Marcela González-Gross

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

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

Vitamin D deficiency in Europe: pandemic?

Background: Vitamin D deficiency has been described as being pandemic, but serum 25-hydroxyvitamin D [25(OH)D] distribution data for the European Union are of very variable quality. The NIH-led international Vitamin D Standardization Program (VDSP) has developed protocols for standardizing existing 25(OH)D values from national health/nutrition surveys. Objective: This study applied VDSP protocols to serum 25(OH)D data from representative childhood/teenage and adult/older adult European populations, representing a sizable geographical footprint, to better quantify the prevalence of vitamin D deficiency in Europe. Design: The VDSP protocols were applied in 14 population studies [reanalysis of subsets of serum 25(OH)D in 11 studies and complete analysis of all samples from 3 studies that had not previously measured it] by using certified liquid chromatography–tandem mass spectrometry on biobanked sera. These data were combined with standardized serum 25(OH)D data from 4 previously standardized studies (for a total n = 55,844). Prevalence estimates of vitamin D deficiency [using various serum 25(OH)D thresholds] were generated on the basis of standardized 25(OH)D data. Results: An overall pooled estimate, irrespective of age group, ethnic mix, and latitude of study populations, showed that 13.0% of the 55,844 European individuals had serum 25(OH)D concentrations <30 nmol/L on average in the year, with 17.7% and 8.3% in those sampled during the extended winter (October–March) and summer (April–November) periods, respectively. According to an alternate suggested definition of vitamin D deficiency (<50 nmol/L), the prevalence was 40.4%. Dark-skinned ethnic subgroups had much higher (3- to 71-fold) prevalence of serum 25(OH)D <30 nmol/L than did white populations. Conclusions: Vitamin D deficiency is evident throughout the European population at prevalence rates that are concerning and that require action from a public health perspective. What direction these strategies take will depend on European policy but should aim to ensure vitamin D intakes that are protective against vitamin D deficiency in the majority of the European population.

Influence of socioeconomic factors on fitness and fatness in Spanish adolescents: The AVENA study

OBJECTIVE This study was to examine the influence of socioeconomic status on fitness and fatness in Spanish adolescents. SUBJECTS AND METHODS A total of 1 795 adolescents (833 boys) aged 12.5-18.5 years from the AVENA study participated in this study. The following physical fitness components were assessed: muscular strength (standing long jump), speed-agility (4 × 10 m shuttle run) and cardiorespiratory fitness (20 m shuttle run). Total and central body fat was assessed using skinfold thickness and waist circumference, respectively. Both parents reported their educational and professional level. RESULTS Girls with higher paternal educational level and boys with higher either maternal or paternal professional level had higher muscular strength levels (all P<0.05). Speed-agility and cardiorespiratory fitness were not associated with parental educational or professional levels in boys. In contrast, girls with higher paternal educational level or higher parental professional level had higher levels in both fitness components (all P<0.05). A higher maternal educational level was associated with lower total and central body fat in boys (all P<0.05), but not in girls. We observed a small effect size (Cohens d∼0.2) in most of these associations. CONCLUSIONS Our results suggest modest associations of high socioeconomic status with better fitness and fatness levels in Spanish adolescents. These associations greatly depend on the socioeconomic status and fitness parameters studied.

Muscular and cardiorespiratory fitness are independently associated with metabolic risk in adolescents: the HELENA study

Artero EG, Ruiz JR, Ortega FB, España‐Romero V, Vicente‐Rodríguez G, Molnar D, Gottrand F, González‐Gross M, Breidenassel C, Moreno LA, Gutiérrez A; on behalf of the HELENA Study Group. Muscular and cardiorespiratory fitness are independently associated with metabolic risk in adolescents: the HELENA study.

Influence of alcohol consumption on immunological status: a review.

The aim of this review is to present and discuss the effect of different levels of alcohol consumption on the immune system. Not only the amount consumed but also the type of alcoholic beverage have to be taken into account in order to determine the consequences on activity, number, distribution, balance, interaction and response of immunocompetent cells. The association between alcohol exposure and the risk of developing an alcohol-related disease is multifactorial. In fact, age, gender, smoking habits, dietary intake and exercise are involved among other factors. The evaluation of the host cellular and humoral immune responses has shown that alcohol may induce some benefits when consumption is moderate. Moreover, those alcoholic beverages that contain antioxidants, such as red wine, could be protectors against immune cell damage. According to the literature consulted, the daily consumption of 10–12 g and 20–24 g of alcohol for women and men, respectively, is considered to be a moderate intake; the type of beverage has been established not to be important when defining moderation. Particular attention is often focused on the U- or J-shaped curve which also suggests that light to moderate drinking produces a protective effect. Such an inverse relationship indicates a reduction of risk for both light and moderate consumers and a higher risk not only for hard drinkers, but also for non-consumers.

Single nucleotide polymorphisms in the FADS gene cluster are associated with delta-5 and delta-6 desaturase activities estimated by serum fatty acid ratios

Genetic variability in the FADS1-FADS2 gene cluster [encoding delta-5 (D5D) and delta-6 (D6D) desaturases] has been associated with plasma long-chain PUFA (LCPUFA) and lipid levels in adults. To better understand these relationships, we further characterized the association between FADS1-FADS2 genetic variability and D5D and D6D activities in adolescents. Thirteen single nucleotide polymorphisms (SNPs) were genotyped in 1,144 European adolescents (mean ± SD age: 14.7 ± 1.4 y). Serum phospholipid fatty acid levels were analyzed using gas chromatography. D5D and D6D activities were estimated from the C20:4n-6/C20:3n-6 and C20:3n-6/C18:2n-6 ratios, respectively. Minor alleles of nine SNPs were associated with higher 18:2n-6 levels (1.9E-18 ≤ P ≤ 6.1E-5), lower C20:4n-6 levels (7.1E-69 ≤ P ≤ 1.2E-12), and lower D5D activity (7.2E-44 ≤ P ≤ 4.4E-5). All haplotypes carrying the rs174546 minor allele were associated with lower D5D activity, suggesting that this SNP is in linkage disequilibrium with a functional SNP within FADS1. In contrast, only the rs968567 minor allele was associated with higher D6D activity (P = 1.5E-6). This finding agrees with an earlier in vitro study showing that the minor allele of rs968567 is associated with a higher FADS2 promoter activity. These results suggest that rare alleles of several SNPs in the FADS gene cluster are associated with higher D6D activity and lower D5D activity in European adolescents.

El perfil lipídico-metabólico en los adolescentes está más influido por la condición física que por la actividad física (estudio AVENA)*

Introduction and objectives. To determine whether the level of physical activity or physical fitness (i.e., aerobic capacity and muscle strength) in Spanish adolescents influences lipid and metabolic profiles. Methods. From a total of 2859 Spanish adolescents (age 13.0-18.5 years) taking part in the Diet and Appraisal of Nutrition State in Adolescents 460 (248 male, 212 female) were randomly selected for blood analysis. Their level of physical activity was determined by questionnaire. Aerobic capacity was assessed using the Course-Navette test. Muscle strength was evaluated using flexed arm. A lipidmetabolic cardiovascular risk index was derived from the levels of triglycerides, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and glucose. Results. No relationship was found between the level of physical activity and lipid‐metabolic index in either sex. In contrast, there was an inverse relationship between the lipid‐metabolic index and aerobic capacity in males (P=.003) after adjustment for physical activity level and muscle strength. In females, a favorable lipid‐metabolic index was associated with greater muscle strength (P=.048) after adjustment for aerobic capacity.

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.

Health-related fitness in adolescents: underweight, and not only overweight, as an influencing factor. The AVENA study

This study investigated differences in health‐related fitness (20‐m shuttle run, handgrip, bent arm hang, standing long jump, shuttle run 4 × 10 m and sit and reach tests) in 2474 Spanish adolescents (1196 boys and 1278 girls; age 13–18.5 years) classed as underweight, normal weight, overweight or obese according to body mass index. Body fat and fat‐free mass were derived from skinfold thickness. The prevalence of underweight was higher than obesity in girls (4.8% vs 3.0%, respectively; P<0.05) and the opposite in boys (3.9% vs 5.8%, respectively; P<0.05). Underweight was associated with a higher performance in the bent arm hang test in girls (P<0.05) and a lower performance in handgrip in both genders (P<0.01) compared with normal weight. Overweight and obese adolescents presented a lower performance in 20‐m shuttle run, bent arm hang, standing long jump and shuttle run 4 × 10 m tests (P<0.001), but a higher performance in handgrip strength (P<0.001) compared with normal weight. In weight‐bearing tests, the association became non‐significant after adjusting for fat mass. In conclusion, not only overweight and obesity but also underweight seem to be determinants of health‐related fitness in adolescents. The associations could be related to differences in body composition.

Beverage consumption among European adolescents in the HELENA study.

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