Children’s body composition and stress, the ChiBS study : aims, design, methods, population and participation characteristics

BACKGROUND: The last decades, the prevalence of childhood obesity has increased. Apart from other lifestyle factors, the effect of chronic psychosocial stress on the development of obesity has been recognized. However, more research is needed into the influence of chronic stress on appetite regulation, energy balance and body composition, as well as on the interaction with physical activity/sedentary behavior, diet and sleep in children. In this regard, the ChiBS study (Children’s Body composition and Stress) was designed at the Ghent University. Within this paper, we describe the aims, design, methods, participation and population characteristics of the ChiBS study. METHODS: The influence of chronic stress on changes in body composition is investigated over a two-year follow-up period (February-June 2010, 2011 and 2012) in primary-school children between 6 and 12 years old in the city Aalter (Flanders, Belgium). Stress is measured by child- and parent-reported stress-questionnaires, as well as by objective stress biomarkers (serum, salivary and hair cortisol) and heart rate variability. Body composition is evaluated using basic anthropometric measurements and air displacement plethysmography. Additional information on socio-economic status, medical history, physical activity, dietary intake and sleep are obtained by questionnaires, and physical activity by accelerometers. RESULTS: The participation percentage was 68.7% (N = 523/761), with 71.3% of the children willing to participate in the first follow-up survey. Drop-out proportions were highest for serum sampling (12.1%), salivary sampling (8.3%) and heart rate variability measurements (7.4%). DISCUSSION: The ChiBS project is unique in its setting: its standardized and longitudinal approach provides valuable data and new insights into the relationship between stress and changes in body composition in a large cohort of young children. In addition, this study allows an in-depth investigation of the validity of the different methods that were used to assess stress levels in children

Fatty acid status in adolescents: interplay between diet and genes

Both quantity and quality of dietary fatty acid (FA) intake have been associated with several non-communicable diseases in humans, such as cardiovascular disease, cancer, neurologic disorders, inflammatory and auto-immune diseases. Pathophysiologic mechanisms underlying these associations are currently not completely understood. However, through their function as lipid mediator and modulator of gene transcription, FA might interfere in and modulate the disease processes. FA intake is one of the determinants of the FA serum status, which ultimately determines these effects. Other factors, such as the genetic variants of certain genes, sex, body composition, etc, which influence the metabolism of the FA, have been shown to play a role as well. The general aim of this thesis was to further elaborate the current knowledge on the influence of dietary FA intakes and its interaction with polymorphisms in the FADS1 and LIPC gene, on the FA serum status in the healthy population. This insight could help us to identify possible mechanisms to modulate the FA serum status and as such help to prevent or treat the non-communicable diseases, mentioned above. Although most of these diseases usually manifest in adulthood, cardiometabolic risk factors may already appear at younger age and may track into adulthood. As such, this thesis focused on adolescents and was imbedded in the ‘Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study’ (HELENA-CSS), which had as main objective to obtain reliable and comparable data on nutrition- and health-related parameters in a sample of 3528 European adolescents (aged 12.5-17.5 years). In a first study, the usual FA intake and its main food sources were described in this adolescent population and the variation in intake as a function of non-dietary factors, such as sex, age, body composition, sexual maturation, socio-economic status and physical activity was explored. Compared to the recommendations of the Food and Agriculture Organization, almost all adolescents had an excessive intake of saturated fatty acids (SFA) (99.8%) and an inadequate intake of n-3 FA (>50%). In general, girls had a more beneficial FA intake pattern; however, the differences between sexes disappeared in the older aged adolescents (15-17.5 years) except for the poly-unsaturated fatty acid (PUFA) intake, which continued to be higher in the older adolescent female population. Furthermore, chronological age was a stronger determinant of FA intake than sexual maturation and no differences in fat intake were observed as a function of maternal education level or body composition, measured as BMI z-score or body fat percentage. In the male population, fat and fatty acid intake was inversely related to their level of physical activity. The main contributors to total fat, SFA, mono-unsaturated fatty acids (MUFA) and PUFA intake were meat, dairy products and cakes/pies/biscuits. Generally, meat was a slightly higher contributor in boys whilst cakes, pies and biscuits as well as nuts and seeds seemed to be of higher importance in girls. Another study indicated that, although adolescents with a better overall dietary quality had higher levels of total fat intake and SFA than their counterparts with a less beneficial dietary pattern, they derived their fat intake from more recommended food sources. In particular a higher consumption of dairy products and lower consumption of snacks and sauces was observed in adolescents with a Diet Quality Index for Adolescents (DQI-A) score in the upper quartile. In a second study, the influence of specific food intake on the serum phospholipid (PL) FA concentration was investigated by exploring the correlations and the amount of variance that was explained by these nutritional factors. It was demonstrated that the percentage of variation in PL FA serum levels due to dietary intake varied from 14.2% for n-3 FA to 7.0% for total MUFA. For arachidonic acid (AA) and linoleic acid (LA) this was respectively 10.8% and 10.7%. This indicated that dietary intake is indeed a factor of considerable importance on the FA serum status but that other determinants also interfere such as the homeostatic control mechanisms and a wide array of genetic, environmental and life-style factors. In a final study the influence of genetic predisposition on the PL FA serum status was explored. In the HELENA study population it was demonstrated that genetic variability in the rs174546 single nucleotide polymorphism (SNP) of the FADS1 gene, encoding for the Δ5-desaturase, was associated with higher serum PL concentrations of LA and α-linolenic acid (ALA) and lower levels of AA and eicosapentaenoic acid (EPA). In the LIPC gene, the minor allele of the rs1800588, resulting in a lower activity of hepatic lipase, was associated with higher levels of stearic acid. Furthermore, an interaction effect between the rs1800588 SNP and dietary LA intake as well as between this SNP and estimated VO2max on the serum PL AA levels was demonstrated. Overall, these findings indicated that the dietary FA intake influences the FA serum status by its direct effect as source or precursor of certain FA, but that it also exerts an important role by the interaction with certain genes. This interplay between diet and genes demonstrated that individuals with a certain genetic background would require different amounts of individual FA to achieve the same biological effect and thus might benefit from so called “personalized nutrition”. Moreover, it can be concluded that other factors such as the global dietary pattern and the physical activity of an individual are of importance and that it remains essential to further encourage compliance to these general public health guidelines. More specifically, attention should be drawn to higher intakes of n-3 LCPUFA and lower intakes of SFA in adolescent age. Nevertheless, these findings were subject to some limitations, such as the lack of accuracy of the estimated FA intake, the variation in international recommendations, not being able to correct for alcohol intake and smoking habits, the limited comparability to other studies assessing lipid pools other than phospholipids and the limited number of genetic variants that have been analysed. As such, future studies should be extended to the investigation of other polymorphisms in the LIPC and FADS genes as well as to other genes; and the gene-environment effect on hard endpoints, such as the development of the above mentioned diseases, should be assessed. Moreover, in dietary intervention and supplementation studies, genetic variability should be considered. Also, in supplementation studies it should be examined whether pharmaceutical doses of FA may have adverse effects. Ultimately, based on such results we might be able to deduce in what form and combination, as supplement or via the diet, we need to supply these nutrients to obtain maximal health benefit with minimal risk

Blood lipids among young children in Europe : results from the European IDEFICS study

BACKGROUND: Measurement of cholesterol and triglyceride (TG) fractions in blood has become standard practice in the early detection of atherosclerotic disease pathways. Considerable attention is given nowadays to the presence of these risk factors in children and to start preventive campaigns early in life. In this context, it is imperative to have valid comparative frameworks for interpretation of lipid levels. The aim of this study is to present sex-and age-specific reference values on blood lipid levels in European children aged 2.0-10.9 years. METHODS: Fasting blood was obtained via either venipuncture or capillary sampling. In 13 579 European non-obese children (50.3% boys), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), TG and TC/HDL-C ratio levels were measured with a point-of-care analyser (Cholestech). Sex- and age-specific reference values were computed with the GAMLSS method with the statistical software R. RESULTS: Reference curves and 1st, 3rd, 10th, 25th, 50th, 75th, 90th, 97th and 99th percentile values are presented. HDL-C showed a positive trend with age, from 2 years onwards, but was relatively stable above the age of 7. For LDL-C and TC, linear but small age-related trends were seen. The TC/HDL-C values showed a gradual negative trend from the age of 2 up to 6 and were relatively stable afterwards. For TG, no age trend was found (P = 0.285). Boys had higher mean HDL-C values than girls (1.414 vs 1.368 mmol l(-1)), and lower TC, LDL-C, TC/HDL-C and TG values (3.981 vs 4.087 mmol l(-1); 2.297 vs 2.435 mmol l(-1); 2.84 vs 3.01mmol l(-1); and 0.509 vs 0.542 mmol l(-1), respectively). CONCLUSIONS: These new and recent references could serve as a European orientation of blood lipid values in children in the context of standard medical practice and for the purpose of public health screening

Associations between macronutrient intake and serum lipid profile depend on body fat in European adolescents: the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study

The present study aimed to investigate the relationships between macronutrient intake and serum lipid profile in adolescents from eight European cities participating in the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) cross-sectional study (2006–7), and to assess the role of body fat-related variables in these associations. Weight, height, waist circumference, skinfold thicknesses, total choles- terol, HDL-cholesterol (HDL-C), LDL-cholesterol, TAG, apoB and apoA1 were measured in 454 adolescents (44 % boys) aged 12·5–17·5 years. Macronutrient intake (g/4180 kJ per d (1000 kcal per d)) was assessed using two non-consecutive 24 h dietary recalls. Associations were evaluated by multi-level analysis and adjusted for sex, age, maternal education, centre, sum of four skinfolds, moderate-to-vigorous

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

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

Dietary fatty acid intake, its food sources and determinants in European adolescents: the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study

Dietary fatty acids (FA) play a role in several (patho)physiological processes at any age, and different FA have different effects on lipid status and health outcome. The present study aims to describe the FA intake and its main food sources in a population of healthy European adolescents and to assess the variation in intake as a function of non-dietary factors. FA intake was assessed with 24 h recall interviews in 1804 adolescents aged 12·5–17·5 years. Usual intakes were calculated using the multiple source method. Multilevel analyses, adjusting for study centre, were used to investigate the influence of non-dietary factors. The mean total fat intake was 33·3 (sd1·2) % of total energy intake (%E). The mean SFA intake was 13·8 (sd1·2) %E, with 99·8 % of the population exceeding the recommendations. SFA was mainly delivered by meat and cake, pies and biscuits. In most adolescents, the PUFA intake was too low, and 35·5 % of the population did not achieve the minimum recommended intake for α-linolenic acid (ALA). The main determinants of FA intake in the present study population were age and sex, as well as physical activity in the male subgroup. No contributions of body composition, socio-economic status or sexual maturation to the variance in FA intake were observed. In conclusion, the most important public health concerns regarding FA intake in this adolescent population were the low intake of ALA and the high intake of SFA, mainly seen in the younger-aged boys. In this group the major contributor to SFA was meat.</jats:p