Reference values for leptin, cortisol, insulin and glucose, among European adolescents and their association with adiposity: the HELENA study.

BACKGROUND AND OBJECTIVE: Adequate concentrations of leptin, cortisol, and insulin are important for a suitable metabolism and development during adolescence. These hormones jointly with glucose play a major role in fat metabolism and development of childhood obesity. Our main objective was to quantify biomarkers as leptin, cortisol, insulin and glucose status in European adolescents to contribute to establish reference ranges. METHODS: A representative sample of 927 adolescents (45% males, 14.9±1.2 years for the overall population) from ten European cities of the HELENA study was used to obtain fasting blood samples for these biomarkers. The percentile distributions were computed by sex and age and percentiles were associated with BMI classification. RESULTS: Serum leptin concentration in adolescents varied significantly according to BMI, sex and age (all p < 0.001). Cortisol presented a tendency to increase with age, both for females and males, while insulin and glucose were stable with age. Leptin and insulin were highest in obese adolescents (p < 0.001), whilst cortisol and glucose did not vary with BMI. Percentiles 5, 25, 50, 75 and 95, for hormones values were, respectively: 1.27, 4.06, 11.54, 26.70 and 65.33 ng/ml for leptin; 5.00, 8.11, 11.14, 15.00 and 24.51 µg/dl for cortisol and 3.65, 6.15, 8.52, 11.90 and 20.53 µlU/ml for insulin. CONCLUSIONS: In adolescents, leptin, cortisol, insulin and glucose concentrations are differently affected by age, sex and BMI. Establishment of reference ranges (percentiles) of these biomarkers would be of great interest when pediatricians have to assess the trend of an adolescent to develop obesity years after.

Objetivo: Concentraciones adecuadas de leptina, cortisol e insulina son importantes para un metabolismo normal durante la adolescencia, puesto que valores alterados de estas hormonas, junto con la glucosa, se asocian con el desarrollo de la obesidad infantil. Nuestro principal objetivo fue cuantificar estos marcadores en adolescentes europeos con el fin de establecer rangos de referencia. Métodos: Muestras de sangre procedentes de 927 adolescentes en ayunas (14,9 ± 1,2 años, 45% varones, estudio HELENA), fueron analizadas para cuantificar la leptina, cortisol, insulina y glucosa. Las distribuciones de percentiles se determinaron teniendo en cuenta el sexo y la edad. También se estudió la asociación entre percentiles y la clasificación del IMC. Resultados: La concentración de leptina en suero variaba significativamente con el IMC, el sexo y la edad (todos p.

Reference values for leptin, cortisol, insulin and glucose, among European adolescents and their association with adiposity: The HELENA Study / Valores de referencia para leptina, cortisol, insulina y glucosa entre los adolescentes europeos y su asociación con adiposidad: estudio HELENA

Background and Objective: Adequate concentrations of leptin, cortisol, and insulin are important for a suitable metabolism and development during adolescence. These hormones jointly with glucose play a major role in fat metabolism and development of childhood obesity. Our main objective was to quantify biomarkers as leptin, cortisol, insulin and glucose status in European adolescents to contribute to establish reference ranges. Methods: A representative sample of 927 adolescents (45% males, 14.9±1.2 years for the overall population) from ten European cities of the HELENA study was used to obtain fasting blood samples for these biomarkers. The percentile distributions were computed by sex and age and percentiles were associated with BMI classification. Results: Serum leptin concentration in adolescents varied significantly according to BMI, sex and age (all p<0.001). Cortisol presented a tendency to increase with age, both for females and males, while insulin and gluco- se were stable with age. Leptin and insulin were highest in obese adolescents (p<0.001), whilst cortisol and glucose did not vary with BMI. Percentiles 5, 25, 50, 75 and 95, for hormones values were, respectively: 1.27, 4.06, 11.54, 26.70 and 65.33 ng/ml for leptin; 5.00, 8.11, 11.14, 15.00 and 24.51 µg/dl for cortisol and 3.65, 6.15, 8.52, 11.90 and 20.53 µlU/ml for insulin. Conclusions: In adolescents, leptin, cortisol, insulin and glucose concentrations are differently affected by age, sex and BMI. Establishment of reference ranges (percentiles) of these biomarkers would be of great interest when pediatricians have to assess the trend of an adolescent to develop obesity years after (AU)

Objetivo: Concentraciones adecuadas de leptina, corti- sol e insulina son importantes para un metabolismo normal durante la adolescencia, puesto que valores alterados de estas hormonas, junto con la glucosa, se asocian con el desarrollo de la obesidad infantil. Nuestro principal objetivo fue cuantificar estos marcadores en adolescentes europeos con el fin de establecer rangos de referencia. Métodos: Muestras de sangre procedentes de 927 adolescentes en ayunas (14,9 ± 1,2 años, 45% varones, estudio HELENA), fueron analizadas para cuantificar la leptina, cortisol, insulina y glucosa. Las distribuciones de percentiles se determinaron teniendo en cuenta el sexo y la edad. También se estudió la asociación entre percentiles y la clasificación del IMC. Resultados: La concentración de leptina en suero variaba significativamente con el IMC, el sexo y la edad (todos p<0,001). El cortisol presentó una tendencia a aumentar con la edad, tanto para varones como mujeres, mientras que la insulina y la glucosa eran estables con la edad. La leptina y la insulina fueron más altas en los adolescentesobesos (p <0,001), mientras que el cortisol y glucosa no variaron con el IMC. Los percentiles 5, 25, 50, 75 y 95, para los valores de hormonas fueron, respectivamente: 1.27, 4.06, 11.54, 26.70 y 65.33 ng/ml para la lepti- na; 5.00, 8.11, 11.14, 15.00 y 24.51 µg/dl para el cortisol y 3.65, 6.15, 8.52, 11.90 y 20.53 µlU/ml de insulina. Conclusiones: En los adolescentes, las concentraciones de referencia de leptina, cortisol, insulina y glucosa se ven afectados de manera diferente según la edad, el sexo y el IMC (AU)

Antioxidant vitamin status (A, E, C, and beta-carotene) in European adolescents - the HELENA Study.

BACKGROUND: An adequate nutritional status of antioxidant vitamins (vitamins A, C, E) and b-carotene is essential especially during childhood and adolescence, because of their important roles in cell growth and development. Currently, there are no physiological reference values for blood concentration of these vitamins and b-carotene in apparently healthy European adolescents. The aim of the current study was to obtain reliable and comparable data of antioxidant vitamins and b-carotene in a cross-sectional study, within HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence), which was conducted in a representative sample of adolescents from ten European cities. MATERIAL AND METHODS: From a subsample of 1,054 adolescents (males= 501) of the HELENA Cross Sectional Study with an age range of 12.5 to 17.49 years, fasting blood samples were taken and analyzed for vitamins A, E, C, and b-carotene status. As specific reference values for adolescents are missing, percentile distribution by age and sex is given. RESULTS: Mean concentrations were the following: Retinol: 356.4 ± 107.9 cm/mL; alpha-tocopherol: 9.9 ± 2.1 microg/mL; vitamin C: 10.3 ± 3.3 mg/L; and b-carotene: 245.6 ± 169.6 cm/mL. Females showed higher alpha-tocopherol and vitamin C values compared with males and 17-year-old boys had higher retinol levels than the same-aged girls (p = 0.018). Retinol serum concentrations increased significantly according to age in both gender, but girls had also significantly increasing b-carotene levels by age. CONCLUSIONS: For the first time, concentrations of antioxidant vitamins and pro-vitamin beta-carotene have been obtained in a representative sample of apparently healthy European adolescents. These data can contribute to the establishment of reference ranges in adolescents.

Influence of postharvest processing and storage on the content of phenolic acids and flavonoids in foods.

The review is based on the evaluation of electronically collated data published between 2002 to June 2006. It is based on 325 references dealing with the following subclasses of phenolic compounds: hydroxycinnamic and hydroxybenzoic acids, chalcones, flavanones, flavones, flavonols, monomeric flavanols and anthocyanins. Only publications dealing directly with the effects of storage and postharvest processing on the phenolic acid and flavonoid contents of foods were considered. The expectation that the structural diversity even within each subgroup, and the number of different procedures and of different parameters would make finding homogenous tendencies unlikely, has, in most instances, been confirmed. By adding a database Excel table combined with a focused and unified evaluation, specific additional information was rendered accessible and concise. It holds true for most of the subclasses in question that the effect of storage and food processing on the polyphenol content is negligible in comparison to the differences between different varieties of plants. Variety dependence must always be considered, for all classes of compounds.