Overweight-obesity increased in girls and females, mainly from rural areas. Strategies focued in containing this phenomenon are encouraged to implement in this context.

Objetivo. Describir el diseño metodológico de la Encuesta Nacional de Salud y Nutrición de Medio Camino (Ensanut- MC) 2016. Material y métodos. La Ensanut-MC es una encuesta probabilística nacional cuya población objetivo son los habitantes de viviendas particulares en México. El tamaño de muestra se determinó para poder hacer inferencias sobre las localidades urbanas y rurales de cuatro regiones. Se descri­ben los elementos principales del diseño: población objetivo, temas de estudio, procedimiento de muestreo, procedimien­to de medición y organización logística. Resultados. Se obtuvieron 9 479 entrevistas de hogar completas y 16 591 entrevistas de individuos completos. La tasa de respuesta de hogar fue 77.9%. La tasa de respuesta de individuo fue 91.9%. Conclusiones. El diseño probabilístico de la Ensanut-MC permite hacer inferencias estadísticas válidas sobre paráme­tros de interés para la salud y nutrición pública de México, específicamente en variables de sobrepeso, obesidad y diabetes mellitus. Asimismo, la información actualizada sustentará el monitoreo, la actualización y formulación de nuevas políticas y programas prioritarios.

Objective. To describe the methodology used to clean up and estimate dietary intake (DI) data from the SemiQuantitative Food Frequency Questionnaire (SFFQ) of the Mexican National Health and Nutrition Survey 2012. Materials and methods. DI was collected through a shortterm SFFQ regarding 140 foods (from October 2011 to May 2012). Energy and nutrient intake was calculated according to a nutrient database constructed specifically for the SFFQ. Results. A total of 133 nutrients including energy and fiber were generated from SFFQ data. Between 4.8 and 9.6% of the survey sample was excluded as a result of the cleaning process. Valid DI data were obtained regarding energy and nutrients consumed by 1 212 pre-school children, 1 323 school children, 1 961 adolescents, 2 027 adults and 526 older adults. Conclusions. We documented the methodology used to clean up and estimate DI from the SFFQ used in national dietary assessments in Mexico.

A high percentage of the population do not consume fruits, vegetables and plain water daily.

Seroprevalence surveys provide estimates of the extent of SARS-CoV-2 infections in the population, regardless of disease severity and test availability. In Mexico in 2020, COVID-19 cases reached a maximum in July and December. We aimed to estimate the national and regional seroprevalence of SARS-CoV-2 antibodies across demographic and socioeconomic groups in Mexico after the first wave, from August to November 2020. We used nationally representative survey data including 9,640 blood samples. Seroprevalence was estimated by socioeconomic and demographic characteristics, adjusting by the sensitivity and specificity of the immunoassay test. The national seroprevalence of SARS-CoV-2 antibodies was 24.9% (95%CI 22.2, 26.7), being lower for adults 60 years and older. We found higher seroprevalence among urban and metropolitan areas, low socioeconomic status, low education and workers. Among seropositive people, 67.3% were asymptomatic. Social distancing, lockdown measures and vaccination programs need to consider that vulnerable groups are more exposed to the virus and unable to comply with lockdown measures.

Objetivo. Describir el diseño metodológico de la Encuesta Nacional de Salud y Nutrición en localidades con menos de 100 000 habitantes (Ensanut 100k). Material y métodos. La Ensanut 100k es una encuesta probabilística que sobrerre­presenta a los hogares con menos capacidades económicas. Se describe el alcance de la encuesta, los procedimientos de muestreo, medición e inferencia y la organización logística. Resultados. Se obtuvieron 10 461 entrevistas de hogar y 26 161 de individuos. La tasa de respuesta de hogar fue 89% y de individuos 92%. Conclusiones. El diseño probabilístico de la Ensanut 100k permite hacer inferencias estadísticas válidas sobre parámetros de interés para la salud pública en localidades con menos de 100 000 habitantes, localidades donde vive 52% de la población según el censo de 2010. La comparabilidad de los resultados con la Ensanut 2012 facilita evaluar las acciones de apoyo que otorga el gobierno a poblaciones con menores capacidades económicas en el periodo 2012-2018.

Objective. To describe the prevalence of iron, folate, and B12 deficiencies in Mexican women of reproductive age from the National Health and Nutrition Survey (Ensanut) 2012.Materials and methods. Data came from a  ationalprobabilistic survey, representative from rural and urban areas,and different age groups. Blood samples were obtained from 4 263, 20 to 49 years old women for serum ferritin, vitamin B12 and serum folate oncentrations. The prevalence of deficiencies, was assessed using adjusted logistic regression models. Results. The deficiency of folate was 1.9% (95%CI1.3-2.8), B12 deficiency was 8.5% (95%CI 6.7-10.1) and iron deficiency was 29.4% (95%CI 26.5-32.2). No differences were found when compared with 2006, 24.8% (95%CI 22.3-27.2).Conclusions. The vitamin B12 deficiency is still a problem for women of reproductive age and their offspring in Mexico,while folate deficiency disappeared as a problem. Iron deficiency needs prevention and fortification strategies.

We conclude that the adjusting-by-variance method using 3 d of 24HR allows for a more accurate estimation of usual intake, dietary adequacy, and prevalence of inadequacy, thereby reducing the measurement error that could compromise the results and conclusions of surveys.