Sandra Fernandes Arruda

Vitamin A deficiency increases hepcidin expression and oxidative stress in rat.

OBJECTIVE The interaction between vitamin A and iron status has been widely reported; however, the exact mechanism involved in this interaction has not been well characterized. The present study investigated the mechanism involved in tissue iron accumulation and changes in the oxidative status in vitamin A-deficient rats. METHODS Rats were treated with a control diet, a vitamin A-deficient diet, or a vitamin A/iron-deficient diet for 57 d. The animals were sacrificed; the blood, liver, and spleen were collected for biochemical analysis. Analysis of variance or Mann-Whitney tests were used to compare groups and Pearsons or Spearmans tests to investigate the bivariate correlation. RESULTS Vitamin A deficiency increased liver hepcidin mRNA and iron spleen concentrations; however, iron deficiency in vitamin A-deficient rats deeply inhibits liver hepcidin mRNA expression and significantly increases divalent metal transporter-1 mRNA levels. Liver ferroportin and hereditary hemochromatosis gene mRNA levels did not change in either treatment. In the vitamin A-deficient groups, liver carbonyl protein increased, whereas catalase and glutathione S-transferase activities decreased, suggesting that vitamin A protects the liver against protein oxidation. A significant positive correlation was found between lipid oxidative damage and iron concentration in the liver and spleen (r = 0.611, P = 0.007; r = 0.558, P = 0.025, respectively). CONCLUSION These results suggest that vitamin A maintains iron homeostasis by the modulation of liver hepcidin expression. The increase of lipid peroxidation in vitamin A deficiency seems to be iron dependent, whereas protein oxidation is not.

Minerals, phytic acid and tannin contents of 18 fruits from the Brazilian savanna.

The present study evaluated the nutritious potential of 18 fruits, all native of the Brazilian Cerrado biome. Mineral contents were determined by inductively coupled plasma atomic emission; phytic acid and tannin contents by a colorimetric and titrimetric method, respectively; and the potential mineral bioavailability by the molar ratio of phytic acid/mineral. Baru nut showed the highest zinc, copper, iron, phosphorus and magnesium content, and, together with macaúba, showed also the highest calcium content and caloric value. Macaúba, pitomba, ingá and murici fruits were classified as a source of iron. The jatoba and baru nut had the highest concentration of phytic acid and tannins. The [phytic acid]/[iron] and [phytic acid]/[zinc] molar ratios were higher than the critical values (14 and 10, respectively) only in the baru nuts, which suggests that iron and zinc bioavailability is low in this nut. The [phytic acid]/[calcium] molar ratios were lower than the critical value (1.56) in all analyzed fruits, which suggests that calcium is bioavailable in the fruits.

Dietary Iron Concentration May Influence Aging Process by Altering Oxidative Stress in Tissues of Adult Rats

Iron is an essential element. However, in its free form, iron participates in redox-reactions, leading to the production of free radicals that increase oxidative stress and the risk of damaging processes. Living organisms have an efficient mechanism that regulates iron absorption according to their iron content to protect against oxidative damage. The effects of restricted and enriched-iron diets on oxidative stress and aging biomarkers were investigated. Adult Wistar rats were fed diets containing 10, 35 or 350 mg/kg iron (adult restricted-iron, adult control-iron and adult enriched-iron groups, respectively) for 78 days. Rats aged two months were included as a young control group. Young control group showed higher hemoglobin and hematocrit values, lower levels of iron and lower levels of MDA or carbonyl in the major studied tissues than the adult control group. Restricted-iron diet reduced iron concentrations in skeletal muscle and oxidative damage in the majority of tissues and also increased weight loss. Enriched-iron diet increased hematocrit values, serum iron, gamma-glutamyl transferase, iron concentrations and oxidative stress in the majority of tissues. As expected, young rats showed higher mRNA levels of heart and hepatic L-Ferritin (Ftl) and kidneys SMP30 as well as lower mRNA levels of hepatic Hamp and interleukin-1 beta (Il1b) and also lower levels of liver protein ferritin. Restricted-iron adult rats showed an increase in heart Ftl mRNA and the enriched-iron adult rats showed an increase in liver nuclear factor erythroid derived 2 like 2 (Nfe2l2) and Il1b mRNAs and in gut divalent metal transporter-1 mRNA (Slc11a2) relative to the control adult group. These results suggest that iron supplementation in adult rats may accelerate aging process by increasing oxidative stress while iron restriction may retards it. However, iron restriction may also impair other physiological processes that are not associated with aging.

Iron status and oxidative stress biomarkers in adults: a preliminary study.

OBJECTIVE Although essential to many vital processes, iron catalyzes reactions that produce reactive oxygen species, which are associated with the increased risk of non-communicable chronic diseases and precocious aging. This study investigated whether ferritin, hemoglobin concentration, and dietary iron consumption are related to oxidative stress biomarkers in adults. METHODS Data were collected from 134 allegedly healthy subjects >18 y of age who were randomly selected to participate in a cross-sectional study as part of the pilot project Prevalence of Risk Factors for Non-communicable Chronic Diseases in the Federal District, Brazil (VIVA Saúde-DF). Serum ferritin, malondialdehyde (MDA) and protein carbonyl concentrations, hemoglobin, and dietary iron consumption were analyzed. RESULTS A weak positive correlation (r = 0.189, P = 0.032) and association (P = 0.046) was observed for serum ferritin and MDA. Hemoglobin concentrations were positively associated with serum MDA (P = 0.040). Dietary iron intake and serum protein carbonyl concentrations showed a weak positive correlation (r = 0.173, P = 0.046) for all subjects. Iron intake by women was positively associated with serum protein carbonyl (P = 0.03). A lower serum MDA concentration was found in ferritin-deficient subjects (P = 0.015) and men with anemia (P = 0.011). CONCLUSION These results suggest that low levels of iron may reduce oxidative stress.

Vitamin A deficiency modulates iron metabolism via ineffective erythropoiesis.

Vitamin A modulates inflammatory status, iron metabolism and erythropoiesis. Given that these factors modulate the expression of the hormone hepcidin (Hamp), we investigated the effect of vitamin A deficiency on molecular biomarkers of iron metabolism, the inflammatory response and the erythropoietic system. Five groups of male Wistar rats were treated: control (AIN-93G), the vitamin A-deficient (VAD) diet, the iron-deficient (FeD) diet, the vitamin A- and iron-deficient (VAFeD) diet or the diet with 12 mg atRA/kg diet replacing all-trans-retinyl palmitate by all-trans retinoic acid (atRA). Vitamin A deficiency reduced serum iron and transferrin saturation levels, increased spleen iron concentrations, reduced hepatic Hamp and kidney erythropoietin messenger RNA (mRNA) levels and up-regulated hepatic and spleen heme oxygenase-1 gene expression while reducing the liver HO-1 specific activity compared with the control. The FeD and VAFeD rats exhibited lower levels of serum iron and transferrin saturation, lower iron concentrations in tissues and lower hepatic Hamp mRNA levels compared with the control. The treatment with atRA resulted in lower serum iron and transferrin concentrations, an increased iron concentration in the liver, a decreased iron concentration in the spleen and in the gut, and decreased hepatic Hamp mRNA levels. In summary, these findings suggest that vitamin A deficiency leads to ineffective erythropoiesis by the down-regulation of renal erythropoietin expression in the kidney, resulting in erythrocyte malformation and the consequent accumulation of the heme group in the spleen. Vitamin A deficiency indirectly modulates systemic iron homeostasis by enhancing erythrophagocytosis of undifferentiated erythrocytes.

Regional low-cost diet supplement improves the nutritional status of school children in a semi-arid region of Brazil.

Non-governmental organizations (NGOs) in Brazil have used an alternative diet supplement known as multimixture (MM) composed of bran cereals, cassava leaf powder and eggshell powder. This study investigated the effectiveness of this MM supplement used concomitantly with other actions to improve children’s health. Thirty-one students enrolled in a rural school were examined for anthropometric and hematologic measures before and after the consumption of diet supplemented with MM. The results were compared with those from control group (n = 26) who consumed the same diet without MM. At the end of the study, the NGO intervention provided a beneficial effect on the nutritional status of children, since it improved their blood parameters and reduced the anemia independently of MM supplementation. The average height/age was significantly higher only in the group that received MM. The supplementation of the deficient diets with MM contributed significantly to the improvement of the children’s stature.

Brazilian savanna fruits contain higher bioactive compounds content and higher antioxidant activity relative to the conventional red delicious apple.

The bioactive compounds content and the antioxidant activity (AA) of twelve fruits native to the Cerrado were compared with the Red Delicious apple by means of the antiradical efficiency (using the 2,2-diphenyl-1-picrylhydrazil assay/DPPH), ferric reducing antioxidant power (FRAP) and the β-carotene/linoleic system. The antiradical efficiency (AE) and the kinetic parameters (Efficient concentration/EC50 and time needed to reach the steady state to EC50 concentration/TEC50) of the DPPH curve were also evaluated for comparison with the Trolox equivalent (TE) values. A strong, significant and positive correlation was observed between the TE and AE values, whereas a weak and negative correlation was observed between TE and EC50, suggesting that the values of AE and TE are more useful for the determination of antiradical activity in fruits than the widely used EC50. The total phenolic content found in the fruits corresponded positively to their antioxidant activity. The high content of bioactive compounds (flavanols, anthocyanins or vitamin C) relative to the apple values found in araticum, cagaita, cajuzinho, jurubeba, lobeira, magaba and tucum corresponded to the high antioxidant activity of these fruits. Flavanols and anthocyanins may be the main bioactive components in these Cerrado fruits. The daily consumption of at least seven of the twelve Cerrado fruits studied, particularly, araticum, cagaita, lobeira and tucum, may confer protection against oxidative stress, and thus, they may prevent chronic diseases and premature aging. The findings of this study should stimulate demand, consumption and cultivation of Cerrado fruits and result in sustainable development of the region where this biome dominates.

Malanga (Xanthosoma sagittifolium) and Purslane (Portulaca oleracea) Leaves Reduce Oxidative Stress in Vitamin A-Deficient Rats

Aim: This study examined the ability of tropical vegetables to reduce oxidative stress induced by vitamin A deficiency. Methods: Vitamin A-deficient male Wistar rats were divided into four groups which were treated for 30 days with different diets: AIN-93G vitamin A-deficient diet (DD), DD supplemented with pure β-carotene (β-D) and DD supplemented with malanga (Xanthosoma sagittifolium) (MD) or purslane (Portulaca oleracea) (PD) leaves as the only source of vitamin A. The thiobarbituric acid-reactive substances (TBARS), reduced (GSH) and oxidized (GSSG) glutathione, and antioxidant enzyme activities were determined in the heart and liver. Results: The rats fed β-D, MDand PD showed liver and heart TBARS concentrations lower than did DD rats. The liver GSH concentration of β-D, MD and PD rats was lower compared to DD rats. The heart GSSG concentration of the vegetable groups was significantly lower than in DD rats. Liver and heart catalase activities were not significantly different among the groups, nor was heart glutathione peroxidase (GPX) activity, however the β-D rats showed the highest liver GPX activity. There was no difference in liver glutathione-S-transferase level among the groups, while heart activity was higher in rats fed the vegetable leaves. Conclusion: This study evidences that the ingestion of purslane or malanga leaves may have a protective effect against oxidative stress caused by vitamin A deficiency.

Effect of vitamin A deficiency on iron bioavailability.

Background: Vitamin A deficiency alters iron status leading to an iron overload in tissues; however, the mechanism of this interaction is poorly understood. The present study aimed to assess the effect of vitamin A deficiency on iron bioavailability and utilization in rats. Methods: Animals were divided into three groups of six rats each that were fed AIN-93G diet (control group), a vitamin A deficient diet and an iron and vitamin A deficient diet, respectively, for 57 days. The concentrations of hepatic and splenic iron, haemoglobin, red and white cells as well as iron utilization and its bioavailability were evaluated in the three groups. Results: Vitamin A deficiency increased the concentration of red blood cells, haemoglobin concentration (Hb), and splenic iron as well as iron utilization. However, the iron bioavailability observed in vitamin A deficient rats was not significantly different compared to the control group, while in the iron/vitamin A deficient rats, it was higher (p = 0.0056). With regard to iron absorption, no difference was observed among the three groups. Conclusion: Increase of haemoglobin, red blood cells and splenic iron concentration observed in vitamin A deficiency suggests that vitamin A may affect the iron mobilization from tissues rather than iron absorption.

Protein improves the bioavailability of calcium and phosphorus from an alternative dietary supplement in rats

Abstract A mixture of bran cereals, cassava leaf and eggshell powder has been used as an alternative diet supplement to fight malnutrition in low-income communities in Brazil. Due to the high phytic acid content there are some concerns about the bioavailability of nutrients in this mixture (MM). This study investigated the effect of dietary concentrations of protein and NaCl on the bioavailability of MM calcium and phosphorus. Undernourished rats were given deficient diet supplemented with MM, with or without the addition of protein and NaCl. Calcium and phosphorus were found to be bioavailable, since rats fed MM supplemented diet showed higher femur calcium and phosphorus contents than did deficient rats (P