Short sleep duration is associated with increased obesity markers in European adolescents: effect of physical activity and dietary habits. The HELENA study.

BACKGROUND: Adequate sleep is a critical factor for adolescent's health and health-related behaviors. OBJECTIVE: (a) to describe sleep duration in European adolescents from nine countries, (b) to assess the association of short sleep duration with excess adiposity and (c) to elucidate if physical activity (PA), sedentary behaviors and/or inadequate food habits underlie this association. DESIGN: A sample of 3311 adolescents (1748 girls) aged 12.5-17.49 years from 10 European cities in Austria, Belgium, France, Germany, Greece, Hungary, Italy, Spain and Sweden was assessed in the Healthy Lifestyle in Europe by Nutrition in Adolescence Study between 2006 and 2008. We measured anthropometric data, sleep duration, PA (accelerometers and questionnaire), television watching and food habits (Food Frequency Questionnaire). RESULTS: Average duration of daily sleep was 8 h. Shorter sleepers showed higher values of BMI, body fat, waist and hip circumferences and fat mass index (P<0.05), particularly in females. Adolescents who slept <8 h per day were more sedentary, as assessed by accelerometry, and spent more time watching TV (P<0.05). The proportion of adolescents who eat adequate amounts of fruits, vegetables and fish was lower in shorter sleepers than in adolescents who slept ≥8 h per day, and so was the probability of having adequate food habits (P<0.05). Correlation analysis indicated that short sleep is associated with higher obesity parameters. CONCLUSIONS: In European adolescents, short sleep duration is associated with higher adiposity markers, particularly in female adolescents. This association seems to be related to both sides of the energy balance equation due to a combination of increased food intake and more sedentary habits.

Sampling and processing of fresh blood samples within a European multicenter nutritional study: evaluation of biomarker stability during transport and storage.

INTRODUCTION: Analysis of several biological markers improves the quality and physiologic comprehension of data obtained in epidemiological nutritional studies. AIM: To develop a methodology that guarantees the centralized analysis and quality assurance of the most relevant blood parameters from fresh blood samples in adolescents in a European multicenter study. MATERIALS AND METHODS: Stability of selected nutrients and biomarkers (vitamins, fatty acids, iron metabolism and immunological parameters) chosen with respect to time and temperature of sample transport and storage was evaluated as part of the pilot study of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) project. RESULTS: Routine biochemistry and iron status parameters included in the HELENA Cross-Sectional Study (CSS) protocol could be analyzed within 24 h from fresh blood samples without any stability problems (coefficient of variation (CV)<5%, P<0.05). However, stability tests for lymphocyte subpopulations, vitamin C and fatty acids showed that they are very unstable at room temperature without any treatment. Therefore, a special handling for these samples was developed. Vitamin C was stabilized with metaphosphoric acid and transported under cooled conditions (CV 4.4%, recovery rate >93%, P>0.05). According to the results, a specific methodology and transport system were developed to collect blood samples at schools in 10 European cities and to send them to the centralized laboratory (IEL, Bonn, Germany). To guarantee good clinical practice, the field workers were instructed in a training workshop and a manual of operation was developed. CONCLUSION: The handling and transport system for fresh blood samples developed for the European multicenter study HELENA is adequate for the final part of the HELENA-CSS and will provide, for the first time, reference values for several biological markers in European adolescents.

B-vitamin status and intake in European adolescents. A review of the literature.

BACKGROUND: National and international recommendations for the intake of B vitamins in adolescents consist of estimates and extrapolations from adult values. Due to increasing growth and therefore relatively high energy and nutrient requirements adolescents are a vulnerable group from the nutritional point of view. In addition, a deficient intake of several B vitamins is strongly connected with the development of cancer, neural tube defects and cardiovascular diseases. OBJECTIVE: The aim of this work is to assess dietary intake and status of B vitamins and homocysteine of European adolescents on the basis of published data. METHODS: The database Medline (www.ncvi.nlm.nih.gov) was searched for terms like "Vitamin B", "homocysteine", "Europe", etc. Studies published between June 1980 and December 2004 were analysed for this review. Results of the intake of B vitamins were compared with the EAR or AI, respectively, as recommended by the U.S. Institute of Medicine. Due to lacking reference values for adolescents results of blood status as well as homocysteine were compared to different thresholds for adults. RESULTS: Considering the limitations of the comparability between the reviewed studies e.g. by different methodologies, sample size, age groups, the average intake of B vitamins surpassed the EAR and AI. Boys were better supplied with B vitamins than girls. The intake decreased with increasing age in both genders. A possible deficiency of folate was noticed and girls in particular seemed to be more at risk. Clear regional tendencies for the vitamin intake could not be observed. Results of vitamin B6, B12, folate in blood, and homocysteine were levelled in-between the thresholds. Though the great standard deviation of folate increased the probability of a deficient supply in parts of the population. CONCLUSIONS: European girls seem to be at risk of folate deficiency. Supplements and fortified food were not taken into consideration by most of the published studies which additionally distorts the real intake. Standardized methods of dietary surveys and reference values for B vitamins as well as homocysteine still must be established. Hence, further investigations are of great relevance. folate increased the probability of a deficient supply in parts of the population. CONCLUSIONS: European girls seem to be at risk of folate deficiency. Supplements and fortified food were not taken into consideration by most of the published studies which additionally distorts the real intake. Standardized methods of dietary surveys and reference values for B vitamins as well as homocysteine still must be established. Hence, further investigations are of great relevance.

B-Vitamin status and intake in European adolescents. A review of the literature / Estado vitamínico e ingesta de vitaminas en adolescentes europeos. Revisión bibliográfica

Background: National and international recommendations for the intake of B vitamins in adolescents consist of estimates and extrapolations from adult values. Due to increasing growth and therefore relatively high energy and nutrient requirements adolescents are a vulnerable group from the nutritional point of view. In addition, a deficient intake of several B vitamins is strongly connected with the development of cancer, neural tube defects and cardiovascular diseases. Objective: The aim of this work is to assess dietary intake and status of B vitamins and homocysteine of European adolescents on the basis of published data. Methods: The database Medline (www.ncvi.nlm.nih. gov) was searched for terms like “vitamin B”, “homocysteine”, “Europe”, etc. Studies published between June 1980 and December 2004 were analysed for this review. Results of the intake of B vitamins were compared with the EAR or AI, respectively, as recommended by the U.S. Institute of Medicine. Due to lacking reference values for adolescents results of blood status as well as homocysteine were compared to different thresholds for adults. Results: Considering the limitations of the comparability between the reviewed studies e.g. by different methodologies, sample size, age groups, the average intake of B vitamins surpassed the EAR and AI. Boys were better supplied with B vitamins than girls. The intake decreased with increasing age in both genders. A possible deficiency of folate was noticed and girls in particular seemed to be more at risk. Clear regional tendencies for the vitamin intake could not be observed. Results of vitamin B6, B12, folate in blood, and homocysteine were levelled in-between the thresholds. Though the great standard deviation of folate increased the probability of a deficient supply in parts of the population. Conclusions: European girls seem to be at risk of folate deficiency. Supplements and fortified food were not taken into consideration by most of the published studies which additionally distorts the real intake. Standardized methods of dietary surveys and reference values for B vitamins as well as homocysteine still must be established. Hence, further investigations are of great relevance

Antecedentes: Las recomendaciones, tanto nacionales como internacionales, sobre el consumo de vitamina B por adolescentes, se basan en valoraciones y extrapolaciones de datos de adultos. Los adolescentes debido a su crecimiento y desarrollo, y, por ello, a la necesidad relativamente alta de energía y nutrientes, son desde el punto de vista de la nutrición un grupo vulnerable. Además, una insuficiente ingesta de varias vitaminas B se relaciona con el desarrollo de cáncer, defectos del tubo neural y enfermedades cardiovasculares Objetivo: El objetivo de este trabajo es valorar el estado vitamínico y de homocisteina y la ingesta de vitaminas B en adolescentes europeos, basándose en datos publicados Método: La base de datos Medline (www.ncvi.nlm.nih. gov), se analizó en función de términos tales como “Vitamina B” “Homocisteina”, “Europa”…, etc. Para esta revisión se analizaron estudios publicados entre junio de 1980 y diciembre de 2004. Los resultados de ingesta de vitamina B se compararon, respectivamente, con los de EAR y AI, según recomendación del Instituto de Medicina de EEUU. Debido a las lagunas de valores de referencia para adolescentes, los resultados se compararon con los diferentes umbrales para adultos. Resultados: Considerando las limitaciones de la comparación en la revisión de estudios, por ejemplo: diferentes metodologías, tamaño de muestras, grupos de edad, etc., la media de ingesta de vitamina B sobrepasa a la de EAR y AI. Los chicos están mejor proveídos de vitamina B que las chicas. La ingesta decrecía con la edad en ambos géneros. Se apreciaba una posible deficiencia de fólico y las chicas, en particular, parecían padecer más riesgos. No se observaron claras tendencias regionales en la ingesta de vitaminas. Los niveles de vitaminas B6 y B12, fólico y homocisteina en sangre se encontraron dentro de los valores de referencia. No obstante, la enorme desviación estándar de fólico incrementaba la posibilidad de un deficiente consumo en parte de la población Conclusión: Las chicas europeas parecen estar a riesgo de deficiencia de fólico. Los suplementos y alimentos enriquecidos no fueron considerados en la mayoría de los estudios publicados, lo cual desvirtuaba la ingesta real. Todavía se deben establecer métodos estandarizados de registro dietético y valores de referencia, tanto para vitaminas del grupo B como para homocisteina. Por lo tanto, son necesarias investigaciones futuras