of Ca and P in rats with resection of 50 % distal small intestine in comparison with cows' milk (CM) and a standard non-milk diet. The three test diets contained 200 g protein and 100 g fat/kg. The apparent digestibility coefficient (ADC) of Ca and P were considerably higher in the two groups of rats given the GM diet than those given the other two diets. Ca and P retention did not decrease by effect of intestinal resection with GM diet. In both groups of animals, serum Ca and P levels and ionic Ca were higher in the case of the GM diet than the other two diets, whereas the parathyroid hormone levels were lower. Ca content in femur, sternum and longissimus dorsi muscle was higher in rats given the GM diet. P content in femur and sternum was higher among the two groups of rats given a milk-based diet (GM or CM), especially with GM diet. The GM diet has beneficial effects on nutritive utilization of Ca and P in control rats and those with resection of the distal small intestine.

Beneficial effect of pollen and/or propolis on the metabolism of iron, calcium, phosphorus, and magnesium in rats with nutritional ferropenic anemia

There has been considerable debate regarding the nutritional benefits of pollen and the propolis produced by bees, although most contributions have lacked scientific soundness. This paper describes the possible beneficial effect of their use in pharmacological products in cases of anemic syndrome. We studied the effect of these two natural products on the digestive utilization of iron, calcium, phosphorus, and magnesium, using control rats and rats with nutritional ferropenic anemia. The addition of these products to the diet produced a positive effect on weight gain; this fact could constitute a scientific basis for the application of pollen and propolis as fortifiers. They improve the digestive utilization of iron and the regeneration efficiency of hemoglobin, especially during recovery from an anemic syndrome. They also have a positive effect on phosphocalcic metabolism and maintain an appropiate level of magnesium metabolism. Furthermore, in iron-deficient rats, these natural products palliate, to a large extent, the adverse effects of iron deficiency on calcium and magnesium metabolism as a result of the improvement in the digestive utilization of these minerals.

Iron-manganese interactions in the evolution of iron deficiency

This article examines the evolution of nutritional iron deficiency and the possible interactions with other minerals, such as manganese, in control and iron-deficient rats. The evolution of iron deficiency was studied at 0, 10, 20, 30 and 40 days of providing the animals with an iron-free diet (diet 0). It was found that the critical period in the development of nutritional iron deficiency occurs after 30-40 days without iron, at which moment the organism is unable to maintain hemoglobin levels without endangering the iron-dependent enzymatic groups which, in turn, are essential for life. It was also demonstrated that in a situation of iron deficiency, there occurs a greater absorption of manganese. It should be noted that this greater absorption of manganese is not reflected in the concentration of the mineral in the organs. Therefore, it is evident that the interactions of iron with manganese take place at the digestive level with no apparent consequences being observed at the metabolic level.

The importance of the proportion of heme/nonheme iron in the diet to minimize the interference with calcium, phosphorus, and magnesium metabolism on recovery from nutritional ferropenic anemia

The digestive utilization of Fe and its nutritive interaction with Ca, P, and Mg were studied in rats with nutritional ferropenic anemia. The diet contained 80% ferric citrate and 20% heme iron (80/20 diet). The weight gain, digestive utilization of Fe, and regeneration efficiency of hemoglobin and seric Fe were higher in iron-deficient rats (ID) fed the 80/20 diet than in iron-deficient rats fed the 50/50 diet (Campos et al., 1996). The phospho-calcic metabolism, which is adversely affected in ferropenic anemia, returned to normal values when iron was added to the diet. The digestive utilization of Mg, which fell with the 50/50 diet (Campos et al., 1996), returned to normal values when the ferropenic anemia was reversed with the 80/20 diet. In a state of iron deficiency, certain parameters related to the glucose and lipid metabolism are affected; the glucose and triglycerides values return to a normal range with the 80/20 diet.

Influence of nutritional iron deficiency development on some aspects of iron, copper and zinc metabolism

This paper examines the development of iron (Fe) deficiency and its possible interactions with trace elements such as zinc (Zn) and copper (Cu) by investigating iron-deficient and control rats. The effects of iron deficiency were studied at day 0, 10, 20, 30 and 40 in rats fed on an iron-free diet (diet ID). It was found that the critical period in the development of nutritional iron deficiency occurs after 30 to 40 days without iron supplementation. At this time the organism is unable to maintain haemoglobin levels without endangering the iron-dependent enzymatic groups which are essential for life. It was also demonstrated that in a situation of iron deficiency, there occurs a greater absorption of copper, while that of zinc remains unchanged. As iron deficiency progresses, the levels of copper in the spleen and the sternum increase. It is apparent that iron deficiency provokes more marked alterations in the metabolism of copper than of zinc.

The absorption of iron, calcium, phosphorus, magnesium, copper and zinc in the jejunum-ileum of control and iron-deficient rats

The effects of iron deficiency on the absorption of different dietary sources of iron were studied, together with the interactions between iron, calcium, phosphorus, magnesium, copper and zinc in the jejunum-ileum of control and iron-deficient rats. In this study, three perfusion solutions containing different iron sources: ferric citrate, haemoglobin, and equal parts of ferric citrate and haemoglobin were used. In addition, the same perfusion solutions were used with and without 2,4-dinitrophenol, an inhibitor of oxidative phosphorylation. Iron absorption in anaemic rats was greater than in the controls, except after perfusion with solutions containing haemoglobin. The absorption of calcium, copper and zinc in iron-deficient animals was not significantly affected, while the absorption of phosphorus and magnesium increased, with respect to animals in the control group. After perfusion with solutions containing haemoglobin, the absorption values of calcium, copper and zinc were lower than after ferric citrate in both groups (control and iron-deficient rats).

Effect of source of iron on duodenal absorption of iron, calcium, phosphorous, magnesium, copper and zinc in rats with ferropoenic anaemia

We studied the effects of iron deficiency on the in vivo absorption (by using the intestinal perfusion technique in the duodenum) of different dietary sources of iron (haem, non-haem and equal parts of both forms) and investigated the interactions between iron and calcium, phosphorous, magnesium, copper and zinc in control and iron-deficient rats. Three perfusion solutions containing a different source of iron were used: solution 1, ferric citrate; solution 2, haemoglobin; solution 3, equal parts of ferric citrate and haemoglobin. We also tested the same perfusion solution with 2,4-dinitrophenol (2,4-DNP), an inhibitor or oxidative phosphorylation (solutions 1-I, 2-I and 3-I). In control rats we observed three mechanisms of iron absorption: passive for soluble iron salts, active receptor-mediated for non-haem iron complexes, and active receptor-mediated for haem iron. In anaemic rats iron absorption was greater than in controls, except after perfusion with solution 2 (containing haemoglobin). Absorption increased as a result of both the passive and active, receptor-mediated mechanism for non-haem iron complexes. The active component was influenced by the depletion of haem receptors under severe iron deficiency. The absorption of calcium, copper and zinc in iron-deficient animals was lower than in controls, whereas phosphorus and magnesium absorption were not significantly affected. After perfusion with solution 2 or 3, calcium, copper and zinc absorption were lower than after solution 1. We conclude that ferropoenic anaemia in the rat impairs the absorptive process of those minerals that are absorbed, at the duodenal level mainly via active transport (haem iron, calcium, copper and zinc), but does not affect the active component involved in non-haem iron absorption.

Supplementation of a cereal-milk formula with haem iron palliates the adverse effects of iron deficiency on calcium and magnesium metabolism in rats

Aside from the well known alteration of Fe status in Fe deficiency, this condition has also a negative effect on the bioavailability of Ca and Mg. We studied the influence of the supplementation of a commercial cereal-milk formula with bovine blood on Fe, Ca, P, and Mg metabolism in control and Fe-deficient rats to investigate whether high Fe levels in diet produce some interactions and the possibility of decreasing these latter by a haem-Fe supplementation. The bioavailability in control and Fe-deficient animals was determined as the apparent digestibility coefficient and hemoglobin regeneration efficiency, both of which are accurate estimations of total Fe utilization. Non-fortified cereal-milk formula decreased the apparent digestibility coefficient of Ca and Mg in Fe-deficient rats; the concentrations of these minerals in liver, femur, and sternum were lower than in control animals. However, when the Fe content of the cereal-milk formula was doubled by supplementation with bovine blood, the adverse effects on the digestive utilization of Ca, and especially of Mg, were palliated, the concentration of these two minerals in the organs investigated increased, and the overall Fe status improved in Fe-deficient rats.

Effects of intestinal resection, cholecalciferol and ascorbic acid on iron metabolism in rats

The effect of dietary supplementation with ascorbic acid or cholecalciferol on Fe utilization was studied using the metabolic balance technique, in rats in which 50% of the distal small intestine was removed, or in which the mid small intestine was transected and reanastomosed (controls). Three different diets were used. The first (basal diet) contained (g/kg dry wt): protein (casein + 50 mg D,L-methionine/g) 120 and fat (medium-chain triacylglycerols, olive oil and sunflower oil, in equal parts) 40. The other diets were obtained by adding ascorbic acid (150 mg/kg diet) or cholecalciferol (0.4 mg/kg diet) to the basal diet. Apparent digestibility coefficient (ADC) and Fe retention were significantly lower in resected animals than in their respective control groups (transected rats). However, the addition of ascorbic acid or cholecalciferol to the basal diet increased the ADC and Fe retention in both transected and resected rats. Five weeks after surgery, resection also resulted in a reduced concentration of Fe in the sternum, but did not reduce the concentration of haemoglobin or serum Fe total Fe-binding capacity or the concentration of Fe in liver, testes, femur or muscle (longissimus dorsi). Supplementation with ascorbic acid increased serum Fe concentration, while the concentration of Fe in muscle was reduced by supplementation with both ascorbic acid and cholecalciferol. Neither supplementation had any effect on the Fe concentration in other tissues, on haemoglobin concentration or plasma total Fe-binding capacity. Thus, supplementation with ascorbic acid or with cholecalciferol increased Fe absorption and reduced the concentration of Fe in muscle.

Copper malabsorption after intestinal resection in rats. Effects of cholecalciferol and ascorbic acid

Dietary modifications can partly compensate for the alterations in copper homeostasis caused by distal intestinal resection, by improving biliary function. We studied the effects of resecting 50% of the distal small intestine (DSI) on copper status in rats fed three semisynthetic diets (basal diet, and basal diet with cholecalciferol or ascorbic acid). Intestinal resection significantly decreased the digestive (apparent digestibility coefficient; ADC) and metabolic utilization (balance) of copper 1 month after surgery. However, the supplementation of the basal diet with cholecalciferol attenuated the negative impact of surgery, leading to small differences in Cu ADC and Cu balance between transected and resected rats. Ascorbic acid also enhanced copper retention. Copper status was not as markedly affected by intestinal resection as digestive utilization 1 month after the operation. The beneficial effects of cholecalciferol and ascorbic acid at the digestive and metabolic levels suggest ways to lessen the impact of intestinal resection, and to avoid possible long-term postabsorptive alterations in copper distribution.

Effect of intestinal resection, type of dietary fat and time on biliary lipid secretion in rats

The effects of time and the type of dietary fat on biliary physiology in rats with 50% resection of the distal small intestine were investigated. The effects of ursodeoxycholic acid as an exogenous source of bile acid added to the diet were also studied. The fat composition of all diets was the same in quantitative terms (4%), and differed only in the type of lipid supplied: olive oil (diet A) or one-third medium chain triglycerides, one-third sunflower seed oil and one-third olive oil (diet B). In resected rats given diet A for 1 or 3 months, there was a decrease in biliary secretion of cholesterol and phospholipids, and in the lithogenic index, with respect to the control group. Resected rats fed diet B for 1 or 3 months showed increases in biliary secretion of cholesterol and phospholipids, and in the lithogenic index, in comparison with resected rats fed diet A. The addition of ursodeoxycholic acid to diet B led to the decoupling of bile acid and bile lipid secretion.

Influence of ileal resection, type of diet and ursodeoxycholic acid on biliary secretion in rats

We studied the effects of the type of dietary fat and of ursodeoxycholic acid, an exogenous bile acid added to the diet, on bile physiology in rats with 50% resection of the distal small intestine. The amount of fat was the same (4%) in all diets assayed, which differed only in the type of fat, (olive oil in diet A, and 1/3 medium-chain triglycerides, 1/3 sunflower oil and 1/3 olive oil in diet B). The removal of 50% of the distal small intestine raised the de novo hepatic synthesis of bile acids with respect to controls, regardless of whether diet A or diet B was given. The addition to diet B of ursodeoxycholic acid decreased bile flow and osmotic activity of bile acid in resected rats and raised bile acid-independent bile flow in comparison to resected rats given diet B without ursodeoxycholic acid.

Influence of dietary fat on nutritive utilization of protein in intestinally resected rats

The effects of different types of dietary fat on the digestive and metabolic utilization of protein were studied in rats with 50% resection of the distal small intestine and in sham-operated controls one month after surgery. The digestive utilization of protein was not significantly affected in intact animals when olive oil was replaced by butter as the dietary source of fat. In resected rats given either type of diet the apparent digestibility coefficient of protein declined significantly in comparison to intact controls. Intestinal resection decreased the retention of nitrogen significantly in rats given olive oil. The replacement of 2/3 of the dietary supply of olive oil with 1/3 medium chain triglycerides and 1/3 sunflower seed oil improved the metabolic utilization of protein in comparison to resected rats fed olive oil or butter as the only source of dietary fat. However, the addition of ursodeoxycholic acid to the diet containing equal parts of olive oil, medium chain triglycerides and sunflower seed oil failed to improve the metabolic utilization of protein in comparison to that seen in rats given olive oil only. Serum concentrations of total protein, urea and creatinine, albeit with slight changes in the first, remained within normal limits. Despite the lower retention of nitrogen in resected rats, these animals maintained homeostasis without resorting to muscular protein.

Nutritive utilization of protein and digestive utilization of fat in two commercial diets designed for clinical enteral nutrition

The digestive and metabolic utilization of protein (50% lactoalbumin + 50% casein) and fat (43.0% butter, 29.5% olive oil, 14.7% soy oil, 9.8% MCT and 3.0% lecithin) provided by two commercial diets used in clinical enteral nutrition (normoproteic, 16.1% protein and 20.8% fat, and hyperproteic, 23.1% protein and 14.9% fat), was studied in adult rats (mean body weight 180 g). The diet containing the greater amount of protein improved the digestive utilization of nitrogen, and although nitrogen retention was optimal, it failed to rise further when the dietary protein supply was increased. The digestive utilization of fat in both diets was excellent.

Nutritive utilization of calcium in rats: effects of dietary fat components and vitamin D3 on intestinal resected rats

The nutritive utilization of calcium was studied in adult rats in which 50% of the distal small intestine (DSI) had been resected and in sham-operated controls one month and three months after the operation. Resection of half the DSI reduced the digestive utilization of Ca as reflected by mineral content in bone. Three months after resection, nutritive utilization of Ca had still not recovered. Feeding the resected rats with a diet in which fat content consisted of equal parts of medium-chain triglycerides (MCT), sunflower seed oil, and olive oil failed to improve nutritive utilization of Ca after one or three months in comparison with a diet containing olive oil as the only source of lipids. Supplementation with vitamin D3 (0.04 mg/100 g diet) enhanced nutritive utilization of Ca in resected rats after one month, the beneficial effect becoming much more patent after three months. At the dose used, vitamin D3 favored calcium deposition in bone tissue. Serum levels of Ca remained unchanged under all experimental conditions, both one month and three months after 50% DSI resection.