Influence of sex, age, pubertal maturation and body mass index on circulating white blood cell counts in healthy European adolescents­the HELENA study.

UNLABELLED: Percentiles 10th, 25th, 50th, 75th and 90th are presented for circulating white blood cells (WBC), neutrophils, lymphocytes, monocytes, eosinophils and basophils in healthy European adolescents (12.5-17.5 years, n = 405, 48.9% boys), considering age, sex, puberty and body mass index (BMI). CD3(+) (mature T cells), CD4(+) (T helper), CD8(+) (T cytotoxic), CD16(+)56(+) (natural killer), CD19(+) (B cells), CD3(+)CD45RA(+), CD4(+)CD45RA(+), CD8(+)CD45RA(+) (naïve), CD3(+)CD45RO(+), CD4(+)CD45RO(+) and CD8(+)CD45RO(+) (memory) lymphocytes were also analysed by immunophenotyping. Girls presented higher WBC, neutrophil, CD3(+)CD45RO(+) and CD4(+)CD45RO(+) cell counts and CD3(+)/CD19(+) ratio, and lower CD3(+)CD45RA(+) and CD4(+)CD45RA(+) counts than boys. Age was associated with higher neutrophil counts and CD3(+)/CD19(+), and lower CD19(+) counts; in boys, with lower CD3(+)CD45RA(+), CD4(+)CD45RA(+) and CD8(+)CD45RA(+) counts as well; in girls, with higher WBC, CD3(+)CD45RO(+) and CD4(+)CD45RO(+) counts. Pubertal maturation in boys was associated with lower WBC and lymphocyte counts; in girls, with higher basophil, CD3(+)CD45RO(+) and CD4(+)CD45RO(+) values. BMI was associated with higher WBC counts; in boys, also with higher lymphocyte counts; in girls, with higher neutrophil, CD4(+), CD3(+)CD45RO(+) and CD4(+)CD45RO(+) counts. CONCLUSION: Our study provides normative values for circulating immune cells in adolescents, highlighting the importance of considering sex, age, pubertal maturation and BMI when establishing reference ranges for WBC in paediatric populations.

More physically active and leaner adolescents have higher energy intake.

OBJECTIVE: To test whether youths who engage in vigorous physical activity are more likely to have lean bodies while ingesting relatively large amounts of energy. For this purpose, we studied the associations of both physical activity and adiposity with energy intake in adolescents. STUDY DESIGN: The study subjects were adolescents who participated in 1 of 2 cross-sectional studies, the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study (n = 1450; mean age, 14.6 years) or the European Youth Heart Study (EYHS; n = 321; mean age, 15.6 years). Physical activity was measured by accelerometry, and energy intake was measured by 24-hour recall. In the HELENA study, body composition was assessed by 2 or more of the following methods: skinfold thickness, bioelectrical impedance analysis, plus dual-energy X-ray absorptiometry or air-displacement plethysmography in a subsample. In the EYHS, body composition was assessed by skinfold thickness. RESULTS: Fat mass was inversely associated with energy intake in both studies and using 4 different measurement methods (P ≤ .006). Overall, fat-free mass was positively associated with energy intake in both studies, yet the results were not consistent across measurement methods in the HELENA study. Vigorous physical activity in the HELENA study (P < .05) and moderate physical activity in the EYHS (P < .01) were positively associated with energy intake. Overall, results remained unchanged after adjustment for potential confounding factors, after mutual adjustment among the main exposures (physical activity and fat mass), and after the elimination of obese subjects, who might tend to underreport energy intake, from the analyses. CONCLUSION: Our data are consistent with the hypothesis that more physically active and leaner adolescents have higher energy intake than less active adolescents with larger amounts of fat mass.

Association of breakfast consumption with objectively measured and self-reported physical activity, sedentary time and physical fitness in European adolescents: the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study.

OBJECTIVE: To examine the association of breakfast consumption with objectively measured and self-reported physical activity, sedentary time and physical fitness. DESIGN: The HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Cross-Sectional Study. Breakfast consumption was assessed by two non-consecutive 24 h recalls and by a 'Food Choices and Preferences' questionnaire. Physical activity, sedentary time and physical fitness components (cardiorespiratory fitness, muscular fitness and speed/agility) were measured and self-reported. Socio-economic status was assessed by questionnaire. SETTING: Ten European cities. SUBJECTS: Adolescents (n 2148; aged 12·5-17·5 years). RESULTS: Breakfast consumption was not associated with measured or self-reported physical activity. However, 24 h recall breakfast consumption was related to measured sedentary time in males and females; although results were not confirmed when using other methods to assess breakfast patterns or sedentary time. Breakfast consumption was not related to muscular fitness and speed/agility in males and females. However, male breakfast consumers had higher cardiorespiratory fitness compared with occasional breakfast consumers and breakfast skippers, while no differences were observed in females. Overall, results were consistent using different methods to assess breakfast consumption or cardiorespiratory fitness (all P ≤ 0·005). In addition, both male and female breakfast skippers (assessed by 24 h recall) were less likely to have high measured cardiorespiratory fitness compared with breakfast consumers (OR = 0·33; 95% CI 0·18, 0·59 and OR = 0·56; 95%CI 0·32, 0·98, respectively). Results persisted across methods. CONCLUSIONS: Skipping breakfast does not seem to be related to physical activity, sedentary time or muscular fitness and speed/agility as physical fitness components in European adolescents; yet it is associated with both measured and self-reported cardiorespiratory fitness, which extends previous findings.