RESUMEN
OBJECTIVE: To evaluate the prevalence of vitamin D deficiency (VDD) and its correlates among apparently healthy children and adolescents. METHODS: We carried out a secondary analysis of data of Comprehensive National Nutrition Survey 2016-18 to analyze the pre-valence and predictors of VDD among Indian children and adolescents. RESULTS: The over-all prevalence of VDD in preschool children (1-4 years), school age (5-9 years) children, and adolescents (10-19 years) was 13.7%, 18.2%, and 23.9%, respectively. Age, living in urban area, and winter season were significantly associated with VDD. Vegetarian diet and high-income households were the main risk factors observed in 5-19 years age category. Female sex and less than three hour of physical activity/week were independent risk factors among adolescents. CONCLUSION: The prevalence and determinants of VDD across different age-groups are reported, and these should be interpreted and addressed to decrease the burden of VDD in India.
Asunto(s)
Deficiencia de Vitamina D , Vitamina D , Preescolar , Humanos , Femenino , Adolescente , Niño , Prevalencia , Deficiencia de Vitamina D/epidemiología , Estado Nutricional , India/epidemiologíaRESUMEN
Adopting sun exposure as a low-cost sustainable strategy in tropical countries needs critical analysis for its feasibility and inclusion in national policy. This review explores the opportunities and challenges associated with sun exposure in tropical countries and discusses potential strategies that may be adopted for promoting sun exposure. For this, two strands of evidence were reviewed; trials on sun exposure, analysed for risk of bias and, the environmental factors that influence acquisition of vitamin D from sun exposure in the context of on-going ecological and nutritional transition. Compilation of data from available databases in terms of deficiency, per cent rural population, status of fortification, air pollution, ultraviolet index, skin reflectance and skin cancer prevalence were done. In the context of environmental and lifestyle-related challenges, opportunities go hand-in-hand in terms of built environment, variability in air pollution and personal factors such as skin pigmentation, precursor availability and general nutritional status. Contextual policy decisions should consider urban and rural development planning, control of air pollution, targeted guidelines for indigenous and immigrant population and use of space technology in educating general population for balanced sun exposure as essential components for a sustainable strategy. Important opportunities exist for tropical countries to develop sun exposure as a strategy for acquiring vitamin D and these need to be explored.
Asunto(s)
Luz Solar , Deficiencia de Vitamina D , Países en Desarrollo , Humanos , Estilo de Vida , Luz Solar/efectos adversos , Vitamina D/uso terapéutico , Deficiencia de Vitamina D/epidemiología , Deficiencia de Vitamina D/prevención & controlRESUMEN
BACKGROUND: Anaemia is a serious public health concern in India. However, national estimates for its prevalence are not available for the 5-14 years age group, nor are estimates available for the types of anaemia among children and adolescents (1-19 years). We aimed to assess the prevalence of anaemia among children and adolescents in India and to categorise types of anaemia on the basis of micronutrient deficiencies. METHODS: We assessed the prevalence of anaemia among children (1-4 years and 5-9 years) and adolescents (10-19 years) using nationally representative data from the Comprehensive National Nutrition Survey. Anaemia was classified on the basis of age and sex-specific WHO cutoffs and serum ferritin, soluble transferrin receptor, folate, cyanocobalamin, and C-reactive protein concentrations as iron deficiency anaemia, folate or vitamin B12 deficiency anaemia, dimorphic anaemia (iron deficiency anaemia and folate or vitamin B12 deficiency anaemia), anaemia of other causes (anaemia not classified as iron deficiency anaemia and folate or vitamin B12 deficiency anaemia), and anaemia of inflammation. FINDINGS: We included 26â765 children (11â624 aged 1-4 yearsâand 15â141 aged 5-9 years) and 14â669 adolescents. In the weighted sample, anaemia prevalence was 40·5% (4553 of 11â233) among 1-4 year-olds, 23·4% (3439 of 14â664) among 5-9 year-olds, and 28·4% (4064 of 14â300) among adolescents. Among 2862 children aged 1-4 years, iron deficiency anaemia (1045 [36·5%]) was the most prevalent type, followed by anaemia of other causes (702 [24·5%]), folate or vitamin B12 deficiency anaemia (542 [18·9%]), dimorphic anaemia (387 [13·5%]), and anaemia of inflammation (186 [6·5%]). Among 2261 children aged 5-9 years, anaemia of other causes was the most common (986 [43·6%]), followed by folate or vitamin B12 deficiency anaemia (558 [24·6%]), iron deficiency anaemia (353 [15·6%]), dimorphic anaemia (242 [10·7%]), and anaemia of inflammation (122 [5·4%]). 861 (31·4%) of 2740 adolescents had anaemia of other causes, 703 (25·6%) had folate or vitamin B12 deficiency anaemia, 584 (21·3%) had iron deficiency anaemia, 498 (18·2%) and dimorphic anaemia, and 94 (3·4%) had anaemia of inflammation. INTERPRETATION: Iron deficiency anaemia is the most common form of anaemia among younger children and anaemia of other causes among 5-9-year-old children and adolescents. Folate or vitamin B12 deficiency anaemia accounts for more than a third of anaemia prevalence. Anaemia prevention efforts should focus on strengthening the existing iron and folate supplementation programmes and prevention of folate or vitamin B12 deficiency anaemia. FUNDING: The Mittal Foundation.
Asunto(s)
Anemia/epidemiología , Adolescente , Niño , Preescolar , Femenino , Deficiencia de Ácido Fólico/epidemiología , Encuestas Epidemiológicas , Humanos , India/epidemiología , Lactante , Masculino , Prevalencia , Deficiencia de Vitamina B 12/epidemiología , Adulto JovenRESUMEN
Plant foods are endowed with micronutrients but an understanding of bioavailability is essential in countries primarily dependent on plant based foods. Bioavailability depends majorly on food synergies. This review examines the nature of certain food synergies and methods to screen and establish it as a strategy to control micronutrient deficiency in the populations. Strong evidence on the synergistic effect of inclusion of vitamin C rich fruits and non-vegetarian foods in enhancing the bioavailability of iron has been demonstrated. Fat is found to be synergistic for vitamin A absorption. Red wine and protein have been explored for zinc absorption and effect of fat has been studied for vitamin D. Methods for screening of bioavailability, and biomarkers to demonstrate the synergistic effects of foods are required. Translation of food synergy as a strategy requires adaptation to the context and popularization of intelligent food synergies.
Asunto(s)
Micronutrientes , Disponibilidad Biológica , Alimentos Fortificados , Hierro , Plantas , Vitamina A , ZincRESUMEN
Paramount among the challenges to our ability to address the role of food and nutrition in health promotion and disease prevention is how to design and implement context-specific interventions and guidance. The Integration to Effective Implementation (I-to-I) concept is intended to address the complexities of the global health context through engagement of the continuum of stakeholders involved in the food and nutrition enterprise. The 2014 Micronutrient Forum (MNF) Global Conference held in Addis Ababa, Ethiopia, in June 2014 offered the opportunity to apply the I-to-I approach with the use of current concerns about the safety and effectiveness of interventions to prevent and treat iron deficiency (ID) as a case study. ID is associated with a range of adverse outcomes, especially in pregnant and nonpregnant women, infants, and primary school-age children. Strategies to combat ID include iron supplementation, multiple micronutrient powders, and food-based interventions to enhance dietary iron intake. Recent reports indicate potential increased adverse risks when iron is provided in areas with high infection burdens (e.g., malaria). This paradox has weakened iron intervention programs. Furthermore, the selection and interpretation of available biomarkers for assessing iron nutrition have been found to be compromised by the inflammatory process. These issues highlight the need for a comprehensive approach that considers basic biology, assessment, interventions, and how these can be translated into appropriate programs and policies. The application of the I-to-I with the use of the MNF offered an opportunity to explore how that might be achieved.
Asunto(s)
Anemia Ferropénica/prevención & control , Estado de Salud , Hierro de la Dieta/uso terapéutico , Hierro/uso terapéutico , Oligoelementos/uso terapéutico , Anemia Ferropénica/complicaciones , Femenino , Salud Global , Humanos , Infecciones/complicaciones , Inflamación/complicaciones , Hierro/efectos adversos , Hierro de la Dieta/efectos adversos , Embarazo , Oligoelementos/efectos adversosRESUMEN
OBJECTIVE: To combine evidence from randomized controlled trials to assess the effect of Fe-fortified foods on mean Hb concentration in children (<10 years). DESIGN: We conducted a meta-analysis of randomized, controlled, Fe-fortified feeding trials that evaluated Hb concentration. The weighted mean difference was calculated for net changes in Hb by using random-effects models. Meta-regression and covariate analyses were performed to explore the influence of confounders on the net pooled effect. SETTING: Trials were identified through a systematic search of PubMed, the Cochrane Library and secondary references. SUBJECTS: Eighteen studies covering 5142 participants were identified. The duration of feeding of fortified foods ranged from 6 to 12 months in these studies. RESULTS: Eighteen studies were included and evaluated in the meta-analysis. The overall pooled estimate of Hb concentration showed a significant increase in the fortification group compared with the control group (weighted mean difference = 5·09 g/l; 95% CI 3·23, 6·95 g/l; I 2 = 90%, τ 2 = 18·37, P < 0·0001). Meta-regression analysis indicated that duration of feeding was positively related to the effect size (regression coefficient = 0·368; 95% CI 0·005, 0·731; P < 0·05). The net pooled effect size after removing the confounders was 4·74 (95% CI 3·08, 6·40) g/l. CONCLUSIONS: We observed an association between intake of Fe-fortified foods and Hb concentration in children aged <10 years. Fe-fortified foods could be an effective strategy for reducing Fe-deficiency anaemia in children.
Asunto(s)
Alimentos Fortificados , Hemoglobinas/análisis , Hierro/metabolismo , Estado Nutricional , Niño , Fenómenos Fisiológicos Nutricionales Infantiles/fisiología , Preescolar , Interpretación Estadística de Datos , Femenino , Hemoglobinas/metabolismo , Humanos , Hierro de la Dieta/administración & dosificación , Masculino , Ensayos Clínicos Controlados Aleatorios como Asunto/estadística & datos numéricosRESUMEN
OBJECTIVE: To develop a psychometrically valid questionnaire for testing knowledge on micronutrients and to assess the relationship between knowledge and biomarkers of micronutrient status among adolescents. DESIGN: Cross-sectional, institution-based, validity and reliability study. SETTING: Seven higher secondary schools were covered in the limits of Greater Hyderabad Municipal Corporation, Hyderabad, India. SUBJECTS: Students aged 15-19 years, n 92 for the pre-test, n 108 for test-retest and n 109 for studying the relationship between knowledge and biomarkers of Fe, retinol, ascorbic acid, α-tocopherol, folic acid and vitamin B12 status. RESULTS: From an item pool of 106, thirty-one items were selected based on content validity. Statistical tools to obtain a valid and reliable questionnaire among adolescent boys and girls resulted in eighteen items with a difficulty index of 0·11-0·86, discrimination index of 0·20-0·72 and validity index (point bi-serial correlation) of 0·10-0·62. Reliability as measured by Cronbach's α was 0·71 and the intra-class correlation coefficient was 0·80. A Bland-Altman plot showed good agreement between test and retest scores. The mean response score to the eighteen-item questionnaire was 5·2 (sd 2·68). The mean values of serum retinol were significantly different (P = 0·022) between groups below (24·8 (sd 6·64) µg/dl) and above (28·0 (sd 7·67) µg/dl) the 50th percentile of knowledge score. The relationship persisted after controlling for economic status as a covariate using analysis of covariance (P = 0·018). Other micronutrients did not show any significant relationship. CONCLUSIONS: A valid and reliable eighteen-item knowledge questionnaire was constructed and found to have a significant positive relationship with plasma retinol status alone.
Asunto(s)
Micronutrientes/administración & dosificación , Estado Nutricional , Psicometría/métodos , Encuestas y Cuestionarios , Adolescente , Ácido Ascórbico/sangre , Biomarcadores/sangre , Estudios Transversales , Femenino , Ácido Fólico/sangre , Conocimientos, Actitudes y Práctica en Salud , Humanos , India , Hierro de la Dieta/sangre , Masculino , Micronutrientes/deficiencia , Instituciones Académicas , Factores Socioeconómicos , Estudiantes , Vitamina A/sangre , Adulto Joven , alfa-Tocoferol/sangreRESUMEN
Iron and zinc have diverse and important physiological functions. Yet, the mechanism of their absorption at the intestine remains controversial and is confounded by the fact that many studies have shown, to varying extents, that they inhibit the absorption of each other. We have studied the expression of iron and zinc transporters and storage proteins, and their regulation, in Caco-2 cells, an established enterocyte model, under normal culture conditions and under conditions of iron and zinc depletion and supplementation using a combination of immunoblotting, confocal microscopy and reverse transcriptase polymerase chain reaction. We show that divalent metal transporter-1 (DMT-1) delocalizes from the plasma membrane upon iron or zinc depletion, but its apical abundance increases with zinc supplementation. This translocation of DMT-1 coincides with an increase in iron uptake upon zinc supplementation, as previously reported by us. FPN-1 expression increases upon zinc supplementation and decreases with iron or zinc depletion, effluxing the excess sequestered iron and thus maintaining cellular iron homeostasis. Zinc influx transporters Zip-1 and Zip-14 and efflux transporters ZnT-1 and ZnT-4 are coordinately regulated under conditions of zinc supplementation and depletion to ensure cellular zinc homeostasis. We have previously reported that iron uptake can entail two transporters and that zinc noncompetitively inhibits iron uptake in Caco-2 cells. We now provide evidence that this inhibition is independent of DMT-1 and that Zip-14 may be a relevant iron transporter. These new observations provide experimental support to this two-transporter model of iron uptake and give mechanistic insight to iron-zinc interactions during uptake at the enterocyte.
Asunto(s)
Proteínas de Transporte de Catión/metabolismo , Enterocitos/metabolismo , Regulación de la Expresión Génica , Hierro/metabolismo , Zinc/metabolismo , Células CACO-2 , Proteínas de Transporte de Catión/genética , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Polaridad Celular , Quelantes/farmacología , Enterocitos/citología , Enterocitos/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Absorción Intestinal/efectos de los fármacos , Hierro de la Dieta/metabolismo , Microscopía Confocal , Transporte de Proteínas/efectos de los fármacos , ARN Mensajero/metabolismoRESUMEN
BACKGROUND & OBJECTIVES: Psychosocial stressors leading to allostatic load need to be explored further as these have great scope for early intervention. Stress studies done in India are mostly based on sources of stress and objective measures of stress. Therefore, the objective of the present study was to assess stress appraisal among students (16-17 yr) and to identify institution-specific differences (Private vs. Government) in stress appraisal and coping. METHODS: The study was carried out among 16-17 yr old apparently normal students. Eighty students were recruited from six schools ensuring equal representation from gender/category of schools (Government/Private). Validated and culturally adaptable behavioural scales for perceived stress (PSS), stressful life events (LES) and coping were administered. Psychological morbidity was assessed using GHQ-12. Data on 75 students were available for statistical analysis. RESULTS: The students of both Government and Private schools showed similar stress perception, though the former tend to have a higher mean score. The scores were significantly higher on avoidance coping (P<0.05). The stepwise regression model showed coping as the independent predictor of perceived stress (R2 = 10%). INTERPRETATION & CONCLUSIONS: Students from Government schools had significantly higher scores on avoidance coping and therefore, suitable for a systematic study on chronic stress for early intervention.
Asunto(s)
Adaptación Psicológica , Acontecimientos que Cambian la Vida , Estrés Psicológico/epidemiología , Estrés Psicológico/psicología , Estudiantes/psicología , Adolescente , Femenino , Humanos , India , Masculino , Percepción , Proyectos PilotoRESUMEN
Iron and zinc deficiencies are the most prevalent nutrient deficiencies worldwide. They often coexist as the dietary factors, especially phytate, which impairs iron absorption also affects zinc absorption. Therefore, suitable strategies are required to control multiple micronutrient deficiencies in populations that subsist on high-phytate foods such as the whole wheat flour based Indian bread (chapatti). The objective of the study, therefore, was to test the bioavailability of iron and zinc in 2 multiple micronutrient beverage premixes in the absence and presence of chapatti. The premix-1 contained iron, zinc, and vitamin A while premix-2 contained all micronutrients in premix-1, plus folic acid and ascorbic acid. Ferritin induction and (65)Zn uptake were assessed using coupled in vitro digestion/Caco-2 cell line model as the surrogate markers of iron and zinc bioavailability, respectively. The results show that iron bioavailability from premixes-1 and 2 was similar in the absence of chapatti. However, premix-2 showed significantly higher iron bioavailability compared to premix-1 in the presence of chapatti. In contrast, the zinc uptake was similar from both premixes-1 and 2 in the absence or presence of chapatti. These results suggest that both the premixes provide bioavailable minerals, but premix-2 appears to be promising in the presence of foods that have high phytate.
Asunto(s)
Bebidas/análisis , Alimentos Fortificados , Hierro de la Dieta/farmacocinética , Zinc/farmacocinética , Ácido Ascórbico/farmacocinética , Disponibilidad Biológica , Pan/análisis , Células CACO-2 , Ferritinas/metabolismo , Ácido Fólico/farmacocinética , Humanos , Micronutrientes/farmacocinética , Ácido Fítico/farmacocinética , Triticum/metabolismo , Vitamina A/farmacocinéticaRESUMEN
A community based cross-sectional study was carried out in rural areas of West Bengal with the aim to assess the prevalence of vitamin A deficiency (VAD) among rural preschool children. Clinical examination was carried out on 9,228 children for the signs and symptoms of VAD and a sub-sample of 590 children were covered for the estimation of blood vitamin A levels using dried blood spot (DBS) method. The prevalence of Bitot's spots was 0.6% (95% CI=0.44, 0.76), which is more than the public health significance, and it increased with increase in age. The prevalence was significantly higher (P<0.001) among boys (0.8%) as compared to girls (0.4%). The proportion of children with subclinical vitamin A deficiency (blood vitamin A < 20 ug/dL) was 61% (95% CI: 52.3-65.1), and it was significantly (P<0.01) higher among the children of lower socioeconomic communities.
Asunto(s)
Población Rural/estadística & datos numéricos , Deficiencia de Vitamina A/epidemiología , Preescolar , Estudios Transversales , Femenino , Humanos , India/epidemiología , Lactante , Masculino , Factores SocioeconómicosRESUMEN
BACKGROUND: Vitamin A deficiency (VAD) continues to be a major public health nutritional problem in India, even though the National Vitamin A Prophylaxis Programme has been in operation for more than three decades. AIM: To assess the prevalence of vitamin A deficiency among rural pre-school children. SUBJECTS AND METHODS: A community-based cross-sectional study was carried out in rural Madhya Pradesh. A total of 8777 pre-school children were clinically examined for VAD and blood vitamin A levels were estimated in a sub-sample by dried blood spot method. RESULTS: Prevalence of night blindness and Bitot's spot, an objective sign of VAD, was 0.8% and 1.4%, respectively, and prevalence increased significantly (p < 0.001) with age. The proportion of children with blood vitamin A deficiency ( < 20 µg/dL) was 88% (95% CI: 84.8-91.2).The prevalence of Bitot's spot was significantly (p < 0.001) higher among children of lower socio-economic communities, 3-5-year age group and those of illiterate mothers. CONCLUSIONS: VAD is a major public health problem among rural children of Madhya Pradesh. Children of 3-5 years and those belonging to lower socio-economic communities are at high risk of VAD. Therefore, appropriate intervention measures are to be initiated to improve the vitamin A status of children.
Asunto(s)
Salud Rural , Deficiencia de Vitamina A/epidemiología , Vitamina A/sangre , Preescolar , Estudios Transversales , Femenino , Educación en Salud , Humanos , India/epidemiología , Lactante , Masculino , Programas Nacionales de Salud , Ceguera Nocturna/sangre , Ceguera Nocturna/tratamiento farmacológico , Ceguera Nocturna/epidemiología , Encuestas Nutricionales , Prevalencia , Factores Socioeconómicos , Deficiencia de Vitamina A/sangre , Deficiencia de Vitamina A/tratamiento farmacológico , Deficiencia de Vitamina A/prevención & controlRESUMEN
We are maintaining two obese mutant rat strains (WNIN/Ob and WNIN/GR-Ob) in our animal facility since 1997. These rat colonies are perpetuated by crossing heterozygous littermates, since the obese phenotypes of both genders turned out be infertile. The present study revealed the reasons for this infertility. The male obese rats, though appeared normal in terms of sperm count, sperm motility and testis histology, however found wanting in terms of libido. This appeared to be due to low circulating testosterone levels seen in these animals, which should also account for low testis and accessory gland weights seen in them. The females exhibited delayed puberty, in terms of days taken for opening of vagina, irregular oestrus cycles and had small ovaries and short and stumpy uterine horns. The FSH peak observed in control lean animals during oestrus stage of the sexual cycle and also the E2 peak of normal oestrus cycle was conspicuously absent in these animals. They also showed elevated levels of progesterone throughout the sexual cycle. Thus the infertility seen in these mutants could be attributed to their abnormal gonadosteroid levels and the resulting anatomical and physiological defects.
RESUMEN
The effect of red wine (RW), red grape juice (RGJ), green tea (GT), and representative polyphenols on Caco-2 cell (65)Zn uptake was explored. RW, RGJ, and GT enhanced the uptake of zinc from rice matrix. Fractionation of RW revealed that enhancing activity of zinc uptake was exclusively resided in the polyphenol fraction. Among the polyphenols tested, only tannic acid and quercitin stimulated the uptake of zinc while others did not influence the uptake. In tune with these results, only tannic acid and quercitin competed with zinquin (a zinc selective fluorophore) for zinc in vitro. Although all the polyphenols tested appear to enhance the expression of metallothionein (MT), the induction was higher with tannic acid, quercitin, and RW extract. Furthermore, phytic acid abrogated the tannic acid-induced MT expression. These results suggest that polyphenol-rich beverages, tannic acid, and quercitin bind and stimulate the zinc uptake and MT expression in Caco-2 cells.
Asunto(s)
Absorción/efectos de los fármacos , Bebidas/análisis , Flavonoides/análisis , Flavonoides/farmacología , Metalotioneína/metabolismo , Fenoles/análisis , Fenoles/farmacología , Regulación hacia Arriba/efectos de los fármacos , Zinc/farmacocinética , Unión Competitiva , Células CACO-2 , Quelantes/química , Digestión , Flavonoides/química , Flavonoides/aislamiento & purificación , Frutas/química , Humanos , Oryza/química , Oryza/metabolismo , Fenoles/química , Fenoles/aislamiento & purificación , Ácido Fítico/análisis , Ácido Fítico/farmacología , Polifenoles , Quercetina/química , Quercetina/farmacología , Quinolonas/química , Semillas/química , Semillas/metabolismo , Taninos/análisis , Taninos/antagonistas & inhibidores , Taninos/química , Taninos/farmacología , Té/química , Compuestos de Tosilo/química , Vitis/química , Vino/análisis , Zinc/análisis , Zinc/química , Radioisótopos de Zinc/farmacocinéticaRESUMEN
Studies in humans and animals have suggested negative interactions of iron and zinc during their intestinal absorption. Further, zinc seems to prevent iron-induced oxidative damage in rats, which was hypothesized to be through the modulation of the intracellular iron signaling pathway. The aim of this study was, therefore, to understand the effects of zinc on oxidant-induced iron signaling and cell death in human enterocyte-like Caco-2 cells. We demonstrate that zinc decreases glucose/glucose oxidase (H(2)O(2)-generating system)-induced iron uptake and inhibits iron-regulatory protein 1 activation and divalent metal ion transporter 1 expression. There was also a concomitant decrease in oxidant-induced intracellular labile iron and restoration of ferritin and metallothionein expression. Further, zinc enhanced the Bcl-2/Bax ratio and reduced caspase-3 activity, leading to inhibition of apoptosis. Interestingly, bathophenanthroline disulfonic acid, an extracellular iron chelator, emulated the effects of zinc except for the reduced ferritin levels. These results suggest that zinc inhibits apoptosis by reducing oxidant-induced iron signaling in Caco-2 cells.
Asunto(s)
Apoptosis/efectos de los fármacos , Enterocitos/metabolismo , Transducción de Señal/efectos de los fármacos , Zinc/metabolismo , Células CACO-2 , Caspasa 3/metabolismo , Proteínas de Transporte de Catión/biosíntesis , Proteínas de Transporte de Catión/genética , Quelantes/farmacología , Enterocitos/efectos de los fármacos , Enterocitos/patología , Ferritinas/biosíntesis , Ferritinas/genética , Humanos , Absorción Intestinal , Hierro/metabolismo , Proteínas Reguladoras del Hierro/genética , Proteínas Reguladoras del Hierro/metabolismo , Metalotioneína/biosíntesis , Metalotioneína/genética , Estrés Oxidativo/efectos de los fármacos , Fenantrolinas/farmacología , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Proteína X Asociada a bcl-2/metabolismoRESUMEN
Iron and zinc interact at the enterocyte and influence the absorption of one another. We have previously reported that zinc noncompetitively inhibits iron uptake in Caco-2 cells, a widely accepted model of the absorptive enterocyte. However, the determinants of this interaction, such as the effect of dietary ligands, remain uncharacterized. Dietary ligands selectively chelate iron and zinc in definite stoichiometric proportions and thus alter the bioavailability from food matrices. Here, we have used common dietary ligands, such as ascorbic acid, phytic acid, tannic acid, tartaric acid, cysteine, histidine, and methionine to characterize iron, zinc uptake individually and in combination, using Caco-2 cells. Selective chelation of zinc, using cysteine, decreased the magnitude of inhibition of iron uptake but could not reverse the inhibition. On the other hand, selective increase in iron uptake in the presence of methionine resulted in increased zinc uptake, rather than inhibition. Taken together, these in vitro results suggest that dietary ligands can modulate iron-zinc interaction and that zinc cannot competitively inhibit iron uptake.
Asunto(s)
Dieta , Enterocitos/metabolismo , Absorción Intestinal , Hierro/metabolismo , Zinc/metabolismo , Aminoácidos/metabolismo , Transporte Biológico , Células CACO-2 , Ácidos Carboxílicos/metabolismo , Quelantes/metabolismo , Humanos , Radioisótopos de Hierro , Ligandos , Ácido Fítico/metabolismo , Taninos/metabolismo , Radioisótopos de ZincRESUMEN
Iron and zinc interact at the enterocyte during absorption, but the mechanism(s) remain elusive. The aim was, therefore, to understand the mechanism of interaction using kinetic analyses of iron and zinc uptake, individually and in combination under normal and altered cellular mineral concentrations in human intestinal Caco-2 cell line. Striking differences in kinetic parameters were observed between iron and zinc uptake. Iron uptake followed a two-component model, while zinc uptake followed a three-component model. Iron uptake had a Km of 3.6 microM and Vmax of 452 pmol/mg protein/min, while zinc uptake had a Km of 42 microM and Vmax of 3.09 pmol/mg protein/min. Zinc dose-dependently inhibited iron uptake through mixed-inhibition but iron marginally increased zinc uptake. Cellular zinc repletion doubled iron uptake and eliminated inhibition, but zinc depletion decreased iron uptake. Iron pre-treatment had no effect on zinc uptake. Based on these results, a two-transporter model of iron uptake, comprising the apical iron uptake transporter divalent metal ion transporter-1 (DMT-1) and an unknown putative transporter was derived. This model for DMT-1 was verified by immunoblotting. These results implied that cellular zinc status profoundly influenced iron uptake and its interactions with zinc during uptake. DMT-1 might not simultaneously transport iron and zinc, providing a mechanistic basis for observed interactions.
Asunto(s)
Regulación de la Expresión Génica , Mucosa Intestinal/metabolismo , Hierro/química , Zinc/química , Animales , Transporte Biológico , Células CACO-2 , Proteínas de Transporte de Catión/metabolismo , Relación Dosis-Respuesta a Droga , Enterocitos/metabolismo , Humanos , Absorción Intestinal , Cinética , Modelos Biológicos , RatasRESUMEN
Repeated surveys have shown that the magnitude of nutritional anaemia is of public health concern in India. Though reduced intake of iron is a major aetiological factor, low intake or an imbalance in the consumption of other haematopoietic nutrients, their utilization; increased nutrient loss and/or demand also contribute to nutritional anaemia. In India, cereals and millets form the bulk of the dietaries and are major sources of non-haeme iron. According to the current estimates, the intake of iron is less than 50 per cent of the recommended dietary allowance (RDA) and iron density is about 8.5 mg/1000 Kcal. It is now well established that iron bioavailability from habitual Indian diets is low due to high phytate and low ascorbic acid/iron ratios. These factors determine iron bioavailability and the RDA. There are striking differences in the iron RDAs among the physiological groups, which need to be validated. The other dietary factors affecting iron status are inadequate intake of folic acid and vitamins B(12), A, C and other vitamins of the B-complex group. Chronic low grade inflammation and infections, and malaria also contribute significantly to iron malnutrition. Recent evidence of the interaction of hepcidin (iron hormone) and inflammatory stimuli on iron metabolism has opened new avenues to target iron deficiency anaemia. Food-based approaches to increase the intake of iron and other haematopoietic nutrients through dietary diversification and provision of hygienic environment are important sustainable strategies for correction of iron deficiency anaemia.
Asunto(s)
Hierro de la Dieta/administración & dosificación , Hierro de la Dieta/farmacocinética , Hierro/metabolismo , Adolescente , Adulto , Anemia Ferropénica/dietoterapia , Anemia Ferropénica/epidemiología , Anemia Ferropénica/prevención & control , Disponibilidad Biológica , Femenino , Humanos , India/epidemiología , Lactante , Inflamación/metabolismo , Masculino , Política Nutricional , Necesidades Nutricionales , Estado Nutricional , Estrés Oxidativo , EmbarazoRESUMEN
The kinetics, depletion/repletion of zinc, and effects of dietary ligands/food matrices on (65)Zn uptake was studied in Caco-2 cells. The uptake of zinc showed a saturable and nonsaturable component, depending upon the media zinc concentrations. Intracellular depletion increased zinc uptake, whereas zinc loading did not. Phytic acid and histidine inhibited zinc uptake, while tannic acid, tartaric acid, arginine, and methionine increased zinc uptake. Tannic acid at a 1:50 molar ratio promoted zinc uptake from wheat- and rice-based food matrices. Further, Caco-2 cells responded similarly with zinc and iron uptake when fed Indian bread prepared from low- and high-extraction wheat flour, representing low and high phytate content. However, inclusion of tea extract or red grape juice as a source of polyphenols enhanced the uptake of zinc while decreasing that of iron. These results suggest that the Caco-2 cells predict the correct direction of response to dietary ligands even from complex foods.