Goat milk consumption modulates liver divalent metal transporter 1 (DMT1) expression and serum hepcidin during Fe repletion in Fe-deficiency anemia.

Iron deficiency is the most prevalent micronutrient deficiency worldwide. In spite of the crucial role of hepatocyte divalent metal transporter 1 (DMT1) and hepcidin in Fe metabolism, to date, no studies have directly tested the role of these proteins in liver Fe metabolism during Fe repletion after induced Fe-deficiency anemia. Therefore, the aim of the current study was to assess the effect of goat or cow milk-based diets on Fe metabolism in one of the main body storage organs, the liver, during the course of Fe repletion with goat or cow milk-based diets in anemic rats. Animals were placed on a preexperimental period of 40 d, a control group receiving a normal-Fe diet and the Fe-deficient group receiving a low-Fe diet (5 mg of Fe/kg of diet). Rats were fed for 30 d with goat or cow milk-based diets with normal Fe content (45 mg of Fe/kg of diet). The hematological parameters, serum hepcidin, hepatosomatic index, liver Fe content, and liver DMT1 expression were determined. During the recovery of the anemia with milk-based diets, the restoration of liver Fe content and hematological parameters, especially with goat milk, increased the red blood cell count, favoring the oxygen supply and weight gain. Moreover, goat milk consumption potentiates liver DMT1 expression, enhancing Fe metabolism and storage. In addition, the increase in serum hepcidin in anemic rats observed in the current study also explains and supports the higher liver Fe content after supplying goat milk, because it blocks the liberation of Fe from hepatocytes, increasing its storage in liver.

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.

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.

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.

Beneficial effect of goat milk on bioavailability of copper, zinc and selenium in rats.

We studied the effects of dietary inclusion of freeze-dried goat and cow milk on the utilization of copper, zinc and selenium, and on the metabolic fate of copper and zinc, in rats using a standard (non-milk) control diet recommended by the American Institute of Nutrition and diets based on goat or cow milk. For animals given the goat milk diet, the apparent digestibility coefficient (ADC) of copper is similar to that obtained with the standard diet and higher than that in animals given the cow milk diet. The copper balance was higher among the rats given the goat milk and the standard diets than among those given cow milk. The ADC and retention of zinc and selenium were higher for the goat milk diet than for the other two diets. The copper content in the kidneys and in the femur was greater when the animals consumed a goat milk diet than a cow milk diet. Zn deposits in femur, testes, liver, kidney, heart and longissimus dorsi muscle were greatest with the goat-milk diet, followed by the standard diet and were lowest for the rats given cow-milk diet. This study shows that the goat-milk has an important and beneficial effect on the bioavailability of copper, zinc and selenium.

Influence of goat and cow milk on the digestive and metabolic utilization of calcium and iron.

The effects of goat and cow milk on the digestive and metabolic utilization of calcium and iron were studied in rats using a standard (non-milk) control diet. The digestive utilization of calcium is greater when the animals consume the goat-milk-based diet rather than that based on cow milk or the standard diet. The digestive utilization of iron, however, is similar for the goat-milk diet and the standard diet, and in both cases superior to that based on cow milk. The calcium content in the femur, sternum and Longissimus dorsi muscle (L.D. muscle) provides an indication of what happens during the utilization of the mineral; more is deposited when the rats consume a milk-based diet, particularly one based on goat milk. The iron content in the reserve organs, namely the liver and the spleen, is greater with the standard diet and the goat milk diet than with that containing cow milk. There is an obviously beneficial effect of goat milk on the metabolism of calcium and iron, which minimizes any interaction between the two minerals.

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.

Effects of type of dietary fat and cholecalciferol on magnesium absorption in rats with intestinal resection.

We studied the effect of type of dietary fat and supplementation with cholecalciferol on magnesium absorption in the duodenum, jejunum and proximal colon in rats with resection of 50% of the distal small intestine. Magnesium transport against the concentration gradient was found to occur in all three intestinal segments, although transport increased significantly only in the proximal colon of intestinally resected rats fed a diet supplemented with cholecalciferol at a rate of 0.425 mg/kg diet and mixture of equal parts of medium chain triglycerides, sunflower oil and olive oil as the source of dietary fat (diet B), in comparison with magnesium absorption in control rats subjected to intestinal transection and fed diet B, and in resected rats fed a diet without cholecalciferol supplementation and in which olive oil was the sole source of dietary fat (diet A). Magnesium absorption due to active and passive transport together, was greater in resected than in transected rats in all three intestinal segments, although the difference was significant only in the jejunum (the segment closest to the anastomosis), because of the greater increase in mucosal mass in resected animals. When the three intestinal segments were compared, magnesium absorption in favour of and against the concentration gradient in the proximal colon was significantly greater than in the duodenum or the jejunum, in resected and transected animals fed diet A or diet B. These findings show that the colon is the segment that most efficiently absorbs magnesium in rats with intestinal resection, especially when diet B is given.

Influence of dietary fat components and intestinal resection on iron, zinc and copper metabolism in rats.

The effect of resecting 50% of the distal small intestine (DSI) on iron, zinc and copper nutritive utilization was studied in rats fed two different types of diet: a standard diet containing 4% olive oil (A) and a diet containing different sources of fat (1/3 olive oil, 1/3 sunflower oil and 1/3 medium chain triglycerides) (B). One month and 7 days after surgery, intestinal resection led to a deterioration in digestive (ADC) and metabolic (balance) utilization of iron, zinc and copper. To assess trace metal postresectional homeostasis, we also measured these mineral concentrations in whole blood, plasma and several organs (liver, femur, sternum, longissimus dorsi muscle and testes). Our findings showed no significant differences in iron, zinc and copper concentrations between the organs, suggesting that the observed decrease in digestive and metabolic efficiency of these minerals was not markedly reflected at the postabsorptive level, since the distribution of the trace elements in the whole organism remained unchanged. We conclude that one month and 7 days after this surgical intervention, adaptive mechanisms are well developed in resected rats fed a diet with an adequate mineral supplement.

Calcium absorption in rats with distal intestinal resection: influence of type of dietary fat, cholecalciferol and nature of the adaptative response.

The effects of dietary fat and supplementation with cholecalciferol on calcium absorption at different luminal concentrations (2.07 mmol/l and 2.07 mmol/l with 0.5 mmol/l 2,4-dinitrophenol and 8.20 mmol/l) were studied in vivo in the perfused duodenum, residual jejunum and proximal colon of rats with resection of 50% of the distal small intestine, as well as the nature of the adaptative response (passive or active). Changing the source of dietary fat (diet B, containing 1/3 medium chain triglycerides, 1/3 olive oil, 1/3 sunflower oil) increased calcium absorption, preferentially via active transport, in both transected and resected rats. Supplementation of diet B with cholecalciferol further enhanced intestinal calcium absorption, especially in the colon. These results suggest the importance of diet in the adaptive processes and confirm that active mechanisms of transport adapt more readily to intestinal resection than do passive mechanisms.

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.

Effects of iron replenishment on iron, calcium, phosphorus and magnesium metabolism in iron-deficient rats.

We investigated the effect of Fe deficiency on the nutritive utilization of Fe, Ca, P and Mg in rats. Aside from the well known depletion of Fe in liver, femur and sternum with low values of Hb, Fe deficiency impaired Ca, P and Mg metabolism at different degrees. Iron deficiency altered Mg absorption, lowered the concentration of Ca in the liver, femur and sternum, raised the concentration of P and Mg in the liver, and decreased P in the femur. The altered status was not completely rectified by iron supplementation as the animals were still slightly anemic at the end of the study. The second purpose of the study was to evaluate the ability of three iron compounds (ferric citrate, ferrous sulfate and ferrous ascorbate) to correct the undesirable effects of Fe deficiency. Ten days after treatment with these diets, Fe-deficient rats still had reduced Mg absorption, especially those fed ferric citrate. The concentrations of hemoglobin approached normal values in all groups; however, serum Fe remained low, indicating that Fe reserves were still depleted. Hepatic and femoral Fe concentrations were also lower in all Fe-deficient groups regardless of the diet given, compared with their respective controls, whereas Fe concentrations in the sternum increased significantly with all three diets, suggesting an increase in erythropoiesis. The concentration of Ca, P and Mg in liver approached normal values, and appeared to normalize in the femur, except that Ca and P concentrations remained low with the citrate diet. In the sternum, a site assumed to have higher requirements for these minerals, the concentrations of Ca, P and Mg also increased. These findings indicate that Fe is involved in the bone mineralization, and that in physiological terms, Fe interacts favorably with Ca, P and Mg metabolism, since Fe deficiency altered the status of these metals. These findings also suggest that ferrous ascorbate and ferrous sulfate were more effectively absorbed than was ferric citrate.

Influence of intestinal resection and type of diet on digestive utilization and metabolism of magnesium in rats.

The influence of intestinal resection and type of diet on nutritive utilization of magnesium was studied in rats in which 50% of the distal small intestine was removed and in sham-operated controls. Nutritive parameters were analyzed after feeding the rats different diets for one or three months after surgery. Loss of 50% of the distal small intestine reduced digestive utilization of Mg as reflected in the mineral content of bone, however digestive and metabolic utilization of Mg were seen to recover by three months postsurgery. When dietary fat was supplied as equal parts of medium chain triglycerides, sunflower seed oil and olive oil instead of 100% olive oil, Mg absorption and retention were enhanced in resected rats after one month with the beneficial effects on Mg metabolism becoming even more marked after three months. One month after resection, dietary supplementation with vitamin D3 clearly stimulated digestive utilization of Mg. Although this effect was less notable at three months, nutritive utilization of Mg remained higher than in resected rats fed a diet lacking vitamin D3 supplementation. Dietary levels of vitamin D3 favored the deposition of Mg in bone tissue.

Nutritive utilization of phosphorus in the rat: influence of intestinal resection and dietary medium chain triglycerides and vitamin D3.

The effects of intestinal resection and diet on the digestive and metabolic utilization of phosphorus were studied in adult rats from which 50% of the distal small intestine had been removed and in sham-operated controls. Metabolic parameters were measured both 1 and 3 months after surgery. The loss of half of the distal small intestine led to a decline in digestive utilization of phosphorus 1 month after surgery as reflected in bone mineral content. Digestive efficiency had improved by 3 months after surgery. One month's feeding with a diet in which fat was provided as equal parts of medium chain triglycerides, sunflower seed oil and olive oil instead of 100% olive oil enhanced phosphorus absorption and retention, although this improvement was less evident after 3 months. The negative effects of distal small intestine resection on the nutritive utilization of phosphorus were not only palliated but significantly enhanced by supplementing the diet with vitamin D3 at a rate of 0.08 mg/100 g diet. This dose is within physiological limits, and favors phosphorus deposition in bone tissue.

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).

[The effect of intestinal resection and dietary fat quality on the nutritional utilization of fat]. / Influencia de la resección intestinal y de la calidad lipídica de la dieta sobre la utilización nutritiva de la grasa.

The influence of the quality of dietary fat on digestive and metabolic utilization of fat, serum levels of cholesterol and triglycerides and the relative percentages of serum fatty acids was studied in rats in which 50% of the distal small intestine (DSI) was resected and in sham-operated controls. Nutritive parameters were measured 1 month after surgery. The fat components of the diets were: olive oil, butter and equal parts of medium chain triglycerides (MCT), olive oil and sunflower seed oil. There was no changes in digestive utilization of fat in shamoperated controls with either dietary sources of fat, olive oil or butter. The removal of 50% of the distal small intestine led to a decline in the digestive utilization of fat (ADC) in both test diets. When dietary fat was supplied as equal parts of MCT, olive oil and sunflower seed oil instead of 100% olive oil (diet C), digestive utilization of fat was enhanced in resected rats. When ursodeoxycholic acid (UDCA) was added to diet C, digestive utilization of fat remained high, reaching values as elevated as those in sham-operated controls. At the metabolic level, resection of half the DSI led to a significant decrease in serum triglycerides and cholesterol levels, independently of type of dietary fat tested. The type of diet, as well as intestinal resection, do not led to an essential fatty acid deficiency in serum lipids; it is only a reflect of the supplemented diet fat contents.

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.

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.

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.