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.