Fruit and vegetables consumption is associated with higher vitamin intake and blood vitamin status among European adolescents.

BACKGROUND/OBJECTIVES: Current research in adults indicates that fruit and vegetable (FAV) consumption increases serum levels of vitamins C, E and folate of ß-carotene and reduces homocysteine concentrations. The aim of the present study was to examine the association of FAV consumption on vitamin intakes and their impact on blood vitamin concentrations in European adolescents. SUBJECT/METHODS: This multi-center cross-sectional study included 702 (53.7% females) adolescents, aged 12.50-17.49 years, from 10 European cities. Two independent self-administered 24 h dietary recalls were used to estimate the adolescent's diet. The total energy, vitamins and FAV consumption were calculated. Adolescents were categorized into three groups: (i) very low FAV intake (<200 g/day); (ii) low FAV consumption (200-399 g/day) and (iii) adequate FAV consumption (⩾400 g/day). Adolescent's fasted blood samples were taken for their analysis on vitamin concentrations. RESULTS: The main results showed that those adolescents meeting the FAV recommendation, classified as FAV adequate consumers, presented higher intake of energy and some vitamins as B6, total folic acid, C, E and ß-carotene compared with FAV very low consumers (P<0.05). Regarding their blood status, male adolescents who had a very low FAV consumption presented lower plasma folate, RBC folate blood concentrations compared with adequate FAV consumers (P<0.05). Female adequate FAV consumers had higher concentrations of pyridoxal phosphate (PLP), plasma folate, RBC folate, vitamin C, ß-carotene and α-tocopherol compared with very low and low consumers (P<0.05). CONCLUSIONS: Having a FAV dairy intake above 400 g/day is associated with higher vitamin intake and blood vitamin concentrations, especially for antioxidant and B-vitamins concentrations.

Liver enzymes and clustering cardiometabolic risk factors in European adolescents: the HELENA study.

OBJECTIVES: This study aimed to explore the associations of liver biomarkers with cardiometabolic risk factors and their clustering, and to provide reference values (percentiles) and cut-off points for liver biomarkers associated with high cardiometabolic risk in European adolescents. METHODS: Alanine aminotransferase (ALT), gamma-glutamyltransferase (GGT), aspartate aminotransferase to ALT ratio (AST/ALT), waist circumference, blood pressure, triglycerides, high-density lipoprotein cholesterol and insulin were measured in 1084 adolescents. We computed a continuous cardiometabolic risk score and defined the high cardiometabolic risk. RESULTS: Higher ALT and GGT and lower AST/ALT were associated with adiposity and with the number of adverse cardiometabolic risk factors (Ps < 0.05). Higher GGT and lower AST/ALT were associated with higher cardiometabolic risk score (Ps < 0.001) in males and females, and ALT only in males (Ps < 0.001). Gender- and age-specific percentiles for liver biomarkers were provided. Receiver operating characteristic analyses showed a significant discriminatory accuracy of AST/ALT in identifying the low/high cardiometabolic risk (Ps < 0.01) and thresholds were provided. CONCLUSIONS: Higher GGT and lower AST/ALT are associated with higher cardiometabolic risk factors and their clustering in male and female European adolescents, whereas the associations of ALT were gender dependent. Our results suggest the usefulness of AST/ALT as a screening test in the assessment of adolescents with high cardiometabolic risk and provide gender- and age-specific thresholds that might be of clinical interest.

Mechanisms of stress, energy homeostasis and insulin resistance in European adolescents--the HELENA study.

BACKGROUND AND AIMS: Stress is hypothesized to facilitate the development of obesity, whose the foundations are already set during childhood and adolescence. We investigated the relationship between the stress-system, selected mechanisms of energy homeostasis and insulin resistance (IR) in a sample of European adolescents. METHODS AND RESULTS: Within HELENA-CSS, 723 adolescents (12.5-17.5 years) from 10 European cities provided all the necessary data for this study. Fasting blood samples were collected for cortisol, leptin, insulin and glucose analysis. HOMA-IR was calculated from insulin and glucose concentrations. Adolescents' body fat (BF) %, age and duration of exclusive breastfeeding were assessed. For boys and girls separately, the relationship of cortisol with leptin, insulin, glucose and HOMA-IR was examined by computing Pearson correlation coefficients and Hierarchical Linear Models (HLMs), with 'city' as cluster unit, adjusting for age, BF% and duration of exclusive breastfeeding. In boys, Pearson correlation coefficients illustrated positive correlations of cortisol with insulin (r = 0.144; p = 0.013), glucose (r = 0.315; p < 0.001) and HOMA-IR (r = 0.180; p = 0.002), whilst in girls, this positive relationship was observed for leptin (r = 0.147; p = 0.002), insulin (r = 0.095; p = 0.050) and HOMA-IR (r = 0.099; p = 0.041), but not for glucose (r = 0.054; p = 0.265). Observed associations were independent of adolescents' age, BF% and duration of exclusive breastfeeding after computing HLMs. CONCLUSION: This study suggests that the stress-system is positively related to mechanisms of energy homeostasis and IR in European adolescents, and reveals a potential small gender difference in this relationship. The hypothesis that stress might facilitate the development of obesity during adolescence is supported.

Combined influence of healthy diet and active lifestyle on cardiovascular disease risk factors in adolescents.

To investigate the combined influence of diet quality and physical activity on cardiovascular disease (CVD) risk factors in adolescents, adolescents (n = 1513; 12.5-17.5 years) participating in the Healthy Lifestyle in Europe by Nutrition in Adolescence study were studied. Dietary intake was registered using a 24-h recall and a diet quality index was calculated. Physical activity was assessed by accelerometry. Lifestyle groups were computed as: healthy diet and active, unhealthy diet but active, healthy diet but inactive, and unhealthy diet and inactive. CVD risk factor measurements included cardiorespiratory fitness, adiposity indicators, blood lipid profile, blood pressure, and insulin resistance. A CVD risk score was computed. The healthy diet and active group had a healthier cardiorespiratory profile, fat mass index (FMI), triglycerides, and high-density lipoprotein cholesterol (HDL-C) levels and total cholesterol (TC)/HDL-C ratio (all P ≤ 0.05). Overall, active adolescents showed higher cardiorespiratory fitness, lower FMI, TC/HDL-C ratio, and homeostasis model assessment index and healthier blood pressure than their inactive peers with either healthy or unhealthy diet (all P ≤ 0.05). Healthy diet and active group had healthier CVD risk score compared with the inactive groups (all P ≤ 0.02). Thus, a combination of healthy diet and active lifestyle is associated with decreased CVD risk in adolescents. Moreover, an active lifestyle may reduce the adverse consequences of an unhealthy diet.

Cardiorespiratory fitness in males, and upper limbs muscular strength in females, are positively related with 25-hydroxyvitamin D plasma concentrations in European adolescents: the HELENA study.

BACKGROUND: High prevalence of vitamin D insufficiency (<75 nmol/l) has been previously reported in European adolescents. Vitamin D deficiency has been related to physical fitness and adiposity but it is not clearly known whether this relationship applies to growing children and adolescents. AIM: To determine how body composition and physical fitness are related to 25-hydroxyvitamin D [25(OH)D] concentrations in European adolescents. DESIGN: The HEalthy Lifestyle in Europe by Nutrition in Adolescence-CSS study was a multi-centre cross-sectional study. METHODS: Plasma 25(OH)D, body composition and physical fitness measures were obtained in 1006 European adolescents (470 males) aged 12.5-17.5 years. Stepwise regression and ANCOVA were performed by gender using 25(OH)D as dependent variable, with body composition, physical fitness as independent variables controlling for age, seasonality and latitude. RESULTS: For males, maximum oxygen consumption (VO2max) (B = 0.189) and body mass index (BMI) (B = -0.124) were independently associated with 25(OH)D concentrations (both P < 0.05). For females, handgrip strength (B = 0.168; P < 0.01) was independently associated with 25(OH)D concentrations. Those adolescents at lower BMI and high fitness score presented significant higher 25(OH)D concentrations than those at lower fitness score in the other BMI groups (P < 0.05). CONCLUSION: Cardiorespiratory fitness and upper limbs muscular strength are positively associated with 25(OH)D concentrations in male and female adolescents, respectively. Adiposity in males and low fat free mass in females are related to hypovitaminosis D. The interaction between fitness and BMI has a positive effect on 25(OH)D concentrations. Therapeutic interventions to correct the high rates of vitamin D deficiency in adolescents should consider physical fitness.

Evaluation of food and nutrient intake assessment using concentration biomarkers in European adolescents from the Healthy Lifestyle in Europe by Nutrition in Adolescence study.

Accurate food and nutrient intake assessment is essential for investigating diet-disease relationships. In the present study, food and nutrient intake assessment among European adolescents using 24 h recalls (mean of two recalls) and a FFQ (separately and the combination of both) were evaluated using concentration biomarkers. Biomarkers included were vitamin C, ß-carotene, DHA+EPA, vitamin B12 (cobalamin and holo-transcobalamin) and folate (erythrocyte folate and plasma folate). For the evaluation of the food intake assessment 390 adolescents were included, while 697 were included for the nutrient intake assessment evaluation. Spearman rank and Pearson correlations, and validity coefficients, which are correlations between intake estimated and habitual true intake, were calculated. Correlations were higher between frequency of food consumption (from the FFQ) and concentration biomarkers than between mean food intake (from the recalls) and concentration biomarkers, especially for DHA+EPA (r 0·35 v. r 0·27). Most correlations were higher among girls than boys. For boys, the highest validity coefficients were found for frequency of fruit consumption (0·88) and for DHA+EPA biomarker (0·71). In girls, the highest validity coefficients were found for fruit consumption frequency (0·76), vegetable consumption frequency (0·74), mean fruit intake (0·90) and DHA+EPA biomarker (0·69). After exclusion of underreporters, correlations slightly improved. Correlations between usual food intakes, adjusted for food consumption frequency, and concentration biomarkers were higher than correlations between mean food intakes and concentration biomarkers. In conclusion, two non-consecutive 24 h recalls in combination with a FFQ seem to be appropriate to rank subjects according to their usual food intake.

Physical activity attenuates the negative effect of low birth weight on leptin levels in European adolescents; the HELENA study.

We examined whether physical activity (PA) influences the association between birth weight and serum leptin in adolescents. The study comprised a total of 538 adolescents (315 girls), aged 12.5-17.49 years, born at term (≥ 37 weeks of gestation). We measured serum leptin levels and time engaged in moderate-vigorous PA (MVPA) by accelerometry. There was an interaction effect between birth weight and meeting the PA recommendations (60 min/day MVPA) on leptin levels in girls (P = 0.023) but not in boys (P = 0.809). Birth weight was negatively associated with leptin levels in girls not meeting the PA recommendations (i.e. more than 60 min/day of MVPA) (ß = -0.096, P = 0.009), whereas no significant association was observed in those meeting the PA recommendations (ß = -0.061, P = 0.433). In conclusion, meeting the PA recommendations may attenuate the negative effect of low birth weight on serum leptin levels in European female adolescents.

Lipid, lipoprotein and apolipoprotein profiles in European adolescents and its associations with gender, biological maturity and body fat--the HELENA Study.

BACKGROUND/OBJECTIVES: To provide a detailed lipid profile of a European adolescent population considering age, gender, biological maturity, body mass index (BMI), fat mass (FM) and percentage body fat (BF). SUBJECTS/METHODS: Within Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA), a cross-sectional study was conducted to determine fasting serum concentrations of lipids, lipoproteins and apolipoproteins in 1076 adolescents aged 12.5-17.49 years from ten European centres. RESULTS: All serum lipid concentrations were significantly higher in girls than in boys. In boys, age was negatively correlated with high-density lipoprotein (HDL)-cholesterol and total cholesterol (TC), and positively associated with triacylglycerides (TAG) (P < 0.01) whereas no significant associations were observed in girls. Biological maturity was negatively associated with TC, HDL-, low-density lipoprotein (LDL)- and non-HDL cholesterol in boys (all P<0.05) and negatively correlated with HDL-cholesterol in girls (P<0.05). BMI, FM and BF were significantly correlated with HDL-cholesterol, LDL-cholesterol, non-HDL cholesterol, apolipoprotein (apo) A1, apoB and TAG in both boys and girls. CONCLUSIONS: The lipid profile in adolescents is strongly determined by gender. Biological maturity, FM and percentage BF contribute to the variance in lipid concentrations and should be considered in future evaluations of lipid status.

Retinol, ß-carotene, α-tocopherol and vitamin D status in European adolescents; regional differences an variability: a review.

Currently, blood levels to define vitamin deficiency or optimal status in adolescents are extrapolated from adults. This may be not adequate as vitamin requirements during adolescence depend on the process of sexual maturation, rapid increasing height and weight, among other factors. In order to establish the state of the art, Medline database (www.ncvi.nlm.nih.gov) was searched for studies published in Europe between 1981 and 2010 related to liposoluble vitamin status in adolescents. A comparison of the vitamin status published in the reviewed articles was difficult due to the lack of studies, lack of consensus on cut-off levels indicating deficiency and optimal vitamin levels and the different age-ranges used. In spite of that, deficiency prevalence varied for vitamin D (13-72%), vitamin A (3%), E (25%) and ß-carotene (14-19%). Additional factors were considered as possible determinants. We conclude that it is necessary to establish a consensus on acceptable ranges and cut-offs of these vitamins during adolescence. Representative data are still missing; therefore, there is a high need to get deeper into the investigation on liposoluble vitamins in this population group.

Retinol, β-carotene, α-tocopherol and vitamin D status in Europeanadolescents; regional differences an variability: A review / Estado de retinol, β-caroteno, α-tocopherol y vitamina D en adolescentes europeos; diferencias regionales y variabilidad: revisión

Currently, blood levels to define vitamin deficiency or optimal status in adolescents are extrapolated from adults. This may be not adequate as vitamin requirements during adolescence depend on the process of sexual maturation, rapid increasing height and weight, among other factors. In order to establish the state of the art, Medline database (www.ncvi.nlm.nih.gov) was searched for studies published in Europe between 1981 and 2010related to liposoluble vitamin status in adolescents. A comparison of the vitamin status published in there viewed articles was difficult due to the lack of studies, lack of consensus on cut-off levels indicating deficiency and optimal vitamin levels and the different age-ranges used. In spite of that, deficiency prevalence varied for vitamin D (13-72%), vitamin A (3%), E (25%) and β-carotene (14-19%). Additional factors were considered as possible determinants. We conclude that it is necessary to establish a consensus on acceptable ranges and cut-offs of these vitamins during adolescence. Representative data are still missing; therefore, there is a high need to get deeper into the investigation on liposoluble vitamins in this population group (AU)

En la actualidad, los diferentes valores sanguíneos que definen un estado óptimo o deficiente de vitaminas liposolubles en los adolescentes son extrapolados de los adultos. Sin embargo, podría no ser lo adecuado debido a que los requerimientos vitamínicos de los adolescentes están marcados por el proceso de maduración sexual y crecimiento entre otros factores. Para establecer el punto de partida, la base de datos Medline (www.ncvi.nlm.nih.gov) ha sido el medio utilizado para la búsqueda de los estudios publicados sobre el estado en vitaminas liposolubles en adolescentes europeos entre los años 1981 y 2010. Compararlos diferentes resultados obtenidos en los diferentes estudios fue difícil debido a la carencia de estudios, a la falta de consenso en los puntos de corte que indican deficiencia y estado óptimo y a los diferentes rangos de edad utilizados. A pesar de esto, en función de los estudios, se observa una variabilidad en la prevalencia de deficiencia de vitamina D (13-72%), vitamina A (3%), E (25%) y β-caroteno (14-19%). Otros factores adicionales fueron considerados como posibles determinantes del estado vitamínico. Se identifica la necesidad de establecer un consenso sobre los rangos aceptables y puntos de corte de estas vitaminas para este grupo de población y profundizar en la investigación de las vitaminas liposolubles en el periodo de la adolescencia (AU)

Is liver transaminases assessment an appropriate tool for the screening of non-alcoholic fatty liver disease in at risk obese children and adolescents? / ¿Es útil la valoración de las transaminasas hepáticas para el screening del hígado graso no alcohólico en niños y adolescentes obesos?

Pediatric obesity has increased dramatically all over the world and nonalcoholic fatty liver disease (NAFLD) is one of the most frequent complications associated with excess adiposity. NAFLD causes serum transaminase elevation and liver disease, which could end up in fibrosis, cirrhosis and eventually hepatocellular carcinoma. NAFLD seems to be associated with the metabolic complications of obesity, mainly insulin resistance. The aim of the present article is to review the role of serum liver enzyme assessment as a suitable non invasive predictor of NAFLD in children. Although serum liver enzyme elevation does not accurately measure liver damage, it may be a valuable and non invasive test to screen NAFLD in children and adolescents and a marker to control NAFLD evolution. To detect NAFLD in obese children and adolescents, transaminases serum concentrations should be routinely determined in these patients. In this sense, it seems necessary to obtain transaminase reference standards for children and adolescents (AU)

La prevalencia de obesidad en niños ha aumentado considerablemente en todo el mundo y el hígado graso no alcohólico (HGNA) es una de las complicaciones más frecuentemente asociadas al exceso de adiposidad. El HGNA provoca elevación de las transaminasas hepáticas y una alteración hepática que pueden desencadenar fibrosis, cirrosis e incluso malignización. El HGNA aparece asociado a las complicaciones metabólicas de la obesidad, sobre todo a la resistencia a la insulina. El objetivo del presente artículo es revisar el rol que tienen las enzimas hepáticas como predictor no invasivo del HGNA en niños. Aunque la elevación de las enzimas hepáticas no valora con exactitud el daño hepático, pueden suponer un test no invasivo para el screening del HGNA en niños y adolescentes y un marcador de su evolución. Las transaminasas hepáticas deben ser determinadas de rutina en el diagnóstico del HGNA en niños y adolescentes. En este sentido, parece necesario encontrar unos estándares de referencia para los niveles de transaminasas en niños y adolescentes (AU)

Is liver transaminases assessment an appropriate tool for the screening of non-alcoholic fatty liver disease in at risk obese children and adolescents?

Pediatric obesity has increased dramatically all over the world and nonalcoholic fatty liver disease (NAFLD) is one of the most frequent complications associated with excess adiposity. NAFLD causes serum transaminase elevation and liver disease, which could end up in fibrosis, cirrhosis and eventually hepatocellular carcinoma. NAFLD seems to be associated with the metabolic complications of obesity, mainly insulin resistance. The aim of the present article is to review the role of serum liver enzyme assessment as a suitable non invasive predictor of NAFLD in children. Although serum liver enzyme elevation does not accurately measure liver damage, it may be a valuable and non invasive test to screen NAFLD in children and adolescents and a marker to control NAFLD evolution. To detect NAFLD in obese children and adolescents, transaminases serum concentrations should be routinely determined in these patients. In this sense, it seems necessary to obtain transaminase reference standards for children and adolescents.

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

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