Abstract Long-chain polyunsaturated fatty acids (LC-PUFAs) are critical for infant growth and development, particularly arachidonic acid (ARA, C20:4n-6) and docosahexaenoic acid (DHA, C22:6n-3). ARA and DHA are components of cell membrane phospholipids and play an important role in cell division, differentiation, and signaling; and DHA is the n-3 fatty acid predominant in the developing brain and retina. During the third trimester of pregnancy, LC-PUFAs increase substantially in fetal circulation, and a “biomagnification” process in the fetal brain is observed. Moreover, LC-PUFAs are precursors of eicosanoids and metabolites, which modulate the intensity and duration of the immune response. LC-PUFA synthesis implies complex desaturation and elongation processes on their principal precursors, linoleic acid (LA) (18:3 n-6) (series n-6) and α-linolenic acid (LNA) (20:3 n-3) (series n-3), where fatty acid desaturases (FADS) and elongases (ELOVL) are competing. It is important to notice that during the first months of life, as a consequence of low enzymatic activity, LC-PUFA synthesis from LA and LNA is reduced, especially in those infants carrying variations in the FADS and ELOVL genes, which are involved in LC-PUFA synthesis, and so they are unable to supply their own DHA and ARA needs. Homozygote infants for FADS haplotype A (97 % of the Latinoamerican population) show low levels of ARA (only 43 %) and DHA (only 24 %) when compared to those carrying haplotype D (more prevalent in Europe, Africa and Asia). Human milk is the only source of LA, LNA, ARA, and DHA for the neonate and infant till complementary feeding (CF) is introduced. Infants fed with infant formulas must receive enough amounts of LA, LNA, ARA, and DHA to cover their nutritional requirements. The new guidelines by the European Food Safety Authority (EFSA) (2016) recommend that infant formulas and follow-on formulas must contain 20-50 mg of DHA/100 kcal (0.5-1 % of total fatty acids, which is higher than in human milk and the majority of infant formulas in the market), and it is not necessary to add ARA. This new regulation, which is already applicable since February 2020, has resulted in profound controversy because there is no scientific evidence about its appropriateness and safety for healthy children. Then, different international expert groups have revised the research already published about the effects of ARA and DHA addition to infant formulas, and discussed different emerging questions from this European directive. The expert group led from the University of Granada (Spain) recommends the addition of ARA in similar or higher concentrations than those of DHA, at least equal to those present in human milk (0.3 % of total fatty acids), although preferably 0.5 % and up to around 0.64 % of total fatty acids, since new studies confirm the optimal intake of ARA and DHA during the different developmental stages. This recommendation could be of particular importance for infants carrying the haplotype A of FADS.

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RESUMO Objetivos. O Report Card de 2018 para o México avalia as oportunidades disponíveis para que crianças e jovens mexicanos atinjam níveis adequados de atividade física, sono e comportamento sedentário. Métodos. O Report Card é um sistema de vigilância que reúne dados de pesquisas nacionais, censos, documentos governamentais, websites, literatura cinzenta e estudos publicados para avaliar 16 indicadores em quatro categorias: Comportamentos Diários, Forma Física, Ambientes e Influências, e Estratégias e Investimentos. Os dados foram comparados com indicadores de referência estabelecidos. A cada indicador foi atribuída uma pontuação de 1 a 10 (pontuações abaixo de 6 indicam reprovação) ou "incompleta" se os dados fossem insuficientes/indisponíveis. Resultados. As pontuações para o Comportamento Diário foram as seguintes: atividade física geral: 4; participação em esportes organizados: 5; brincadeiras ativas: 3; transporte ativo: 5; sono: 7; comportamento sedentário: 3. A pontuação para a Forma Física foi de 7. As pontuações para Ambientes e Influências foram: família e amigos, incompleta; escola: 3; comunidade e ambiente: 4. As pontuações para Estratégias e Investimentos foram: estratégias governamentais: 6; organizações não-governamentais: 2. Conclusão. As pontuações baixas em 11 dos 16 indicadores indicam que as escolas, famílias, comunidades e o governo precisam trabalhar juntos para oferecer mais oportunidades de atividade física às crianças e jovens no México.

ABSTRACT Objectives. Mexico’s 2018 Report Card evaluates the opportunities available for Mexican children and youth to reach healthy levels of physical activity, sleep, and sedentary behavior. Methods. The Report Card is a surveillance system that gathers data from national surveys, censuses, government documents, websites, grey literature, and published studies to evaluate 16 indicators in four categories: Daily Behaviors; Physical Fitness; Settings and Sources of Influence; and Strategies and Investments. Data were compared to established benchmarks. Each indicator was assigned a grade from 1 – 10 (< 6 is a failing grade) or “incomplete” if data was insufficient/unavailable. Results. Daily Behavior grades were: Overall Physical Activity, 4; Organized Sport Participation, 5; Active Play, 3; Active Transportation, 5; Sleep, 7; and Sedentary Behavior, 3. Physical Fitness, received a 7. Settings and Sources of Influence grades were: Family and Peers, incomplete; School, 3; and Community and Environment, 4. Strategies and Investments were: Government Strategies, 6; and Non-Government Organizations, 2. Conclusion. Low grades in 11 of the 16 indicators indicate that schools, families, communities, and government need to work together to improve physical activity opportunities for children and youth in Mexico.

RESUMEN Objetivos. El boletín de notas de México correspondiente al 2018 evalúa las oportunidades a disposición de la población infantil y joven mexicana para que puedan desarrollar niveles adecuados de actividad física y sueño, y disminuyan el sedentarismo. Métodos. El boletín es un sistema de vigilancia que recopila los datos obtenidos en las encuestas nacionales, censos, documentos gubernamentales, sitios web, literatura gris y estudios publicados con respecto al análisis de 16 indicadores en 4 categorías: comportamientos diarios, estado físico, entornos y fuentes influyentes, y estrategias e inversión. Los datos fueron cotejados con los puntos de referencia establecidos. A cada indicador se le asignó una calificación entre 1 y 10 (< 6 significa reprobado) o fue marcado como “incompleto” si los datos eran nulos o insuficientes. Resultados. Las calificaciones obtenidas para los comportamientos diarios fueron: actividad física en general: 4; participación en actividades deportivas organizadas: 5; juego activo: 3; modalidades de transporte activas: 5; sueño: 7; y sedentarismo: 3. El estado físico obtuvo un 7. Las calificaciones para los entornos y fuentes influyentes fueron: familiares y pares: “incompleto”; escuela: 3; comunidad y entorno: 4. Para las estrategias e inversión: estrategias gubernamentales: 6; entidades no gubernamentales: 2. Conclusiones. Las bajas calificaciones obtenidas en 11 de los 16 indicadores demuestran que las escuelas, las familias, las comunidades y el gobierno tienen que aunar esfuerzos para mejorar las oportunidades que tiene la población infantil y joven en México para desarrollar niveles de actividad física satisfactorios.

Objective. This paper describes the rationale, design, and methods of a two-year randomized controlled trial conducted to evaluate the effectiveness of an environmental intervention in 27 elementary schools in Mexico City. Materials and methods. There were two units of analysis, school level addressing changes in elementary public part-time schools, and individual-level addressing behavioral changes in students 9 to 11 years of age. Two intensities of an intervention program were implemented (basic and plus), each containing two intervention components: physical activity and nutrition, supported by a communication/education component. Evaluation of the intervention was carried out during the school cycles 2006-2007 and 2007-2008. Results. Primary outcomes were overweight and obesity prevalence and fitness; environmental and behavioural measures were also examined. Conclusions. This is the first institutional multilevel, multifactorial project, consistent with the best practices available in current literature, carried out in Mexico to prevent childhood obesity in schools.

Objetivo. El presente trabajo describe el protocolo, objetivo, el diseño y los métodos de un ensayo controlado aleatorio de dos años realizados para evaluar la efectividad de una intervención ambiental en 27 escuelas primarias de la Ciudad de México. Material y métodos. El protocolo consta de dos unidades de análisis: el nivel escolar donde se evaluaron los cambios en el entorno escolar de escuelas primarias publicas de medio tiempo y el nivel individual que evaluó los cambios de comportamiento en alumnos de 9 a 11 años de edad. Se implementaros dos tipos de intervenciones: nutrición y actividad física apoyadas de una estrategia de educación/comunicación. Las intervenciones tuvieron dos intensidades: básica y plus. La evaluación de la efectividad se llevó a cabo durante los ciclos escolares 2006-2007 y 2007-2008. Resultados. Los resultados iniciales reportan los métodos de evaluación de conducta individual así como la prevalencia de sobrepeso y obesidad. La evaluación ambiental reporta el protocolo de evaluación del entorno escolar. Conclusiones. Este es el primer proyecto de la de intervención escolar con un diseño multinivel, multifactorial, basado en literatura científica disponible y en investigación formativa para prevenir la obesidad infantil en las escuelas de la Ciudad de México.

Objective. This paper describes the rationale, design, and methods of a two-year randomized controlled trial conducted to evaluate the effectiveness of an environmental intervention in 27 elementary schools in Mexico City. Materials and methods. There were two units of analysis, school level addressing changes in elementary public part-time schools, and individual-level addressing behavioral changes in students 9 to 11 years of age. Two intensities of an intervention program were implemented (basic and plus), each containing two intervention components: physical activity and nutrition, supported by a communication/education component. Evaluation of the intervention was carried out during the school cycles 2006-2007 and 2007-2008. Results. Primary outcomes were overweight and obesity prevalence and fitness; environmental and behavioural measures were also examined. Conclusions. This is the first institutional multilevel, multifactorial project, consistent with the best practices available in current literature, carried out in Mexico to prevent childhood obesity in schools.

Objetivo. El presente trabajo describe el protocolo, objetivo, el diseño y los métodos de un ensayo controlado aleatorio de dos años realizados para evaluar la efectividad de una intervención ambiental en 27 escuelas primarias de la Ciudad de México. Material y métodos. El protocolo consta de dos unidades de análisis: el nivel escolar donde se evaluaron los cambios en el entorno escolar de escuelas primarias publicas de medio tiempo y el nivel individual que evaluó los cambios de comportamiento en alumnos de 9 a 11 años de edad. Se implementaros dos tipos de intervenciones: nutrición y actividad física apoyadas de una estrategia de educación/comunicación. Las intervenciones tuvieron dos intensidades: básica y plus. La evaluación de la efectividad se llevó a cabo durante los ciclos escolares 2006-2007 y 2007-2008. Resultados. Los resultados iniciales reportan los métodos de evaluación de conducta individual así como la prevalencia de sobrepeso y obesidad. La evaluación ambiental reporta el protocolo de evaluación del entorno escolar. Conclusiones. Este es el primer proyecto de la de intervención escolar con un diseño multinivel, multifactorial, basado en literatura científica disponible y en investigación formativa para prevenir la obesidad infantil en las escuelas de la Ciudad de México.

OBJECTIVE: To quantify the physical activity (PA) of students and describe the school environment surrounding PA. MATERIAL AND METHODS: Between November 2005 and March 2006, in Mexico City, we conducted quantitative and qualitative observations to describe the PA and the school context. RESULTS: Recess and physical education class (PE) were the only opportunities to participate in PA. PE occurred one time per week with a duration of 39.8±10.6 minutes which is less than national and international recommendations. Students participated in moderate-to-vigorous PA 29.2±17.8% of PE. The dynamics of PE did not promote the inclusion of all students or PA. During recess there was overcrowding of the school patio and no equipment for PA or organization of PA. DISCUSSION: The PA of students in public schools in Mexico City can be improved by increasing the quantity and quality of PE and increasing opportunities for activity during recess.

OBJETIVO: Cuantificar la actividad física (AF) en niños escolares y describir el entorno escolar relacionado con la AF. MATERIAL Y MÉTODOS: Entre noviembre de 2005 y marzo de 2006 en la Ciudad de México, se realizó observación directa cuantitativa y cualitativa para describir el nivel de AF y el contexto escolar durante recreo y clases de educación física (CEF). RESULTADOS: El recreo y las CEF fueron los únicos espacios en los que se realizó AF. Las CEF se impartieron una vez a la semana y duraron 39.8±10.6 minutos, lo que está por debajo de las recomendaciones internacionales. Se participó en actividades moderadas-vigorosas 29.2±17.8% de las CEF. La dinámica de las CEF no favoreció la AF. Durante el recreo se observó saturación del patio y no se realizaron actividades organizadas ni se utilizaron materiales para promover la AF. DISCUSIÓN: Se recomienda incrementar la calidad y la cantidad de las CEF y el tiempo dedicado a jugar durante el recreo.

OBJECTIVE: To quantify the physical activity (PA) of students and describe the school environment surrounding PA. MATERIAL AND METHODS: Between November 2005 and March 2006, in Mexico City, we conducted quantitative and qualitative observations to describe the PA and the school context. RESULTS: Recess and physical education class (PE) were the only opportunities to participate in PA. PE occurred one time per week with a duration of 39.8±10.6 minutes which is less than national and international recommendations. Students participated in moderate-to-vigorous PA 29.2±17.8% of PE. The dynamics of PE did not promote the inclusion of all students or PA. During recess there was overcrowding of the school patio and no equipment for PA or organization of PA. DISCUSSION: The PA of students in public schools in Mexico City can be improved by increasing the quantity and quality of PE and increasing opportunities for activity during recess.

OBJETIVO: Cuantificar la actividad física (AF) en niños escolares y describir el entorno escolar relacionado con la AF. MATERIAL Y MÉTODOS: Entre noviembre de 2005 y marzo de 2006 en la Ciudad de México, se realizó observación directa cuantitativa y cualitativa para describir el nivel de AF y el contexto escolar durante recreo y clases de educación física (CEF). RESULTADOS: El recreo y las CEF fueron los únicos espacios en los que se realizó AF. Las CEF se impartieron una vez a la semana y duraron 39.8±10.6 minutos, lo que está por debajo de las recomendaciones internacionales. Se participó en actividades moderadas-vigorosas 29.2±17.8% de las CEF. La dinámica de las CEF no favoreció la AF. Durante el recreo se observó saturación del patio y no se realizaron actividades organizadas ni se utilizaron materiales para promover la AF. DISCUSIÓN: Se recomienda incrementar la calidad y la cantidad de las CEF y el tiempo dedicado a jugar durante el recreo.