Cohort-Based Reference Values for Serum Ferritin and Transferrin and Longitudinal Determinants of Iron Status in European Children Aged 3-15 Years.

BACKGROUND: Reference values of ferritin and transferrin for European children do not exist. OBJECTIVE: We aimed to provide sex-, age-, and body mass index (BMI)-specific serum ferritin and transferrin reference percentiles of 3-15-y-old children based on cohort data and to investigate determinants of iron status. METHODS: A total of 3390 ferritin and 3416 transferrin measurements from children residing in 8 European countries participating in the IDEFICS/I.Family cohort (https://www.isrctn.com/ISRCTN62310987) at baseline (W0) and 6 y later (W3) were used to estimate percentiles using the generalized additive model for location, scale and shape. Associations of serum ferritin and transferrin concentrations with total iron intake, total iron intake additionally adjusted for vitamin C intake, and iron from heme sources were investigated separately with adjustment for sex, age, country of residence, parental education, usual energy intake and BMI z-score in regression models using cross-sectional and longitudinal data. RESULTS: The age-specific ferritin and transferrin 5th and 95th reference percentiles ranged from 10.9 to 81.1 µg/L and 2.23 to 3.56 g/L, respectively. A deficient iron status was observed in 3% of children at W0 and 7% of children and adolescents at W3, respectively. At both waves, a higher iron intake from heme sources was positively associated with serum ferritin {W0: ß = 3.21 [95% confidence interval (CI): 0.71, 5.71]; W3: ß = 4.48 [95% CI: 2.09, 6.87]}, that is, children consuming one mg more heme iron had a 3.21 and 4.48 µg/L higher ferritin concentration. Adherence to a mainly vegetarian diet was associated with a lower chance for sufficient serum ferritin cross-sectionally at W3 [odds ratio (OR) 0.40 (95% CI: 0.21, 0.81)] and longitudinally [OR 0.35 (95% CI: 0.15, 0.93)]. CONCLUSIONS: Age-, sex-, and BMI-specific reference percentiles of serum ferritin and transferrin concentrations based on cohort data are provided for European children aged 3-15 y and may be used in clinical practice.

Cross-sectional associations between objectively measured sleep characteristics and body mass index in European children and adolescents.

BACKGROUND: Short sleep duration has been found to be associated with a higher risk for overweight and obesity. However, previous studies have mainly relied on subjective measures of sleep duration and other sleep characteristics (eg quality, timing) have often been neglected. Therefore, we aimed to investigate associations between several, mainly objectively measured sleep characteristics and body mass index (BMI). Further, we aimed to identify distinct sleep subtypes based on these sleep characteristics and to study their association with BMI. METHODS: Children aged 9-16 years participating in the European I.Family study (N = 559, 51.2% girls, 32.9% overweight/obese) wore an accelerometer for one week on their wrist and recorded their daily wake-up and lights-off times in a sleep diary. Information on sleep duration, sleep efficiency and sleep latency was derived. To identify sleep subtypes, we conducted a latent class analysis using all five sleep variables. Associations between single sleep variables, sleep subtype and age- and sex-specific BMI z-score were investigated using linear mixed-effects regression models to accommodate clustering among siblings. RESULTS: No statistically significant associations were observed between the single sleep variables (sleep duration, sleep efficiency, sleep latency, wake-up and lights-off times) and BMI z-score. Four sleep subtypes were identified and children were assigned to one of the groups based on their highest probability for latent group membership: "early birds" (17.5% of the sample), "short sleep duration" (14.7%), "optimal sleep" (47.6%) and "poor sleep quality" (20.2%). Sleep subtype was not associated with BMI z-score. CONCLUSIONS: Using objective sleep data, we did not find convincing evidence for associations between the sleep variables under investigation and BMI.

Weight Status and BMI-Related Traits in Adolescent Friendship Groups and Role of Sociodemographic Factors: The European IDEFICS/I.Family Cohort.

BACKGROUND: During adolescence, health behaviors and weight status are increasingly influenced by friendship and peer networks. This paper examines resemblances in weight-related characteristics and how they differ by sociodemographic factors. METHODS: Over 3,000 friendships were reported by 1,603 adolescents, aged 11-16 years, who participated in the school-based I.Family study in 6 European countries. Each "source child" named 1-10 friends for whom standardized weight-related traits were available in the same survey. The mean value of the friends' traits weighted by time spent together was calculated, and related to the source child's trait. Country, age and sex of the source child, parental education, and immigrant background were considered for confounding and moderation. RESULTS: Source children's z-scores of body fat percent and BMI were positively associated with their friends' characteristics, in particular if they had highly educated parents. Positive associations were also found regarding the frequency of fast-food consumption, impulsivity, screen time, preference for sugar-sweetened foods, and hours spent in sports clubs, in increasing order of effect size. Additionally, correlations were observed between friends' cognitive and school functioning and being bullied. No associations were seen for a preference for high-fat foods, weight concerns, and health-related quality of life. Finally, parental education and immigrant background were associated between friends in all countries except Sweden, where no associations were observed. CONCLUSION: Adolescent friends shared a number of weight-related characteristics. For weight measures per se, positive associations with friends' characteristics were only observed in adolescents with high parental education. Associations regarding energy-balance behaviors and indicators of school-related well-being did not differ by parental education. Parental education and immigrant background correlated positively in friends in most countries showing that social aggregation is already occurring in adolescence. The wide spectrum of friendship associations in weight-related traits and behaviors suggests that health promotion initiatives in adolescents should be directed towards peer groups in both school-related and leisure-time environments. ISRCTN Registry: Pan-European IDEFICS/I.Family children cohort (ID ISRCTN62310987; https://doi.org/10.1186/ISRCTN62310987).

Variations in accelerometry measured physical activity and sedentary time across Europe - harmonized analyses of 47,497 children and adolescents.

BACKGROUND: Levels of physical activity and variation in physical activity and sedentary time by place and person in European children and adolescents are largely unknown. The objective of the study was to assess the variations in objectively measured physical activity and sedentary time in children and adolescents across Europe. METHODS: Six databases were systematically searched to identify pan-European and national data sets on physical activity and sedentary time assessed by the same accelerometer in children (2 to 9.9 years) and adolescents (≥10 to 18 years). We harmonized individual-level data by reprocessing hip-worn raw accelerometer data files from 30 different studies conducted between 1997 and 2014, representing 47,497 individuals (2-18 years) from 18 different European countries. RESULTS: Overall, a maximum of 29% (95% CI: 25, 33) of children and 29% (95% CI: 25, 32) of adolescents were categorized as sufficiently physically active. We observed substantial country- and region-specific differences in physical activity and sedentary time, with lower physical activity levels and prevalence estimates in Southern European countries. Boys were more active and less sedentary in all age-categories. The onset of age-related lowering or leveling-off of physical activity and increase in sedentary time seems to become apparent at around 6 to 7 years of age. CONCLUSIONS: Two third of European children and adolescents are not sufficiently active. Our findings suggest substantial gender-, country- and region-specific differences in physical activity. These results should encourage policymakers, governments, and local and national stakeholders to take action to facilitate an increase in the physical activity levels of young people across Europe.

Emotion-driven impulsiveness but not decision-making ability and cognitive inflexibility predicts weight status in adults.

In this study we aimed to determine whether decision-making ability, cognitive inflexibility and emotion-driven impulsiveness are associated with weight status as expressed by body mass index (BMI), percentage body fat, waist circumference and skinfold thickness in adults from eight different European countries taking part in the I.Family study. The Bechara Gambling Task was used to assess decision-making ability (n = 1717). The Berg Card Sorting Test was used to measure cognitive inflexibility (n = 1509). Lastly, the negative urgency subscale from the UPPS-P Impulsive Behavior Scale was used to measure emotion-driven impulsiveness (n = 4450). Hierarchical regression analyses showed that more emotion-driven impulsiveness was statistically significantly associated with a higher BMI, a higher percentage body fat, and a larger waist circumference in adults, controlling for age, sex, socioeconomic status, country and binge eating; but not with skinfold thickness. Cognitive inflexibility and decision-making ability were not statistically significantly associated with any of the weight status related variables. These results support that impulsivity in response to negative emotions, but not decision-making ability or cognitive inflexibility, is associated with the susceptibility to excessive weight (as indicated by a higher BMI, a higher percentage body fat, and a larger waist circumference). In people behaving impulsively when emotional, focusing on reducing negative affect or improving coping skills is of interest in interventions targeting obesity. CLINICAL TRIAL REGISTRATION: The I.Family study is registered in the ISRCTN registry (ISRCTN62310987) on February 23, 2018.

Use of Nutritional Supplements in Youth with Medicated and Unmedicated Attention-Deficit/Hyperactivity Disorder.

OBJECTIVE: To find out whether use of nutritional supplements (NUS) differs between children and adolescents with attention-deficit/hyperactivity disorder (ADHD; medicated or unmedicated), compared with those without the disorder. METHODS: We used cross-sectional data from the population-based I.Family study conducted between 2013 and 2014 in eight European countries. Parents completed questionnaires and participated in interviews, for example, on health and medical history of their child. Data from 5067 children and adolescents aged 5-17 years were included. Exposures were medicated (with ADHD-approved medication) and unmedicated ADHD. The outcome was the use of NUS, measured by use of any or multiple different NUS. Multivariable logistic regression adjusted for sociodemographics and health determinants was used to find ADHD-depending differences. RESULTS: The study sample comprised 4490 children and adolescents without ADHD and 51 medicated and 76 unmedicated subjects with ADHD. Regarding the use of any NUS, no statistically significant differences were found between children and adolescents without ADHD (18%) and those with medicated (18%) or unmedicated ADHD (22%). However, discrepancies appear when considering multiple use of NUS, not reported for any medicated ADHD subject but remarkably often for unmedicated ADHD subjects (13%), resulting in an adjusted odds ratio of 2.6 (95% confidence interval, 1.2-5.6) when compared with those without ADHD (5%). CONCLUSION: Children and adolescents who were not using medication for treating ADHD potentially took NUS as oral remedies. Given the potential for a delay of indicated treatments and for use of those NUS which have no proven effectiveness, pediatricians should actively explore whether NUS have been used to treat ADHD core symptoms, and families should be informed that the average effect size has to be considered small.

Disordered eating in three different age groups in Cyprus: a comparative cross-sectional study.

OBJECTIVE: The objective of this study was to evaluate disordered eating behaviours (DEBs) in different age groups in a Cypriot non-clinical population sample. STUDY DESIGN: Comparative cross-sectional study. METHOD: A total of 1716 participants from the Cyprus component of the I.Family study completed the Eating Attitudes Test-26 (EAT-26). The EAT-26 score ≥20 was used to define participants at risk for DEBs. Participants were divided according to age: adolescence (12-18 years old), young adulthood (25-45 years old) and middle adulthood (46-60 years old). RESULTS: Mean EAT-26 total scores were higher for middle adulthood men and women compared with the two younger age groups. Young adulthood women had the highest percentage of behavioural symptoms of DEBs: binge eating (35%) and laxatives/diet pills/diuretics (12%) compared with the other age groups. Men and women in young adulthood had the highest percentage of participants with EAT-26 scores ≥20. In logistic regression analysis, age group did not prove a significant predictor of DEB risk in a model adjusting for sex, body mass index and physical activity. CONCLUSION: DEB can present at any age and was not confined to adolescence.

Emotion-driven impulsiveness and snack food consumption of European adolescents: Results from the I.Family study.

We aimed to investigate the association between emotion-driven impulsiveness and snack food consumption in 1039 European adolescents aged 12-18 years. During the cross-sectional examination in 2013/2014, complete information was collected on: emotion-driven impulsiveness (using the negative urgency subscale from the Urgency, Premeditation, Perseverance, Sensation seeking, and Positive urgency (UPPS-P) Impulsive Behaviour Scale) and snacking behaviour operationalised as 1) consumption frequency of daily snacks, 2) consumption frequency of energy-dense snacks (both measured using Food Frequency Questionnaire) and 3) usual energy intake of food consumed per snacking occasion in calories. The latter was measured using online self-administered 24-h dietary recalls and was estimated based on the National Cancer Institute (NCI) Method. Anthropometric variables were measured and BMI z-score (zBMI) calculated. Age, sex, highest education level of the family and country of residence were assessed using a questionnaire. Mixed-effect regression analyses were separately conducted for each snacking behaviour outcome with emotion-driven impulsiveness as the exposure. After controlling for zBMI, age, sex, country and socioeconomic status, emotion-driven impulsiveness was positively associated with daily consumption frequency of snacks (ß = 0.07, 95% Confidence Interval (CI) [0.02, 0.12]) and consumption frequency of energy-dense snacks (ß = 0.25, 95% CI [0.19, 0.31]), but not with usual energy intake of food per snacking (ß = 2.52, 95% CI [-0.55, 5.59]). Adolescents with a stronger emotion-driven impulsiveness tendency reported a higher snacking frequency and specifically more energy-dense snacks, whereas the energy intake of snack food seemed less important. These findings have implications for obesity prevention and treatment as they indicate the importance of targeting emotion-driven impulsiveness as a strategy to avoid excessive snacking.

Bidirectional associations between psychosocial well-being and body mass index in European children: longitudinal findings from the IDEFICS study.

BACKGROUND: The negative impact of childhood overweight on psychosocial well-being has been demonstrated in a number of studies. There is also evidence that psychosocial well-being may influence future overweight. We examined the bidirectional association between childhood overweight and psychosocial well-being in children from a large European cohort. The dual aim was to investigate the chronology of associations between overweight and psychosocial health indicators and the extent to which these associations may be explained by parental education. METHODS: Participants from the IDEFICS study were recruited from eight countries between September 2007 and June 2008 when the children were aged 2 to 9.9 years old. Children and families provided data on lifestyle, psychosocial well-being, and measured anthropometry at baseline and at follow-up 2 years later. This study includes children with weight, height, and psychosocial well-being measurements at both time points (n = 7,831). Psychosocial well-being was measured by the KINDL® and Strengths and Difficulties Questionnaire respectively. The first instrument measures health-related quality of life including emotional well-being, self-esteem, parent relations and social relations while the second measures well-being based on emotional symptoms, conduct problems and peer-related problems. Logistic regression was used for modeling longitudinal associations. RESULTS: Children who were overweight at baseline had increased risk of poor health-related quality of life (odds ratio (OR) = 1.23; 95 % confidence interval (CI):1.03-1.48) measured 2 years later; this association was unidirectional. In contrast to health-related quality of life, poor well-being at baseline was associated with increased risk of overweight (OR = 1.39; 95 % CI:1.03-1.86) at 2 year follow-up; this association was also only observed in one direction. Adjustment for parental education did not change our findings. CONCLUSION: Our findings indicate that the association between overweight and psychosocial well-being may be bidirectional but varies by assessment measures. Future research should further investigate which aspects of psychosocial well-being are most likely to precede overweight and which are more likely to be consequences of overweight.

Are context-specific measures of parental-reported physical activity and sedentary behaviour associated with accelerometer data in 2-9-year-old European children?

OBJECTIVE: The aim of the present study was to investigate if context-specific measures of parental-reported physical activity and sedentary behaviour are associated with objectively measured physical activity and sedentary time in children. DESIGN: Cross-sectional study. SETTING: Seven European countries taking part in the IDEFICS (Identification and Prevention of Dietary- and Lifestyle-induced Health Effects in Children and Infants) study. SUBJECTS: Data were analysed from 2-9-year-old children (n 5982) who provided both parental-reported and accelerometer-derived physical activity/sedentary behaviour measures. Parents reported their children's daily screen-time, weekly sports participation and daily outdoor playtime by means of the Outdoor Playtime Checklist (OPC) and Outdoor Playtime Recall Questions (OPRQ). RESULTS: Sports participation, OPC- and OPRQ-derived outdoor play were positively associated with accelerometer-derived physical activity. Television viewing and computer use were positively associated with accelerometer-derived sedentary time. All parental-reported measures that were significantly associated with accelerometer outcomes explained only a minor part of the variance in accelerometer-derived physical activity or sedentary time. CONCLUSIONS: Parental-reported measures of physical activity and sedentary behaviour are not useful as a proxy for 2-9-year-old children's physical activity and sedentary time. Findings do not preclude the use of context-specific measures but imply that conclusions should be limited to the context-specific behaviours that are actually measured. Depending on the aim of the study, future research should carefully consider the choice of measurements, including the use of subjective or objective measures of the behaviour of interest or a combination of both.

The combination of daily breakfast consumption and optimal breakfast choices in childhood is an important public health message.

The aim of this study was to investigate the association of breakfast consumption with children's diet quality and cardiometabolic risk factors. Study sample consisted of 1558 children aged 4-8 years from Cyprus. Breakfast frequency was assessed through a parental questionnaire. Body mass index (BMI), BMI z-scores, waist circumference, blood lipid profile and blood pressure were examined in relation to breakfast frequency consumption. Habitual breakfast consumers' daily nutrient intake was assessed through a 24-Hour Dietary Recall, according to their breakfast choices. Girls who have breakfast on a daily basis had lower mean BMI and BMI z-score; they were also less likely of having abnormal levels of serum triglycerides, atheromatic index (total cholesterol to high density lipoprotein-cholesterol ratio) and diastolic blood pressure after controlling for several confounding factors. Within regular breakfast consumers, of both boys and girls, those having ready to eat cereals had a superior nutrient intake profile. Daily breakfast consumption along with good breakfast choices is an important public health message for Cypriot children.

A study of the dietary intake of Cypriot children and adolescents aged 6-18 years and the association of mother's educational status and children's weight status on adherence to nutritional recommendations.

BACKGROUND: A balanced diet is fundamental for healthy growth and development of children. The aim of this study was to document and evaluate the dietary intake of Cypriot children aged 6-18 years (y) against recommendations, and to determine whether maternal education and children's weight status are associated with adherence to recommendations. METHODS: The dietary intake of a random sample of 1414 Cypriot children was assessed using a 3-day food diary. Adherence to recommendations was estimated and the association of their mother's education and their own weight status on adherence were explored. RESULTS: A large percentage of children consumed less than the minimum of 45% energy (en) of carbohydrate (18.4%-66.5% in different age groups) and exceeded the recommended intakes of total fat (42.4%-83.8%), saturated fatty acids (90.4%-97.1%) and protein (65.2%-82.7%), while almost all (94.7%-100%) failed to meet the recommended fibre intake. Additionally, a large proportion of children (27.0%-59.0%) consumed >300 mg/day cholesterol and exceeded the upper limit of sodium (47.5%-78.5%). In children aged 9.0-13.9y, there was a high prevalence of inadequacy for magnesium (85.0%-89.9%), in girls aged 14.0-18.9y, of Vitamin A (25.3%), Vitamin B6 (21.0%) and iron (25.3%) and in boys of the same group, of Vitamin A (35.8%). Children whose mother was more educated were more likely to consume >15%en from protein, Odds Ratio (OR) 1.85 (95% CI:1.13-3.03) for mothers with tertiary education and exceed the consumption of 300 mg/day cholesterol (OR 2.13 (95% CI:1.29-3.50) and OR 1.84 (95% CI:1.09-3.09) for mothers with secondary and tertiary education respectively). Children whose mothers were more educated, were less likely to have Vitamin B1 (p<0.05) and Vitamin B6 intakes below the EAR (p < 0.05 for secondary school and p < 0.001 for College/University) and iron intake below the AI (p < 0.001). Overweight/obese children were more likely to consume >15%en protein (OR 1.85 (95% CI:1.26-2.71) and have a < Adequate Intake of calcium (OR 1.85 (95% CI:1.11-3.06)). CONCLUSION: Cypriot children consume a low quality diet. Maternal education and children's own weight status are associated with children's adherence to recommendations. Public health policies need to be evaluated to improve dietary quality and reduce disease burden.

Physical activity and sedentary behaviour in European children: the IDEFICS study.

OBJECTIVE: To estimate the prevalence of physical activity and sedentary behaviours in European children, and to evaluate the relationship between media availability in personal space and physical activity in relation to total screen time. DESIGN: Data from the baseline IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) cross-sectional survey. Information on hours of television/digital video disk/video viewing and computer/games-console use (weekday and weekend days), media device availability in personal space, sports club membership, hours of active organized play and commuting (to and from school) were assessed via a self-reported parental questionnaire. Total screen time was defined as the sum of daily media use and subsequently dichotomized into meeting or not meeting the guidelines of the American Academy of Pediatrics. SETTING: Eight survey centres (Italy, Estonia, Cyprus, Belgium, Sweden, Germany, Hungary and Spain). SUBJECTS: Children (n 15 330; 51% males) aged 2-10 years. RESULTS: Percentage of children engaged in total screen time for >2 h/d was higher on weekend days (52% v. 20% on weekdays) and in the older group (71% in males; 57% in females), varying by country. Children with a television set in their bedroom were more likely not to meet the screen time recommendations (OR = 1·54; 95% CI 1·60, 1·74). CONCLUSIONS: Approximately a third of the children failed to meet current screen time recommendations. Availability of a television set in personal space increased the risk of excess total screen time. This information could be used to identify potential targets for public health promotion actions of young population groups.

Prevalence of negative life events and chronic adversities in European pre- and primary-school children: results from the IDEFICS study.

BACKGROUND: Children are not always recognized as being susceptible to stress, although childhood stressors may originate from multiple events in their everyday surroundings with negative effects on children's health. METHODS: As there is a lack of large-scale, European prevalence data on childhood adversities, this study presents the prevalence of (1) negative life events and (2) familial and social adversities in 4637 European pre- and primary-school children (4-11 years old), using a parentally-reported questionnaire embedded in the IDEFICS project ('Identification and prevention of Dietary- and lifestyle-induced health EFfects In Children and infantS'). RESULTS: The following findings were observed: (1) Certain adversities occur only rarely, while others are very regular (i.e. parental divorce); (2) A large percentage of children is shielded from stressors, while a small group of children is exposed to multiple, accumulating adversities; (3) The prevalence of childhood adversity is influenced by geographical location (e.g. north versus south), age group and sex; (4) Childhood adversities are associated and co-occur, resulting in potential cumulative childhood stress. CONCLUSIONS: This study demonstrated the importance of not only studying traumatic events but also of focusing on the early familial and social environment in childhood stress research and indicated the importance of recording or monitoring childhood adversities.

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.