[Iron metabolism: current concepts of an essential micronutrient]. / Metabolismo del hierro: conceptos actuales sobre un micronutriente esencial.

Iron is an essential micronutrient involved in multiple biochemical and physiological process. In this review we discuss the most relevant aspect of its metabolism in order to reach a better comprehension of the relevant roll that this micronutrient plays in human health.

Stabilized ferrous gluconate as iron source for food fortification: bioavailability and toxicity studies in rats.

The iron bioavailability and acute oral toxicity in rats of a ferrous gluconate compound stabilized with glycine (SFG), designed for food fortification, was studied in this work by means of the prophylactic method and the Wilcoxon method, respectively. For the former studies, SFG was homogeneously added to a basal diet of low iron content, reaching a final iron concentration of 20.1 +/- 2.4 mg Fe/kg diet. A reference standard diet using ferrous sulfate as an iron-fortifying source (19.0 +/- 2.1 mg Fe/kg diet) and a control diet without iron additions (9.3 +/- 1.4 mg Fe/kg diet) were prepared in the laboratory in a similar way. These diets were administered to three different groups of weaning rats during 23 d as the only type of solid nourishment. The iron bioavailability of SFG was calculated as the relationship between the mass of iron incorporated into hemoglobin during the treatment and the total iron intake per animal. This parameter resulted in 36.6 +/- 6.2% for SFG, whereas a value of 35.4 +/- 8.0% was obtained for ferrous sulfate. The acute toxicological studies were performed in two groups of 70 female and 70 male Sprague-Dawley rats that were administered increasing doses of iron from SFG. The LD50 values of 1775 and 1831 mg SFG/kg body wt were obtained for female and male rats, respectively, evidencing that SFG can be considered as a safe compound from a toxicological point of view.

Current knowledge of iron metabolism.

Iron plays many roles in human physiology. In this article, we summarize the basic and current knowledge of this essential micronutrient on human metabolism.

Bioavailability of Petit-Suisse cheese as food vehicle for iron fortification estimated by the prophylactic method.

Microencapsulated ferrous sulfate (SFE-171) and ferric orthophosphate in Petit-Suisse cheese were examined for iron bioavailability by the prophylactic method. The iron sources were industrially added to different samples of Petit-Suisse cheese, which were mixed with other food components in our laboratory before use. A reference standard diet inclusive of nonmicroencapsulated ferrous sulfate and a control diet low in iron content were prepared in the laboratory. The final iron content in the fortified diets was approximately 15 mg Fe/kg diet. These diets were administered to weaning rats for 23 days. The iron bioavailability was evaluated as the ratio of iron incorporated into hemoglobin to oral iron intake, thereby being estimated as 62.6 +/- 8.8% for ferrous sulfate and 59.2 +/- 10.6% for SFE-171, which were significantly effective at p < 0.01 compared to 43.4 +/- 10.5% for ferric orthophosphate. It thus turned out that SFE-171 was stable through industrial processing with Petit-Suisse cheese as the food vehicle and served as an iron fortifier equal to ferrous sulfate in bioavailability.

Zinc and iron interactions evaluated between different mineral sources in different nutritional matrixes.

We compared the absorption of BioZn, SFE-171, SO4Fe (reference standard) and SO4Zn (reference standard) alone or in combination in water and in an infant dessert. When mineral interactions were evaluated, zinc and iron were administered in a 1:1 molar relation. There 160 rats divided in 16 groups of 10 animals each which received: SO(4)65Zn, Bio65Zn, SO(4)65Zn + SO4Fe, Bio65Zn + SFE-171, SO(4)59Fe, 59SFE-171, SO(4)59Fe + SO4Zn and 59SFE-171 + BioZn either in water or an infant dessert. The results showed that BioZn has bioavailability similar to SO4Zn both in water (23.36 +/- 3.14% vs. 21.48 +/- 6.03%. respectively) and in an infant dessert (19.89 +/- 3.27% vs. 18.31 +/- 4.76%, respectively). When these zinc compounds were administered with iron no statistical difference of zinc absorption was found (Bio65Zn + SFE-171 in water 22.70 +/- 6.30%, Bio65Zn + SFE-171 in the infant dessert 18.07 +/- 5.89%, SO(4)65Zn + SO4Fe in water 24.67 +/- 5.70% and SO(4)65Zn + SO4Fe in the infant desert 20.56 +/- 5.20%). For iron, the absorption of 59SFE-171 in water was higher (p < .01) than SO(4)59Fe in water and 59SFE-171 + BioZn in water (32.35 +/- 8.32% vs. 26.27 +/- 8.83% vs. 23.69 +/- 8.37%, respectively). Iron absorption from SO(4)59Fe in water was higher (p < .01) than SO(4)59Fe + SO4Zn in water (26.27 +/- 8.83% vs. 20.21 +/- 8.72%, respectively). Iron absorption in the infant dessert was higher (p < .01) for 59SFE-171 + BioZn than SO(4)59Fe, 59SFE-171 and SO(4)59Fe + SO4Zn (22.81 +/- 6.97% vs. 16.12 +/- 6.14% vs. 16.90 +/- 6.23% vs. 15.04 +/- 6.25%, respectively). Statistical differences (p < .01) were found between iron absorption from 59SFE-171 in water and the infant dessert (32.35 +/- 8.32% vs. 16.90 +/- 6.23%, respectively) and for SO(4)59Fe (26.27 +/- 8.83% vs. 16.12 +/- 6.14% respectively). Zinc and iron interactions evaluated in a 1:1 molar relation of the minerals were observed only for iron absorption in water but not in infant dessert. No negative effect was found for zinc absorption neither in water nor in infant dessert.

The role of zinc in the growth and development of children.

This review concerns the importance of zinc in growth, development, and cognitive function in children and the deleterious consequences of its deficiency on children's health. Possible strategies to overcome zinc deficiency and the results of some supplementation trials are discussed.

Bioavailability of microencapsulated ferrous sulfate in powdered milk produced from fortified fluid milk: a prophylactic study in rats.

OBJECTIVE: We investigated the iron bioavailability of microencapsulated ferrous sulfate (SFE-171) in a diet based on powdered milk by using the prophylactic method in rats. METHODS: The SFE-171 was added into fluid milk and industrially processed into powdered milk, which was then mixed in our laboratory with a normalized diet (17.2 +/- 2.1 mg Fe/kg). A reference standard diet using ferrous sulfate as iron-fortifying source (19.8 p+/- 2.9 mg Fe/kg) and a control diet without added iron (4.6 +/- 0.8 mg Fe/kg) were prepared in the laboratory in a similar way. These diets were administered to different groups of weaning rats for 28 d as the only solid nourishment. The iron bioavailability of the different sources was calculated as the relation between the mass of iron incorporated into hemoglobin during the treatment and the total iron intake per animal. RESULTS: The iron bioavailability values of SFE-171 and ferrous sulfate in the fortified diets were 41.6 +/- 6.6% and 42.6 +/- 4.2%, respectively; these results were significantly higher (P < 0.01) than the iron bioavailability of the control diet (28.8 +/- 8.1%). CONCLUSION: These results showed that iron-fortified powdered milk can be produced from fluid milk fortified with SFE-171. The bioavailability of SFE-171 in this rat model was not altered by the manufacturing process.

Fortification strategies to combat zinc and iron deficiency.

Food fortification is an important strategy to combat iron and zinc deficiency. This review covers the basic concepts of food fortification, as well as its advantages and disadvantages. The main characteristics of the most common zinc and iron compounds used in this procedure are also analyzed.

Importancia del empleo de un patrón de 129I para la medición de 125I / Usefulness of a 129I for 125I measurement

En el presente trabajo se muestran las ventajas de la utilización de un patrón de 129I para comprobar diariamente que la respuesta del equipo de detección es constante para el 125I y poder determinar además la eficiencia para dicho nucleido. Una alternativa para conocer ese valor consiste en la aplicación de un método de coincidencia. La comparación de los resultados logrados con uno y otro método, demuestra que ambos valores de eficiencia son iguales. Por otra parte se analizan algunas cuestiones relacionadas con las ecuaciones teóricas utilizadas

Importancia del empleo de un patrón de 129I para la medición de 125I / Usefulness of a 129I for 125I measurement

En el presente trabajo se muestran las ventajas de la utilización de un patrón de 129I para comprobar diariamente que la respuesta del equipo de detección es constante para el 125I y poder determinar además la eficiencia para dicho nucleido. Una alternativa para conocer ese valor consiste en la aplicación de un método de coincidencia. La comparación de los resultados logrados con uno y otro método, demuestra que ambos valores de eficiencia son iguales. Por otra parte se analizan algunas cuestiones relacionadas con las ecuaciones teóricas utilizadas (AU)