Influence of parental socio-economic status on diet quality of European adolescents: results from the HELENA study.

Diet quality is influenced by socio-economic and geographical factors. The present study sought to assess whether adolescents' diet quality is affected by their parents' socio-economic status and whether the relationship between these factors is similar in northern and southern Europe. Data collected in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study in eight European countries were analysed. Dietary intake data were recorded via repeated 24 h recalls (using specifically developed HELENA Dietary Intake Assessment Tool software) and converted into an adolescent-specific Diet Quality Index (DQI-AM). Socio-economic status was estimated through parental educational level (Par-Educ-Lev) and parental occupation level (Par-Occ-Lev) as reported by the adolescents in a specific questionnaire. The DQI-AM data were then analysed as a function of Par-Educ-Lev and Par-Occ-Lev in northern European countries (Austria, Belgium, France, Germany and Sweden) and southern European countries (Greece, Italy and Spain). We studied a total of 1768 adolescents (age 14.7 (SD 1.3) years; percentage of girls: 52.8%; 1135 and 633 subjects from northern and southern Europe, respectively). On average, the DQI-AM score was higher in southern Europe than in northern Europe (69.1 (SD 0.1) v. 60.4 (SD 2.8), respectively; P < 0.001; Δ = 12.6%). The DQI was positively correlated with both paternal and maternal Par-Educ-Lev. However, this association was more pronounced in northern Europe than in southern Europe (P interaction = 0.004 for the mother and 0.06 for the father). The DQI was also positively correlated with Par-Occ-Lev (all P trends < 0.01), but this correlation was independent of the geographical area (P interaction = 0.51 for the mother and 0.50 for the father). In conclusion, Par-Educ-Lev and Par-Occ-Lev are associated with diet quality in adolescents in Europe. However, this association differs between northern Europe and southern Europe.

Association between self-reported sleep duration and dietary quality in European adolescents.

Evidence has grown supporting the role for short sleep duration as an independent risk factor for weight gain and obesity. The purpose of the present study was to examine the relationship between sleep duration and dietary quality in European adolescents. The sample consisted of 1522 adolescents (aged 12.5-17.5 years) participating in the European multi-centre cross-sectional 'Healthy Lifestyle in Europe by Nutrition in Adolescence' study. Sleep duration was estimated by a self-reported questionnaire. Dietary intake was assessed by two 24 h recalls. The Diet Quality Index for Adolescents with Meal index (DQI-AM) was used to calculate overall dietary quality, considering the components dietary equilibrium, dietary diversity, dietary quality and a meal index. An average sleep duration of ≥ 9 h was classified as optimal, between 8 and 9 h as borderline insufficient and < 8 h as insufficient. Sleep duration and the DQI-AM score were positively associated (ß = 0.027, r 0.130, P< 0.001). Adolescents with insufficient (62.05 (sd 14.18)) and borderline insufficient sleep (64.25 (sd 12.87)) scored lower on the DQI-AM than adolescents with an optimal sleep duration (64.57 (sd 12.39)) (P< 0.001; P= 0.018). The present study demonstrated in European adolescents that short sleep duration was associated with a lower dietary quality. This supports the hypothesis that the health consequences of insufficient sleep may be mediated by the relationship of insufficient sleep to poor dietary quality.

Validation of the Diet Quality Index for Adolescents by comparison with biomarkers, nutrient and food intakes: the HELENA study.

Food-based dietary guidelines (FBDG) aim to address the nutritional requirements at population level in order to prevent diseases and promote a healthy lifestyle. Diet quality indices can be used to assess the compliance with these FBDG. The present study aimed to investigate whether the newly developed Diet Quality Index for Adolescents (DQI-A) is a good surrogate measure for adherence to FBDG, and whether adherence to these FBDG effectively leads to better nutrient intakes and nutritional biomarkers in adolescents. Participants included 1804 European adolescents who were recruited in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) Study. Dietary intake was assessed by two, non-consecutive 24 h recalls. A DQI-A score, considering the components' dietary quality, diversity and equilibrium, was calculated. Associations between the DQI-A and food and nutrient intakes and blood concentration biomarkers were investigated using multilevel regression analysis corrected for centre, age and sex. DQI-A scores were associated with food intake in the expected direction: positive associations with nutrient-dense food items, such as fruits and vegetables, and inverse associations with energy-dense and low-nutritious foods. On the nutrient level, the DQI-A was positively related to the intake of water, fibre and most minerals and vitamins. No association was found between the DQI-A and total fat intake. Furthermore, a positive association was observed with 25-hydroxyvitamin D, holo-transcobalamin and n-3 fatty acid serum levels. The present study has shown good validity of the DQI-A by confirming the expected associations with food and nutrient intakes and some biomarkers in blood.

Cortisone in hair of elementary school girls and its relationship with childhood stress.

UNLABELLED: Children may be exposed to stressful situations with adverse effects on their physiological and psychological health. As cortisone may be a useful additional biomarker for stress research and as it has been shown to be detectable in human hair, this study measured physiological concentrations of hair cortisone in 223 elementary school girls and explored its relationship with child-reported estimates of stress, more specifically questionnaires on major life events (i.e., Coddington Life Events Scale for Children), emotions (i.e., anger, anxiety, sadness, and happiness), and coping strategies (i.e., emotion- versus problem-focused coping). Cortisone concentrations were positively correlated with the overall life event score for the past 6 months (rho = 0.223, p = 0.004), as well as with the negative event score for this period (rho = 0.227, p = 0.003; N = 165). Cortisone did not correlate with emotions or coping styles reported by the children. CONCLUSION: Despite its exploratory nature, this study may suggest elevated hair cortisone concentrations under psychosocial stress in young children. Although the observed findings should be interpreted with prudence, this study may encourage further research elucidating the potential importance and relevance of hair cortisone analysis as an additional or substituting stress biomarker for hair cortisol.

European adolescents' level of perceived stress is inversely related to their diet quality: the Healthy Lifestyle in Europe by Nutrition in Adolescence study.

As stress is hypothesised to influence dietary behaviour, the relationship between perceived stress and diet quality in European adolescents was investigated. Within the Healthy Lifestyle in Europe by Nutrition in Adolescence study, adolescents (n 704, aged 12-17 years) from schools in five European cities (Ghent, Stockholm, Zaragoza, Athens and Vienna) completed a 2 d 24 h dietary recall assessment and an Adolescent Stress Questionnaire. Measurements and information were taken on height, weight, pubertal stage, parental education level, the level of moderate-to-vigorous physical activity (MVPA) and sleep duration. The Diet Quality Index for Adolescents (DQI-A) was calculated from the dietary data, which comprised three components reflecting dietary diversity, quality and equilibrium. Hierarchical linear models were performed to investigate the relationship between the adolescents' level of perceived stress and the DQI-A and its components, adjusting for relevant covariates (age, BMI z-score, pubertal stage and parental education). These models were additionally adjusted for MVPA or sleep duration. In both boys and girls, perceived stress was a significant independent negative predictor for their overall DQI-A. This inverse relationship was observed for all dietary components, except for dietary diversity in boys, and it was unaltered when additionally adjusted for MVPA or sleep duration. The observed inverse relationship between stress and diet quality within these European adolescents supports the hypothesis that stress influences dietary behaviour, thus emphasising the need for preventive stress-coping strategies for adolescents.

Dietary fatty acid intake, its food sources and determinants in European adolescents: the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study.

Dietary fatty acids (FA) play a role in several (patho)physiological processes at any age, and different FA have different effects on lipid status and health outcome. The present study aims to describe the FA intake and its main food sources in a population of healthy European adolescents and to assess the variation in intake as a function of non-dietary factors. FA intake was assessed with 24 h recall interviews in 1804 adolescents aged 12·5-17·5 years. Usual intakes were calculated using the multiple source method. Multilevel analyses, adjusting for study centre, were used to investigate the influence of non-dietary factors. The mean total fat intake was 33·3 (sd 1·2) % of total energy intake (%E). The mean SFA intake was 13·8 (sd 1·2) %E, with 99·8 % of the population exceeding the recommendations. SFA was mainly delivered by meat and cake, pies and biscuits. In most adolescents, the PUFA intake was too low, and 35·5 % of the population did not achieve the minimum recommended intake for α-linolenic acid (ALA). The main determinants of FA intake in the present study population were age and sex, as well as physical activity in the male subgroup. No contributions of body composition, socio-economic status or sexual maturation to the variance in FA intake were observed. In conclusion, the most important public health concerns regarding FA intake in this adolescent population were the low intake of ALA and the high intake of SFA, mainly seen in the younger-aged boys. In this group the major contributor to SFA was meat.

Epidemiological approaches to measure childhood stress.

The prevalence of childhood stress has repeatedly been shown to be high, with 'parental separation' and 'being bullied at school' as the most frequently reported stressors in the child's everyday life. This is quite alarming as children are most vulnerable to the adverse psychological and physiological health consequences of chronic stress exposure. Despite growing research interest in this field over the last years, literature falls short in providing an overview of methods to adequately assess stress in elementary school children (6-12 years old). This review describes questionnaires and interviews, as well as laboratory measurements of cortisol in biological samples (serum, urine, saliva and hair) as stress assessment methods in children, with the emphasis on epidemiological research settings. Major characteristics, strengths and limitations of these methods are established, examples of child-specific stressor questionnaires and interviews are provided and specific recommendations with respect to epidemiological research are formulated. In addition, hair cortisol as a potential biomarker for chronic stress (in children) is discussed more thoroughly. This review is meant to serve as a preliminary guide for health researchers new to this research area by reflecting on theoretical and methodological aspects in childhood stress assessment.

Food intake of European adolescents in the light of different food-based dietary guidelines: results of the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study.

OBJECTIVE: Since inadequate food consumption patterns during adolescence are not only linked with the occurrence of obesity in youth but also with the subsequent risk of developing diseases in adulthood, the establishment and maintenance of a healthy diet early in life is of great public health importance. Therefore, the aim of the present study was to describe and evaluate the food consumption of a well-characterized sample of European adolescents against food-based dietary guidelines for the first time. DESIGN: The HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study is a cross-sectional study, whose main objective was to obtain comparable data on a variety of nutritional and health-related parameters in adolescents aged 12·5-17·5 years. SETTING: Ten cities in Europe. SUBJECTS: The initial sample consisted of more than 3000 European adolescents. Among these, 1593 adolescents (54 % female) had sufficient and plausible dietary data on energy and food intakes from two 24 h recalls using the HELENA-DIAT software. RESULTS: Food intake of adolescents in Europe is not optimal compared with the two food-based dietary guidelines, Optimized Mixed Diet and Food Guide Pyramid, examined in this study. Adolescents eat half of the recommended amount of fruit and vegetables and less than two-thirds of the recommended amount of milk (and milk products), but consume much more meat (and meat products), fats and sweets than recommended. However, median total energy intake may be estimated to be nearly in line with the recommendations. CONCLUSION: The results urge the need to improve the dietary habits of adolescents in order to maintain health in later life.

Breakfast habits among European adolescents and their association with sociodemographic factors: the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study.

OBJECTIVE: To describe breakfast habits at food group level in European adolescents and to investigate the associations between these habits and sociodemographic factors. DESIGN: Cross-sectional study. SETTING: Secondary schools from nine European cities participating in the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study. Breakfast habits were assessed twice using a computer-based 24 h dietary recall. Adolescents who consumed breakfast on at least one recall day were classified as 'breakfast consumers' and adolescents who did not have anything for breakfast on either of the two recall days were considered 'breakfast skippers'. A 'breakfast quality index' to describe breakfast quality was created based on the consumption or non-consumption of cereals/cereal products, dairy products and fruits/vegetables. The sociodemographic factors studied were sex, age, region of Europe, maternal and paternal education, family structure and family affluence. SUBJECTS: Adolescents (n 2672, 53 % girls) aged 12-17 years. RESULTS: The majority of the adolescents reported a breakfast that scored poorly on the breakfast quality index. Older adolescents, adolescents from the southern part of Europe and adolescents from families with low socio-economic status were more likely to consume a low-quality breakfast. CONCLUSIONS: The study highlights the need to promote the consumption of a high-quality breakfast among adolescents, particularly in older adolescents, adolescents from southern Europe and adolescents from families with low socio-economic status, in order to improve public health.

European adolescents' level of perceived stress and its relationship with body adiposity--the HELENA Study.

BACKGROUND: Since stress is hypothesized to be involved in the aetiology of obesity, the present study examined the current perception of stress in European adolescents and the association between adolescent perceived stress and their adiposity. METHODS: Observational data from 1121 adolescents aged 12.5-17.5 years from six European cities involved in the Healthy Lifestyle in Europe by Nutrition in Adolescence cross-sectional study, was investigated. The adolescents completed the adolescent stress questionnaire, comprising 10 different stress dimensions. Anthropometric measurements (weight, height, skinfold thicknesses and circumferences) and bioelectrical impedance analysis were performed, and personal characteristics (age, pubertal stage and parental education) were collected. The measures of perceived stress were described for boys and girls separately and gender differences were investigated. Associations between the adolescents' perceived stress and indicators of general (body mass index z-score, sum of skinfold thicknesses and body fat%) and abdominal (waist and hip circumference, and waist/height ratio) adiposity were examined using hierarchical linear models. RESULTS: While girls reported systematically higher levels of stress compared with boys, their stress profiles were similar, with highest levels for school-related stress followed by future uncertainty. Only in girls, perceived stress was significantly associated with increased measures of general and abdominal adiposity. In boys, no relationship between perceived stress and adiposity measures was observed. CONCLUSIONS: School is reported to be an important source of adolescent stress and should be the focus of stress management campaigns. Only in girls, the hypothesis that stress might be involved in the aetiology of obesity during adolescence was supported.

Prevalence of psychosomatic and emotional symptoms in European school-aged children and its relationship with childhood adversities: results from the IDEFICS study.

The prevalence of childhood stress and psychosomatic and emotional symptoms (PES) has increased in parallel, indicating that adverse, stressful circumstances and PES in children might be associated. This study describes the prevalence of PES in European children, aged 4-11 years old, and examines the relationship among PES, negative life events (NLE) and familial or social adversities in the child's life. Parent-reported data on childhood adversities and PES was collected for 4,066 children from 8 European countries, who participated in the follow-up survey of IDEFICS (2009-2010), by means of the 'IDEFICS parental questionnaire'. A modified version of the 'Social Readjustment Rating Scale', the 'KINDL Questionnaire for Measuring Health-Related Quality of Life in Children and Adolescents' and the 'Strengths and Difficulties Questionnaire' were incorporated in this questionnaire, as well as questions on socio-demographics, family lifestyle and health of the child. Chi-square analyses were performed to investigate the prevalence of PES among survey centres, age groups and sex of the child. Odds ratios were calculated to examine the childhood adversity exposure between PES groups and logistic regression analyses were conducted to investigate: (a) the contribution of the number and (b) the specific types of experienced adversities on the occurrence of PES. 45.7% of the children experienced at least one PES, with low emotional well-being during the last week being most frequently reported (38.2%). No sex differences were shown for the prevalence of PES (P = 0.282), but prevalence proportions rose with increasing age (P < 0.001). Children with PES were more frequently exposed to childhood adversities compared to children without PES (e.g. 13.3 and 3.9% of peer problems and 25.4 and 17.4% of non-traditional family structure in the PES vs. no PES group, respectively, P < 0.001). An increasing number of adversities (regardless of their nature) was found to gradually amplify the risk for PES (OR = 2.85, 95% CI = 1.98-4.12 for a number of ≥3 NLE), indicating the effect of cumulative stress. Finally, a number of specified adversities were identified as apparent risk factors for the occurrence of PES, such as living in a non-traditional family structure (OR = 1.52, 95% CI = 1.30-1.79) or experiencing peer problems (OR = 3.55, 95% CI = 2.73-4.61). Childhood adversities were significantly related to PES prevalence, both quantitatively (i.e. the number of adversities) and qualitatively (i.e. the type of adversity). This study demonstrates the importance and the impact of the child's family and social context on the occurrence of PES in children younger than 12 years old.

Reliability and validity of the Adolescent Stress Questionnaire in a sample of European adolescents--the HELENA study.

BACKGROUND: Since stress is hypothesized to play a role in the etiology of obesity during adolescence, research on associations between adolescent stress and obesity-related parameters and behaviours is essential. Due to lack of a well-established recent stress checklist for use in European adolescents, the study investigated the reliability and validity of the Adolescent Stress Questionnaire (ASQ) for assessing perceived stress in European adolescents. METHODS: The ASQ was translated into the languages of the participating cities (Ghent, Stockholm, Vienna, Zaragoza, Pecs and Athens) and was implemented within the HELENA cross-sectional study. A total of 1140 European adolescents provided a valid ASQ, comprising 10 component scales, used for internal reliability (Cronbach α) and construct validity (confirmatory factor analysis or CFA). Contributions of socio-demographic (gender, age, pubertal stage, socio-economic status) characteristics to the ASQ score variances were investigated. Two-hundred adolescents also provided valid saliva samples for cortisol analysis to compare with the ASQ scores (criterion validity). Test-retest reliability was investigated using two ASQ assessments from 37 adolescents. RESULTS: Cronbach α-values of the ASQ scales (0.57 to 0.88) demonstrated a moderate internal reliability of the ASQ, and intraclass correlation coefficients (0.45 to 0.84) established an insufficient test-retest reliability of the ASQ. The adolescents' gender (girls had higher stress scores than boys) and pubertal stage (those in a post-pubertal development had higher stress scores than others) significantly contributed to the variance in ASQ scores, while their age and socio-economic status did not. CFA results showed that the original scale construct fitted moderately with the data in our European adolescent population. Only in boys, four out of 10 ASQ scale scores were a significant positive predictor for baseline wake-up salivary cortisol, suggesting a rather poor criterion validity of the ASQ, especially in girls. CONCLUSIONS: In our European adolescent sample, the ASQ had an acceptable internal reliability and construct validity and the adolescents' gender and pubertal stage systematically contributed to the ASQ variance, but its test-retest reliability and criterion validity were rather poor. Overall, the utility of the ASQ for assessing perceived stress in adolescents across Europe is uncertain and some aspects require further examination.

Validity of parent-reported weight and height of preschool children measured at home or estimated without home measurement: a validation study.

BACKGROUND: Parental reports are often used in large-scale surveys to assess children's body mass index (BMI). Therefore, it is important to know to what extent these parental reports are valid and whether it makes a difference if the parents measured their children's weight and height at home or whether they simply estimated these values. The aim of this study is to compare the validity of parent-reported height, weight and BMI values of preschool children (3-7 y-old), when measured at home or estimated by parents without actual measurement. METHODS: The subjects were 297 Belgian preschool children (52.9% male). Participation rate was 73%. A questionnaire including questions about height and weight of the children was completed by the parents. Nurses measured height and weight following standardised procedures. International age- and sex-specific BMI cut-off values were employed to determine categories of weight status and obesity. RESULTS: On the group level, no important differences in accuracy of reported height, weight and BMI were identified between parent-measured or estimated values. However, for all 3 parameters, the correlations between parental reports and nurse measurements were higher in the group of children whose body dimensions were measured by the parents. Sensitivity for underweight and overweight/obesity were respectively 73% and 47% when parents measured their child's height and weight, and 55% and 47% when parents estimated values without measurement. Specificity for underweight and overweight/obesity were respectively 82% and 97% when parents measured the children, and 75% and 93% with parent estimations. CONCLUSIONS: Diagnostic measures were more accurate when parents measured their child's weight and height at home than when those dimensions were based on parental judgements. When parent-reported data on an individual level is used, the accuracy could be improved by encouraging the parents to measure weight and height of their children at home.

Determinants of nutrition knowledge in young and middle-aged Belgian women and the association with their dietary behaviour.

The present study investigated the role of socio-demographic and lifestyle determinants on the nutrition knowledge of Belgian women and the association between their knowledge and dietary behaviour. A total of 803 women, aged 18-39 years, were included in a cross-sectional study and completed a general and nutrition knowledge questionnaire and a 2-day food record. Their height and weight were measured under standardised conditions. Linear regression models showed independent significant associations between the following determinants and the women's nutrition knowledge (in order of importance): educational level, age, kind of occupation, smoking behaviour, and work status. Inconsistent or no associations were found for body mass index, physical activity, living situation, and whether or not they had children. The investigated determinants accounted for 13-14.5% of variance in total nutrition knowledge. A rise in nutrition knowledge was associated with a significant rise in consumption of vegetables and fruit, but no differences were seen for other dietary indicators. Most important determinants of the women's nutrition knowledge were educational level, age and their kind of occupation. Women who had better knowledge of nutrition also exhibited better dietary behaviour, thus underlying the importance of nutrition education for improving dietary behaviour.

Validity of instruction leaflets for parents to measure their child's weight and height at home: results obtained from a randomised controlled trial.

OBJECTIVES: To compare the validity of parent-reported height, weight and body mass index (BMI) values of children (aged 4-10 years), when measured at home by means of newly developed instruction leaflets in comparison with simple estimated parental reports. DESIGN: Randomised controlled trial with control and intervention group using simple randomisation. SETTING: Belgian children and their parents recruited via schools (multistage cluster sampling design). PARTICIPANTS: 164 Belgian children (53% male; participation rate 62%). INTERVENTION: Parents completed a questionnaire including questions about the height and weight of their child. Parents in the intervention group received instruction leaflets to measure their child's weight and height. Classes were randomly allocated to the intervention and control groups. Nurses measured height and weight following standardised procedures up to 2 weeks after parental reports. OUTCOME MEASURES: Weight, height and BMI category of the child were derived from the index measurements and the parental reports. RESULTS: Mean parent-reported weight was slightly more underestimated in the intervention group than in the control group relative to the index weights. However, for all three parameters (weight, height and BMI), correlations between parental reports and nurse measurements were higher in the intervention group. Sensitivity for underweight and overweight/obesity was respectively, 75% and 60% in the intervention group, and 67% and 43% in the control group. Weighed κ for classifying children in the correct BMI category was 0.30 in the control group and was 0.51 in the intervention group. CONCLUSIONS: Although mean parent-reported weight was slightly more underestimated in the intervention than in the control group, correlations were higher and there was considerably less misclassification into valid BMI categories for the intervention group. This pattern suggests that most of the parental deviations from the index measurements were probably due to random errors of measurement and that diagnostic measures could improve by encouraging parents to measure their children's weight and height at home by means of instruction leaflets.

Negative life events, emotions and psychological difficulties as determinants of salivary cortisol in Belgian primary school children.

PURPOSE: This paper describes whether children's life events, emotions and psychological difficulties are related to their salivary cortisol patterns and whether this is different between sexes. METHODS: In 385 children (5-10 years old) participating in the ChiBS study, salivary cortisol samples were collected when waking up, 30 min and 60 min after wake up and in the evening on two consecutive weekdays. Moreover, data on children's life events, emotions and difficulties were collected. Statistical analysis was done separately for boys and girls by multilevel growth curve modelling with adjustments for age, body mass index, socio-economic status and wake up time. RESULTS: In boys and girls with more negative life events during the last three months, the diurnal cortisol slope was steeper (more decline). Boys with higher self-reported happiness showed lower overall, morning and evening cortisol levels. In contrast, the diurnal slope was steeper (more decline) in boys with emotional problems due to higher morning values. In girls, peer problems were associated with lower overall and morning cortisol levels. CONCLUSIONS: Children's salivary cortisol patterns were related to some negative life events, emotions and difficulties, although differently in boys and girls. As such, sex-differences in HPA functioning are already present in young children. Most findings support the upregulation of the cortisol response to stress, although lower morning values were found in the presence of peer problems in girls. Future studies should focus on sex differences, positive emotions and the diurnal cortisol slope.

Children's Body composition and Stress - the ChiBS study: aims, design, methods, population and participation characteristics.

BACKGROUND: The last decades, the prevalence of childhood obesity has increased. Apart from other lifestyle factors, the effect of chronic psychosocial stress on the development of obesity has been recognized. However, more research is needed into the influence of chronic stress on appetite regulation, energy balance and body composition, as well as on the interaction with physical activity/sedentary behavior, diet and sleep in children. In this regard, the ChiBS study (Children's Body composition and Stress) was designed at the Ghent University. Within this paper, we describe the aims, design, methods, participation and population characteristics of the ChiBS study. METHODS: The influence of chronic stress on changes in body composition is investigated over a two-year follow-up period (February-June 2010, 2011 and 2012) in primary-school children between 6 and 12 years old in the city Aalter (Flanders, Belgium).Stress is measured by child- and parent-reported stress-questionnaires, as well as by objective stress biomarkers (serum, salivary and hair cortisol) and heart rate variability. Body composition is evaluated using basic anthropometric measurements and air displacement plethysmography. Additional information on socio-economic status, medical history, physical activity, dietary intake and sleep are obtained by questionnaires, and physical activity by accelerometers. RESULTS: The participation percentage was 68.7% (N = 523/761), with 71.3% of the children willing to participate in the first follow-up survey. Drop-out proportions were highest for serum sampling (12.1%), salivary sampling (8.3%) and heart rate variability measurements (7.4%). DISCUSSION: The ChiBS project is unique in its setting: its standardized and longitudinal approach provides valuable data and new insights into the relationship between stress and changes in body composition in a large cohort of young children. In addition, this study allows an in-depth investigation of the validity of the different methods that were used to assess stress levels in children.

Mineral concentrations in hair of Belgian elementary school girls: reference values and relationship with food consumption frequencies.

Although evidence suggests that hair elements may reflect dietary habits and/or mineral intake, this topic remains controversial. This study therefore presents age-specific reference values for hair concentrations of Ca, Cu, Fe, Na, Mg, P and Zn using the LMS method of Cole, and investigates the relationship between dietary habits (i.e. food consumption frequencies) and hair mineral concentrations in 218 Belgian elementary school girls by reduced rank regression (RRR). Hair minerals were quantitatively determined via inductively coupled plasma-mass spectrometry after microwave-assisted acid digestion of 6-cm long vertex posterior hair samples. The Children's Eating Habits Questionnaire-Food Frequency Questionnaire was used to obtain information on food consumption frequency of 43 food items in the month preceding hair collection. The established reference ranges were in line with data for other childhood or adolescent populations. The retained RRR factors explained 40, 50, 45, 46, 44 and 48 % of the variation of Ca, Cu, Fe, Mg, P and Zn concentrations in hair, respectively. Although this study demonstrated that a large proportion of hair mineral variation may be influenced by food consumption frequencies in elementary school girls, a number of food groups known to be rich sources of minerals did not show a relation with certain hair minerals. Future research should focus on mechanisms and processes involved in mineral incorporation and accumulation in scalp hair, in order to fully understand the importance and influence of diet on hair minerals.

Intercorrelations between serum, salivary, and hair cortisol and child-reported estimates of stress in elementary school girls.

To evaluate the impact of stress on children's well-being, it is important to have valid and reliable stress assessment methods. Nevertheless, selection of an appropriate method for a particular research question may not be straightforward, as there is currently no consensus on a reference method to measure stress in children. This article examined to what extent childhood stress can be estimated accurately by stressor questionnaires (i.e., Coddington life events scale) and biological markers (serum, salivary, and hair cortisol) using the Triads (a triangulation) method in 272 elementary school girls. Salivary cortisol was shown to most accurately indicate true childhood stress for short periods in the past (i.e., last 3 months), whereas hair cortisol may be preferred above salivary measurements for periods more distant and thus for chronic stress assessment. However, applicability should be confirmed in larger and more heterogeneous populations.

Objectively-measured and self-reported physical activity and fitness in relation to inflammatory markers in European adolescents: the HELENA Study.

OBJECTIVE: Atherogenesis involves an inflammatory process that occurs early in life even though clinical symptoms are not observed until adulthood. Two important protective factors for low-grade inflammation may be physical activity (PA) and fitness. We examined the independent associations of objective and subjective measurements of PA and fitness with low-grade inflammation in European adolescents. METHODS: A total of 1045 adolescents, aged from 12.5 to 17.5 years old from 10 European cities, were selected from the HELENA-Cross-Sectional Study. Objectively-measured and self-reported PA variables were obtained by accelerometry and the International PA Questionnaire for Adolescents, respectively. Overall, cardiorespiratory, muscular and motor fitness variables were assessed by standardized field-based fitness tests and the International Fitness Scale. C-reactive protein (CRP), complement factors 3 (C3) and 4 (C4), interleukin-6 and TNF-α inflammatory markers were measured. RESULTS: Objectively-measured vigorous PA was inversely associated with C3 (ß=-0.094, P=0.021) but it did not remain significant after any objective fitness indicator was included in the model. Other objectively measured or self-reported assessments of PA were not significantly associated with inflammatory markers. All objective measures of fitness were inversely associated with CRP, C3 and C4, whereas only self-reported motor fitness remained significantly associated with C3, C4 and TNF-α. All these observations were independent of age, sex, city and body mass index or waist circumference. CONCLUSION: High PA in adolescence may play an indirect role on lessening low-grade inflammation through improvements in fitness.