Body Composition in Youths Aged 10‒17 Years by Deuterium Oxide Dilution, Air Displacement Plethysmography, and DXA: Validation of the Medical Body Composition Analyzer Bioimpedance Device by a 4-Compartment Model.

BACKGROUND: The medical body composition analyzer (mBCA) incorporates advances in multifrequency technology and has been validated using a 4-compartment (4C) model in adults but not in youths aged <18 y. OBJECTIVES: This study aimed to formulate a 4C model based on 3 reference methods and develop and validate a body composition prediction equation for the mBCA in youths aged 10‒17 y. METHODS: The body density of 60 female and male youths was measured by air displacement plethysmography, total body water by deuterium oxide dilution, and BMC by DXA. Data from the equation group (n = 30) were used to formulate a 4C model. The all-possible-regressions method was used to select variables. The model was validated in a second cohort (n = 30) in a random split design. The accuracy, precision, and potential bias were evaluated by the Bland and Altman procedure. RESULTS: Mean age, weight (W), height (H), waist circumference, and z-score of BMI were 13.6 ± 2.3 y, 54.5 ± 15.5 kg, 156 ± 11.9 cm, 75.5 ± 10.9 cm, and 0.70 ± 1.32 z, respectively. The prediction equation was as follows: FFM in kg (FFMkg) = ([0.2081] ∗ [W] + [0.8814] ∗ [H2cm/RΩ] + [0.2055 ∗ XcΩ])-15.343; R2 = 0.96; standardized root-mean-square error (SRMSE) = 2.18 kg. FFM did not differ between the 4C method (38.9 ± 12.0 kg) and the mBCA (38.4 ± 11.4 kg) (P > 0.05). The relationship between these 2 variables did not deviate from the identity line, was not significantly different from 0, and the slope was not significantly different from 1.0. In the precision prediction model of mBCA, the R2 value was 0.98 and SRMSE was 2.1. No significant bias was found when regressing differences between methods and their means (P = 0.08). CONCLUSIONS: The equation for the mBCA was accurate, precise, had no significant bias, had substantial strength of agreement and could be used in this age group when subjects were preferentially within the constraints of a specified body size.

External validation of a prediction model for estimating fat mass in children and adolescents in 19 countries: individual participant data meta-analysis.

OBJECTIVE: To evaluate the performance of a UK based prediction model for estimating fat-free mass (and indirectly fat mass) in children and adolescents in non-UK settings. DESIGN: Individual participant data meta-analysis. SETTING: 19 countries. PARTICIPANTS: 5693 children and adolescents (49.7% boys) aged 4 to 15 years with complete data on the predictors included in the UK based model (weight, height, age, sex, and ethnicity) and on the independently assessed outcome measure (fat-free mass determined by deuterium dilution assessment). MAIN OUTCOME MEASURES: The outcome of the UK based prediction model was natural log transformed fat-free mass (lnFFM). Predictive performance statistics of R2, calibration slope, calibration-in-the-large, and root mean square error were assessed in each of the 19 countries and then pooled through random effects meta-analysis. Calibration plots were also derived for each country, including flexible calibration curves. RESULTS: The model showed good predictive ability in non-UK populations of children and adolescents, providing R2 values of >75% in all countries and >90% in 11 of the 19 countries, and with good calibration (ie, agreement) of observed and predicted values. Root mean square error values (on fat-free mass scale) were <4 kg in 17 of the 19 settings. Pooled values (95% confidence intervals) of R2, calibration slope, and calibration-in-the-large were 88.7% (85.9% to 91.4%), 0.98 (0.97 to 1.00), and 0.01 (-0.02 to 0.04), respectively. Heterogeneity was evident in the R2 and calibration-in-the-large values across settings, but not in the calibration slope. Model performance did not vary markedly between boys and girls, age, ethnicity, and national income groups. To further improve the accuracy of the predictions, the model equation was recalibrated for the intercept in each setting so that country specific equations are available for future use. CONCLUSION: The UK based prediction model, which is based on readily available measures, provides predictions of childhood fat-free mass, and hence fat mass, in a range of non-UK settings that explain a large proportion of the variability in observed fat-free mass, and exhibit good calibration performance, especially after recalibration of the intercept for each population. The model demonstrates good generalisability in both low-middle income and high income populations of healthy children and adolescents aged 4-15 years.

[Impact of fortified milk on the iron and zinc levels in Mexican preschool children]. / Efecto de la leche fortificada liconsa en el estado de hierro y zinc en prescolares Mexicanos.

The aim of this study was to assess the efficacy of a national program of consumption of fortified milk "Liconsa" on the nutritional status of iron and zinc in pre-school children (3-5 y). The study was conducted in 77 healthy children of both genders. 54 of them consumed Liconsa fortified milk (GCLFL) and 23 consumed no fortified milk (GR). Iron status was determined by measuring hemoglobin and ferritin and zinc status by serum zinc. The consumption of milk was on free demand and it was estimated at baseline and 6 mo after. Through 24-h recall of measured consumption of iron and zinc in the total diet. Descriptive statistics, Student's t test for independent samples and chi-square test for differences in proportions. Children who consumed fortified milk showed an increase of hemoglobin and ferritin levels [1.13 g/dL (p < 0.05) and 5.83 µg/L (p < 0.05) respectively]. Additionally, a decrease was found of the prevalence of low iron stores from 20.4 to 4.1% (p < 0.05). The serum zinc level showed an increase of 45.2 µg/dL (p < 0.05). At the end of the study no child showed a micronutrient deficiency. Children who did not consume fortified milk Liconsa showed no significant change in their serum iron and zinc values. The average consumption of milk powder Liconsa was 22.7 ± 14.5 g, providing 2.5 mg of daily iron and zinc. Supplied diet 9.2 ± 3.4 mg of iron and 6.9 ± 3 mg of zinc. The consumption of fortified milk had a beneficial effect on the serum levels of iron and zinc in children's social welfare program Liconsa.

Introducción: Existen programas que buscan mejorar el estado nutricio de la población vulnerable mediante la fortificación de alimentos. En México, el programa de leche fortificada Liconsa está dirigido a familias de bajo nivel socioeconómico. Objetivo: Evaluar el efecto del consumo de leche fortificada Liconsa en el estado de nutrición de hierro y zinc, en preescolares. Sujetos y métodos: Estudio cuasiexperimental, conducido en colonias marginadas de Hermosillo, México. Participaron 77 niños sanos, de los cuales 54 consumieron leche fortificada Liconsa (GCLFL) y 23 conformaron el grupo de referencia (GR, consumo de leche fluida de vaca, no fortificada). El estado de hierro se midió a través de hemoglobina, ferritina, hierro sérico, capacidad total de fijación de hierro, saturación de transferrina; y zinc sérico. También se estimó el consumo de leche fortificada a libre demanda, en la etapa basal y después de 6 meses. Mediante dos recordatorios de 24 horas, no consecutivos, se midió el consumo de hierro y zinc en la dieta total. Se realizó estadística descriptiva, prueba t-student para muestras independientes y prueba de ji cuadrada para diferencias de proporciones. Resultados: Los niños que consumieron leche fortificada incrementaron sus niveles de hemoglobina (1,13 g/dL, p < 0,05) y ferritina (5,83 µg/L, p < 0,05). La prevalencia de bajas reservas de hierro disminuyó de 20,4% a 4,1% (p < 0,05) y el zinc sérico aumentó en 45,2 µg/dL (p < 0,05). En el grupo de referencia, no hubo cambios significativos. El promedio diario del consumo de leche fortificada Liconsa fue de 22,7 ± 14,5 g, que suministró 2,5 mg/d de hierro y zinc. La dieta aportó 9,2 ± 3,4 mg/d de hierro y 6,9 ± 3 mg/d de zinc. Conclusiones: El consumo de leche fortificada beneficia el estado bioquímico de hierro y zinc en los niños del programa de abasto social de Liconsa.

Lifestyle intervention in primary care settings improves obesity parameters among Mexican youth.

Intervention studies in youth with obesity that can be translated into primary care are limited. We compared a lifestyle intervention to a brief intervention applied by primary care physicians (control group) for treating pediatric obesity in the primary care setting. Seventy-six youth with obesity (body mass index [BMI] >95th percentile or >90th percentile plus waist circumference >90th percentile, aged 9 to 17 years) participated in a 12-month, randomized, controlled trial, conducted at a primary care unit in Northern México from June 2006 through October 2007. Participants randomized to lifestyle intervention attended a family-centered program consisting of 12 sessions of behavioral curriculum, dietary advice from a registered dietitian (weekly for the first 3 months and monthly thereafter), and monthly consultations with a primary care physician. Control group participants attended monthly consultations with a primary care physician who received a brief training on obesity. Forty-three (57%) participants completed the 12 months of study. After 12 months, mean changes (95% confidence interval) in body weight for the lifestyle group and the control group were -0.8 kg (-3.2, 1.5) vs +5.6 kg (3, 8.2; P<0.001) and mean changes in BMI were -1.8 (-2.6, -0.9) vs +0.4 (-0.5, 1.3; P<0.001), respectively. Intention-to-treat analysis at 12 months confirmed significant differences in primary outcomes (weight -3.5 kg, P=0.02; BMI -1.2, P=0.03) in favor of the lifestyle group. This study provides preliminary evidence that primary care physicians supported by a registered dietitian and a behavioral curriculum can be a successful strategy for treating pediatric obesity in the primary care setting.

Efecto de la suplementación con una dosis masiva de vitamina A en niños de 6 a 36 meses de edad / Effect of massive vitamin A supplement in children from 6 to 36 months of age

Objetivo. Evaluar el impacto de la suplementación con una dosis masiva de vitamina A en el estado nutricio de dicha vitamina y del hierro, en niños de zonas urbanas marginadas de Hermosillo, Sonora, México. Material y métodos. Se seleccionaron 60 niños (6-36 meses), a los que se les administró una dosis de 100 00 UI (6-12 meses) y 200 000 UI (12-36 meses) de vitamina A en el Día Nacional de Salud de la Secretaría de Salud (junio de 1994). Se midieron niveles séricos de retinol, carotenioide, hierro, transferrina y ferritina, en tres fases: basal, a las dos semanas y después de tres meses. Resultados. En la primera fase, la mediana de retinol fue 0.7 µmol/l; en la segunda aumentó a 0.97 µmol/l (p< 0.001), y en la tercera disminuyó a 0.83 µmol/l (p> 0.05). Un 6.3 por ciento de los niños presentó deficiencia severa de vitamina A al inicio, y no se encontró ningún caso en las fases posteriores a la suplementación. En la fase basal, 42 por ciento de los casos presentaron deficiencia moderada y la mayoría fue normal en las siguientes fases. No hubo diferencias en los niveles de hierro y transferrina (p> 0.05), pero sí en ferritina (p< 0.001), lo que indica un mejoramiento en las reservas de hierro a los tres meses. Conclusiones. Las campañas de distribución de dosis masivas pueden tener un impacto importante en el estado nutricio de vitamina A y hierro