Biomedical subjects

Tomás Walter

Publications and source records attributed to Tomás Walter.

3 recordsLinked to original sources

PubMed2006

Iron deficiency in infancy: applying a physiologic framework for prediction.

BACKGROUND: Infants aged 6-24 mo are at high risk of iron deficiency. Numerous studies worldwide have sought to identify predictors of iron deficiency in this age group. OBJECTIVE: The objectives of the study were to apply a physiologic model to identify risk factors for iron deficiency and to consider those risk factors under different conditions of iron supplementation. We predicted that factors related to iron status at birth (lower gestational age and lower birth weight), postnatal needs for iron (more rapid growth), and bioavailable iron (more cow milk) would be major risk factors. DESIGN: The physiologic framework was assessed in 1657 Chilean infants (aged 12 mo) with birth weights >or=3 kg who were randomly assigned at age 6 mo to high or low iron supplementation or no added iron. Based on venous blood, the analysis used mean corpuscular volume and concentrations of hemoglobin, free erythrocyte protoporphyrin, and ferritin. Logistic regression models were used to identify predictors of iron deficiency anemia and iron deficiency without anemia. RESULTS: The prevalence of iron deficiency (>or=2 abnormal iron measures) was 34.9% at age 12 mo. Of 186 infants with hemoglobin concentrations <110 g/L, 158 (84.9%) were iron deficient. The only consistent (and the strongest) predictor of iron deficiency or iron deficiency anemia was lower 6-mo hemoglobin. Factors related to poorer iron status at birth (lower birth weight, shorter gestation though full-term, or both) were predictors in the no-added-iron and high-iron groups. Otherwise, predictors varied by iron supplementation. CONCLUSION: Variations in predictors of iron deficiency or iron deficiency anemia according to iron supplementation suggest that direct comparisons across studies are tenuous at best without data on early iron status and certainty that specific conditions are comparable.

Anemia, Iron-Deficiency↗

PubMed2004

Rapid drop in infant blood lead levels during the transition to unleaded gasoline use in Santiago, Chile.

This study was conducted to relate blood lead levels in infants to changes in lead emissions in Santiago, Chile, a heavily polluted setting where leaded gasoline began to be replaced with unleaded gasoline in 1993. Over an 18-mo period, 422 infants had blood lead levels, cotinine, and iron status determined at 12 mo. Blood lead levels fell at an average rate of 0.5 microg/dl every 2 mo, from 8.3 to 5.9 microg/dl, as the city experienced a net fall of 30% in the quantity of leaded gasoline sold. Time progression, car ownership, serum cotinine, and type of housing were significantly associated with a blood lead level > or = 10 microg/dl. In this study, the authors demonstrated that infant blood lead levels, even if relatively low, can drop very rapidly in conjunction with decreases in environmental lead exposure.

Carcinogens↗

PubMed2003

Iron bioavailability in corn-masa tortillas is improved by the addition of disodium EDTA.

Corn-masa flour flat bread tortillas are the main staple of Mexican and Central American populations. Due to high concentrations of inhibitors of iron absorption, the bioavailability from this matrix is unknown. We wanted to determine the most suitable fortificant that would efficaciously improve iron bioavailability. In tortillas prepared with commercial precooked, lime-treated, corn-masa flour, we examined the in vitro solubility of the following forms of iron: native iron with and without Na2EDTA, elemental reduced iron plus Na2EDTA, ferrous fumarate with and without Na2EDTA, bisglycine iron, ferrous sulfate and NaFeEDTA. We also examined the in vivo bioavailability in humans with double radioiron erythrocyte incorporation of ferrous fumarate with and without Na2EDTA, bisglycine iron, NaFeEDTA and native iron plus Na2EDTA, beans and rice. In vitro, solubility ranged from 1% in iron forms without Na2EDTA to 19.4% for NaFeEDTA. Forms of iron with Na2EDTA had intermediate values. In vivo radioiron studies showed that iron forms without Na2EDTA also had low bioavailability (< or =1%). NaFeEDTA had the highest bioavailability (5.3%). The bioavailability of all iron forms improved significantly when tested with Na2EDTA (<0.05). Adding Na2EDTA to ferrous fumarate increased bioavailability from 0.87% to 2.9% (P < 0.001). We conclude that NaFeEDTA is the form of iron best absorbed, but alternatively, ferrous fumarate plus Na2EDTA comprises a feasible option as a fortificant.

Adult↗