Healthy Lifestyle In Europe By Nutrition In Adolescence Cross-Sectional Study Research Articles

New indices in predicting cardiometabolic risk and its relation to endothelial dysfunction in adolescents: The HELENA study

Background and aimsBlood pressure (BP) changes and insulin resistance (IR) are important cardiometabolic risk (CMR) factors; their early identification can contribute to the reduction of cardiovascular events in adulthood. This necessitates the search for more accessible and easily applied indicators for their prediction. Therefore, this study aimed to evaluate the predictive power of the indices, TyG, TG/HDL-c, height-corrected lipid accumulation product (HLAP), and visceral adiposity index (VAI), in identifying the CMR obtained by high BP and IR and to verify their relationship with biomarkers of endothelial dysfunction (ED) in European adolescents. Methods and resultsThe anthropometric data and blood biomarkers of 744 adolescents (343 boys and 401 girls) from the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS), with a mean age of 14.67 (SD 1.15) years, were assessed. The adolescents were then classified according to the presence or absence of high BP and IR. The cut-off points of the indices evaluated for the identification of CMR were determined. The relationship between CMR diagnosed using these indices and ED biomarkers was tested. The HLAP and TG/HDL-c were fair predictors of CMR obtained by IR in male adolescents. These indices showed association with hsCRP in sVCAM-1 in boys, but it lost significance after adjusting for age and body mass index. ConclusionTG/HDL-c and HLAP indices showed a fair performance in predicting CMR, obtained by IR, in male adolescents. ED showed no association with the CMR identified by the indices.

Food portion sizes and their relationship with energy, and nutrient intakes in adolescents: The HELENA study

ObjectivesThis study aimed to investigate the associations between portion sizes (PSs) from different food groups and energy, as well as nutrient intakes in European adolescents. MethodsA sample of 1631 adolescents (54.2 % girls) were included from the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional (HELENA) study. Mean food PS was calculated by dividing the total intake of the items by the number of eating occasions of these consumed items. To determine the key items for analysis, foods were ranked by frequency of consumption. A one-way between-groups analysis of covariance was used to test for significant differences in means across tertiles. A multivariable linear regression analysis was carried out, adjusting for age, sex, maternal education, body mass index, and using country as a level. ResultsEnergy intake increased with elevated intakes of energy-dense foods. Large portions of rice and other grains, starch roots and potatoes, and meat substitutes, nuts, and pulses were associated with increased carbohydrate and fiber intake. Larger portions of cheese and butter and animal fat were significantly associated with a higher fat intake. Lower intakes of some vitamins and micronutrients were noticed with consumption of larger portions of high energy-dense foods, such as desserts and pudding, margarine and vegetable oil, and butter and animal fat. ConclusionsLarge food PSs may be associated with positive energy, as well as macro- and micronutrient intake. Moreover, the findings from this study may help the future development of dietary guidance in general and specific to PSs, and support targeted strategies to address intakes of certain nutrients in European adolescents.

Abdominal obesity and its association with socioeconomic factors among adolescents from different living environments.

Socioeconomic status has been associated with obesity in children and adolescents. This association may be dependent according with where adolescents lives. The aim of this study was to evaluate the association between different socioeconomic indicators such as parental education and occupation and socioeconomic status with abdominal obesity in adolescents from two observational studies: the Healthy Lifestyle in Europe by Nutrition in Adolescence cross-sectional study (HELENA-CSS) and the Brazilian Cardiovascular Adolescent Health (BRACAH) study. European (n = 3192, aged 12.5-17.5 years, with 53.1% girls from HELENA-CSS) and Brazilian (n = 991, aged 14-18 years, with 54.5% girls from BRACAH study) adolescents from two cross-sectional studies were included in this analysis. Complete data on waist circumference (WC), height, socioeconomic status indicators and several confounders were collected. Socioeconomic indicators were measured using a self-reported questionnaire in order to assess the family social status of the adolescents. Multilevel linear regression models were used to examine associations, and results were adjusted for potential confounders. Adjusted results showed inverse associations between mother's and father's education levels (p < 0.001) and father's occupation level (p < 0.001) with waist-to-height ratio (WHtR) and WC in HELENA-CSS girls. Similarly in European girls, socioeconomic indicators by socioeconomic status and maternal occupation level were associated with WHtR. In HELENA-CSS boys, the same significant association was found between WHtR and WC with maternal occupation level. Moreover, in European boys WHtR was also associated with parental education. In Brazilian adolescents, both indicators of abdominal obesity did not remain associated with the independents variables, after adjustment for potential confounders. Abdominal obesity was associated with socioeconomic indicators in higher-income countries, but this association was not observed in a lower-middle-income country.

Association between chocolate consumption and fatness in European adolescents

ObjectiveThere is a substantial interest in the potential role of chocolate in the prevention of cardiovascular diseases. It has been recently reported that a higher frequency of chocolate intake is linked to lower body mass index (BMI) in adults. The aim of the present study was to determine if higher chocolate consumption also is associated with lower BMI, as well as other markers of total and central body fat, in adolescents. MethodsThis study comprised 1458 adolescents (ages 12.5–17.5 y) participating in HELENA-CSS (Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study). Dietary intake was self-registered using a computer-based tool for 24-h dietary recall on 2 non-consecutive days. Weight and height were measured, and BMI was calculated. Adiposity was estimated using skinfolds (Slaughter’s equation) and bioelectrical impedance analysis (BIA). Waist circumference was measured. Sexual maturation also was recorded. Physical activity was measured by accelerometry. ResultsHigher chocolate consumption was associated with lower levels of total and central fatness, as estimated by BMI, body fat estimated from skinfolds and BIA, and waist circumference, regardless of potential confounders (P ≤ 0.01). ConclusionOur results demonstrate that a higher chocolate consumption was associated with lower total and central fatness in European adolescents.

Lunch at school, at home or elsewhere. Where do adolescents usually get it and what do they eat? Results of the HELENA Study

Considering the lack of uniformity regarding school meals in Europe, information on adolescents’ school lunch patterns is of public health importance. Thus, the aim of this analysis was to describe and evaluate lunchtime energy and food intake of European adolescents at different lunch locations. Data on nutritional and health-related parameters were derived from the HEalthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS). A sub-sample of 891 adolescents (47% male) with plausible data on total and lunchtime energy intake (2×24h recall) as well as usual lunch location was considered. Food intake was compared to lunch of the Optimized Mixed Diet (OMD) for children and adolescents. Although energy intake was nearly in line with the recommendations, food intake was suboptimal compared to the OMD regardless of usual lunch location. Adolescents had more potatoes and less sweets at school, and more drinks (water, coffee and tea) and vegetables at home when each compared with the other locations. Food intake of adolescents getting their lunch elsewhere was characterized by the smallest amounts of potatoes and the highest amounts of sweets. Although lunch patterns may differ among countries, schools in Europe do not seem to reveal all their potential to offer access to a healthy lunch for adolescents yet.

Dietary and lifestyle quality indices with/without physical activity and markers of insulin resistance in European adolescents: the HELENA study

Emerging data indicate that higher levels of insulin resistance (IR) are common among children and adolescents and are related to cardiometabolic risk; therefore, IR requires consideration early in life. In addition, there is a lack of conclusive evidence regarding the role of dietary nutrients on IR. The Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS) was conducted in European adolescents aged 12·5–17·5 years. A total of 637 participants with valid homeostasis model assessment (HOMA) index data and who completed at least a 2 d 24 h dietary recall were included in the study (60% of the total HELENA-CSS sample). There were two dietary indices calculated, with the only difference between them being the inclusion or not of physical activity (PA). Markers of IR such as HOMA and the quantitative insulin sensitivity check index (QUICKI) were calculated. Pubertal status, BMI and cardiorespiratory fitness (CRF) were measured as potential confounders. The dietary index including PA was inversely associated with HOMA and directly with the QUICKI in females, but not in males, after adjusting for pubertal status, centre, BMI and CRF. In conclusion, the present study indicates that considering PA as part of the dietary index is of relevance as the resulted index is inversely related to IR independently of potential confounders including CRF. Overall, these findings suggest that intervention studies aimed at preventing IR in young people should focus on increasing the quality of the diet and also on including an optimal PA level in healthy adolescents.

Sleep duration and lymphocyte subsets profile in European adolescents. The HELENA Study

Insufficient sleep is associated with higher incidence of infections and worse recovery, and more recently with increased risk for noninfectious diseases and low-grade inflammation (1) . The immune system seems to be strongly influenced by the sleep/wake cycle and has its own circadian rhythm, in both its functions and circulating cell numbers (2) . During adolescence sleep patterns experience significant changes, such as delay of sleep initiation and/or reduction of the sleep duration; therefore, sleeping habits at this period may have an impact on the immune system. In the present work, absolute and relative counts of leukocyte types and lymphocyte subsets were compared between adolescents reporting to sleep less than 8 hours per night (short-sleep group) and those reporting 8 hours or more (sufficient sleep). Blood samples were collected after an overnight fast from 1,089 boys and girls (12.5‐17.5 years old; 53.3% females) participating in the HELENA-CSS (Healthy Lifestyle in Europe by Nutrition in Adolescence-Cross-Sectional Study). Leukocyte and lymphocyte subset counts were compared by means of analysis of covariance (ANCOVA), adjusting for country, gender, Tanner stage and body mass index (BMI). Non-normally distributed variables were previously log-transformed. Adolescents in the short-sleep group ( < 8h/night) presented higher counts and percentages of total T (CD3 + ; P < 0.05) and helper T (CD4 + ; P < 0.01) lymphocytes, higher counts of total memory T cells (CD3 + RO + ; P < 0.05) and memory helper T cells (CD4 + RO + ; P < 0.001), and lower percentages of natural killer cells (CD3 - CD16 + 56 + ; P < 0.05), independently of gender and BMI. Our results show a significant relationship between sleep duration and immune parameters in European adolescents, suggesting that sleep-related immune alterations can start at early life stages.

Lymphocyte subsets, anthropometric measurements and body composition in European adolescents. The HELENA Study

There is a close relationship between obesity and the immune system. Obese individuals have been shown to present higher immune cell counts, mainly of total leukocytes, but also of neutrophils, lymphocytes and monocytes (1) . The association between leukocyte count and obesity has been observed in children and adolescents as well (2,3) , and it could also occur with other cell types, e.g., T lymphocytes (4) . We have recently found a significant relation between total leukocytes and body mass index (BMI) in a cohort of European adolescents participating in the HELENA-CSS (Healthy Lifestyle in Europe by Nutrition in Adolescence-Cross-Sectional Study) (unpublished data). For the present work we studied further the relationships between lymphocyte subset counts and body composition and anthropometric measurements in this adolescent cohort. Blood samples were collected after an overnight fast from 1,089 boys and girls (12.5‐17.5 years). After applying exclusion criteria to rule out possible infections, data were analysed from 751 adolescents (47.5% males). The sample was divided into three categories according to tertiles of standardized BMI values. Absolute and relative numbers of total T lymphocytes

White blood cell count is associated with features of the metabolic syndrome in European adolescents. The HELENA Study

The aim of the present work was to analyse the relationships between WBCC and obesity and features of the metabolic syndrome in a cohort of European adolescents participating in the HELENA-CSS (Healthy Lifestyle in Europe by Nutrition in Adolescence-CrossSectional Study). Blood samples were collected after an overnight fast from 1,089 participants aged 12.5‐17.5 years. After applying exclusion criteria (having fever and/or having received any medical treatment 24 hours prior to extraction), data were analysed from 952 adolescents (47.3% males). The sample was divided into four categories according to WBCC quartiles. Height, weight, body mass index (BMI), body fat mass and percentage, waist circumference, blood pressure (SBP and DBP), serum glucose, lipids, insulin, and indices of insulin resistance (HOMA-IR) and sensitivity (QUICKY-IS) were compared between groups by analysis of covariance (ANCOVA), adjusting for country, gender and age. Non-normally distributed variables were previously log-transformed. According to our data, adolescents with higher WBCC presented significantly higher weight (P < 0.01), BMI, body fat, waist circumference (all P < 0.001), DBP (P < 0.01), serum triglycerides (P < 0.001), total cholesterol/HDL-cholesterol and LDL/HDL-cholesterol ratios (P < 0.01), serum insulin and HOMA-IR index (both P < 0.001), and significantly lower values of serum HDL-cholesterol and QUICKY-IS index (both P < 0.001). These results support a significant positive association between WBCC and obesity and metabolic syndrome, and suggest that WBCC can be a useful marker to assess cardio-metabolic risk in European adolescents.

Daily sugar-sweetened beverage consumption and insulin resistance in European adolescents: the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study.

The present study aimed to evaluate the relationship between the consumption of selected food groups and insulin resistance, with an emphasis on sugar-sweetened beverages (SSB). The present research is a large multicentre European study in adolescents, the HELENA-CSS (Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study). Homeostasis model assessment-insulin resistance index (HOMA-IR) was calculated. Several anthropometric and lifestyle characteristics were recorded. Dietary assessment was conducted by using a short FFQ. The participants were a subset of the original sample (n 546) with complete data on glucose, insulin and FFQ. All participants were recruited at schools. Median (25th, 75th percentile) HOMA-IR was 0.62 (0.44, 0.87). Mean HOMA-IR was significantly higher among adolescents consuming brown bread ≤1 time/week than among those consuming 2-6 times/week (P = 0·011). Mean values of HOMA-IR were also higher in adolescents consuming SSB >5 times/week compared with those consuming less frequently, although a statistically significant difference was detected between those consuming SSB 5-6 times/week and 2-4 times/week (P = 0.049). Multiple linear regression analysis showed that only the frequency of SSB consumption was significantly associated with HOMA-IR after controlling for potential confounders. In particular, it was found that HOMA-IR levels were higher among adolescents consuming SSB 5-6 times/week and ≥1 time/d compared with those consuming ≤1 time/week by 0.281 and 0.191 units, respectively (P = 0.009 and 0.046, respectively). The present study revealed that daily consumption of SSB was related with increased HOMA-IR in adolescents.

Associations of Dietary Calcium, Vitamin D, Milk Intakes, and 25-Hydroxyvitamin D With Bone Mass in Spanish Adolescents: The HELENA Study

Adequate nutrition is needed for the accrual of bone mass during the pre- and postpubertal growth periods. This study aimed to examine the associations between dietary calcium, vitamin D (calciferol), and milk intakes and 25-hydroxyvitamin D [25(OH)D] status and bone mineral content (BMC) and bone mineral density (BMD) in Spanish adolescents, aged 12.5–17.5yr, participating in the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS). Bone mass was measured with dual-energy X-ray absorptiometry and diet via 2 nonconsecutive 24-h dietary recalls (n=227; 48% males). A random subsample of 101 adolescents (46% males) had available measures of 25(OH)D. Multiple linear regression was applied. Significant adjusted associations were observed in males, among milk intakes and BMC and BMD. Also in males, whole-body, head, and right arm BMD were positively related to calcium intakes. In females, 25(OH)D was positively related among others to whole-body, subtotal, and left and right arm BMC and BMD. It could be speculated that diet is not a limiting factor of bone mass development in this group of healthy adolescents, and further research on the effect of other factors in addition to diet in a larger sample should be undertaken.

Beverage consumption among European adolescents in the HELENA study

Our objective was to describe the fluid and energy consumption of beverages in a large sample of European adolescents. We used data from 2741 European adolescents residing in 8 countries participating in the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS). We averaged two 24-h recalls, collected using the HELENA-dietary assessment tool. By gender and age subgroup (12.5-14.9 years and 15-17.5 years), we examined per capita and per consumer fluid (milliliters (ml)) and energy (kilojoules (kJ)) intake from beverages and percentage consuming 10 different beverage groups. Mean beverage consumption was 1611 ml/day in boys and 1316 ml/day in girls. Energy intake from beverages was about 1966 kJ/day and 1289 kJ/day in European boys and girls, respectively, with sugar-sweetened beverages (SSBs) (carbonated and non-carbonated beverages, including soft drinks, fruit drinks and powders/concentrates) contributing to daily energy intake more than other groups of beverages. Boys and older adolescents consumed the most amount of per capita total energy from beverages. Among all age and gender subgroups, SSBs, sweetened milk (including chocolate milk and flavored yogurt drinks all with added sugar), low-fat milk and fruit juice provided the highest amount of per capita energy. Water was consumed by the largest percentage of adolescents followed by SSBs, fruit juice and sweetened milk. Among consumers, water provided the greatest fluid intake and sweetened milk accounted for the largest amount of energy intake followed by SSBs. Patterns of energy intake from each beverage varied between countries. European adolescents consume an average of 1455 ml/day of beverages, with the largest proportion of consumers and the largest fluid amount coming from water. Beverages provide 1609 kJ/day, of which 30.4%, 20.7% and 18.1% comes from SSBs, sweetened milk and fruit juice, respectively.

Reliability and validity of a screen time-based sedentary behaviour questionnaire for adolescents: The HELENA study

Although there is a growing interest in the epidemiology of sedentary behaviours, it is unknown whether sedentary behaviour questionnaires are broad markers of sedentary time. The aims of this study were to determine the: (i) reliability of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) screen time-based sedentary behaviour questionnaire; and (ii) its validity, i.e. the ability of the questionnaire to correctly rank adolescents according to the objectively measured sedentary time. A total of 183 adolescents (104 females aged 12.5-17.5 years) were involved in the reliability study. Participants completed the HELENA sedentary questionnaire twice (1 week apart). The validity study comprised 2048 (1212 females) adolescents (12.5-17.5 years of age) included in the HELENA cross-sectional study. Questions included television viewing, computer games, console games, Internet for study and non-study reasons and study during week and weekend days. We compared median values of sedentary time, using accelerometers, by tertiles of self-reported sedentary behaviours and their sum (composite sedentary score). Reliability study: κ-values showed a good agreement (>0.7), except for Internet for study reasons (0.46 weekdays, 0.33 weekend). The questionnaire correctly classified boys' sedentary time when analysed by specific behaviours and by a composite sedentary score. In girls, median values of objectively measured sedentary time were not different across tertiles of self-reported sedentary behaviours or the composite sedentary score. The HELENA sedentary questionnaire is reliable, yet only correctly classifies objectively measured sedentary time in boys.

Socioeconomic status influences physical fitness in European adolescents independently of body fat and physical activity: the HELENA study.

The influence of socioeconomic status on health-related fitness is not clear. To examine the influence of socioeconomic status on health-related fitness in adolescents. A total of 3,259 adolescents (15.0 +/- 1.3 y) from the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS) participated in the study. Socioeconomic status was assessed by the family affluence scale (FAS). Speed-agility, muscular strength and cardiorespiratory fitness were assessed. Covariates included total body fat, physical activity and pubertal status. Adolescents with high FAS had significantly higher fitness levels than their peers of lower FAS categories except for speed-agility and handgrip in boys. Overall, the associations observed presented a medium to large effect size. These results suggest that socioeconomic status is positively associated with physical fitness in European adolescents independently of total body fat and habitual physical activity.

Quality assurance of ethical issues and regulatory aspects relating to good clinical practices in the HELENA Cross-Sectional Study

Research involving humans is regulated by regulatory authorities through their specific requirements and controls. The Healthy Life Style in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS) is a multicenter biomedical research study of adolescents in several representative European cities, which requires satisfying medico-regulatory requirements including Independent Ethics Committee (IEC) approval and agreement by the national or local regulatory authorities. To achieve a high level of quality assurance relating to ethical issues, we followed the good clinical practices (GCP) described at the International Conference on Harmonisation (ICH), which we adapted to the national and local situations of each of the 11 participating cities in 10 European countries. The main objective of the HELENA-CSS is to evaluate reliable and comparable data of nutritional habits and lifestyle in a representative sample of European adolescents. The aim of this paper is to present the methods relating to the ethical and regulatory issues of this study and to describe the current state of the medico-regulatory requirements involved in conducting this kind of study in each country. Following the GCP-ICH guidelines, a protocol describing the HELENA-CSS was written and approved by all partners. In the pilot study, a case report form adapted to the study objectives and its manual of operation was constructed and used by all partners. All information letters to adolescents and their parents and consent forms were first written in English, then translated into the local language, and adapted to each local situation. All documents were then checked centrally for any deviation and corrected if required. An operation manual relating to ethical issues and other medico-regulatory requirements was also developed. This paper presents the current status of the medico-regulatory requirements from each HELENA-CSS participant country. Before the beginning of the study, most centers had satisfied the medico-regulatory requirements of IEC approval and agreement with other national or local regulatory authorities/organizations. For a few centers, some problems were detected and corrective actions were taken to improve missing information to reach a high level of quality assurance of ethical issues. The GCP-ICH guidelines about nontherapeutic biomedical research are interpreted and applied differently across Europe. This study shows that high-quality nontherapeutic biomedical research can address the ethical issues included in the GCP-ICH regulations and can be harmonized among the HELENA European partners.

Design and implementation of the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study

To provide an overview of the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS) design, with particular attention to its quality control procedures. Other important methodological aspects are described in detail throughout this supplement. Description of the HELENA-CSS sampling and recruitment approaches, standardization and harmonization processes, data collection and analysis strategies and quality control activities. The HELENA-CSS is a multi-centre collaborative study conducted in European adolescents located in urban settings. The data management systems, quality assurance monitoring activities, standardized manuals of operating procedures and training and study management are addressed in this paper. Various quality controls to ensure collection of valid and reliable data will be discussed in this supplement, as well as quantitative estimates of measurement error. The great advantage of the HELENA-CSS is the strict standardization of the fieldwork and the blood analyses, which precludes to a great extent the kind of immeasurable confounding bias that often interferes when comparing results from isolated studies.

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

Analysis of several biological markers improves the quality and physiologic comprehension of data obtained in epidemiological nutritional studies. 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. 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. 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. 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.

Socioeconomic questionnaire and clinical assessment in the HELENA Cross-Sectional Study: methodology

Environmental factors such as dietary habits, breastfeeding, socioeconomic conditions and educational factors are strong influences on nutritional and puberty status, physical activity, food choices and their interactions. Several diseases of adulthood seem to be linked to, or to originate from, lifestyle in childhood and adolescence. The aims of this study are to describe birth parameters and socioeconomic factors and to assess clinical status in adolescents aged 13-16 years from 10 European countries participating in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) Cross-Sectional Study (CSS). A self-report questionnaire on the socioeconomic status, a parental questionnaire concerning neonatal period and also a case report form (CRF), in which clinical items during clinical examination (such as medical history, treatments, anthropometry, Tanner staging, blood pressure, heart rate) were assessed. To develop these documents, first a list of items was established, a search of existing documents was performed and the advice of local and international experts was taken. All documents (questionnaires and an operations manual) were discussed in plenary HELENA meetings; a final version of these documents was fixed, and the process of translation and back translation was performed. The questionnaires and CRF were tested for validation in all 10 participant cities; 208 adolescents were enrolled during the pilot study. All items that caused problems or questions in one or more participating centers or were completed by < 85% of the adolescents were reviewed before the beginning of the HELENA-CSS. These final questionnaires and CRF will contribute to better understanding of the inequalities in nutrition, behavior and health in the European adolescent population. The experience and process should be useful for other multicenter studies.

Food and nutrient intake, nutritional knowledge and diet-related attitudes in European adolescents

To provide an overview of methods used to assess food and nutrient intake, nutritional knowledge and diet-related attitudes in the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS), with selected results from the feasibility study. To assess food intake in 13- to 16-year-old adolescents, a previously developed computer-assisted and self-administered 24-h recall was adapted for international use. Food consumption data were linked to national food composition databases to calculate energy and nutrient intakes. To assess nutritional knowledge in pupils not having any special (trained) education concerning 'nutrition', a 23-item validated multiple choice questionnaire was adapted. To assess eating attitudes, behaviour and/or putative problems with body weight in adolescents, a validated inventory covering 60 questions or statements was adapted for the study. In a feasibility study, instruments, data collection and processing were tested in one school class in each of the 10 participating European cities. The feasibility study provided plausible results, quite consistent between countries. Against this background and for the first time, standardized and uniform methodology was made available for the main study to assess and characterize dietary intake, nutritional knowledge and eating attitudes.