Mads F. Hjorth

Fatness predicts decreased physical activity and increased sedentary time, but not vice versa: support from a longitudinal study in 8- to 11-year-old children

Objective:To examine independent and combined cross-sectional associations between movement behaviors (physical activity (PA), sedentary time, sleep duration, screen time and sleep disturbance) and fat mass index (FMI), as well as to examine longitudinal associations between movement behaviors and FMI.Methods:Cross-sectional and longitudinal analyses were done using data from the OPUS school meal study on 785 children (52% boys, 13.4% overweight, ages 8–11 years). Total PA, moderate-to-vigorous PA (MVPA), sedentary time and sleep duration (7 days and 8 nights) were assessed by an accelerometer and FMI was determined by dual-energy X-ray absorptiometry (DXA) on three occasions over 200 days. Demographic characteristics, screen time and sleep disturbance (Children’s Sleep Habits Questionnaire) were also obtained.Results:Total PA, MVPA and sleep duration were negatively associated with FMI, while sedentary time and sleep disturbances were positively associated with FMI (P⩽0.01). However, only total PA, MVPA and sleep duration were independently associated with FMI after adjustment for multiple covariates (P<0.001). Nevertheless, combined associations revealed synergistic effects among the different movement behaviors. Changes over time in MVPA were negatively associated with changes in FMI (P<0.001). However, none of the movement behaviors at baseline predicted changes in FMI (P>0.05), but higher FMI at baseline predicted a decrease in total PA and MVPA, and an increase in sedentary time (P⩽0.001), even in normal-weight children (P⩽0.03).Conclusion:Total PA, MVPA and sleep duration were independently associated with FMI, and combined associations of movement behaviors showed a synergistic effect with FMI. In the longitudinal study design, a high FMI at baseline was associated with lower PA and higher sedentary time after 200 days but not vice versa, even in normal-weight children. Our results suggest that adiposity is a better predictor of PA and sedentary behavior changes than the other way around.

Short sleep duration and large variability in sleep duration are independently associated with dietary risk factors for obesity in Danish school children

Background:Lack of sleep and increased consumption of energy-dense foods and sugar-sweetened beverages (SSBs) have all been suggested as factors contributing to the increased prevalence of overweight and obesity.Objective:To evaluate whether objectively measured sleep duration (average and day-to-day variability) as well as parent-reported sleep problems are independently associated with proposed dietary risk factors for overweight and obesity in 8–11-year-old children.Design:In this cross-sectional study, data on sleep duration and day-to-day variability in sleep duration were measured in 676 Danish, apparently healthy children by an objective measure (actigraphy) for 8 nights, and the Children’s Sleep Habits Questionnaire (CSHQ) was filled out by the parents. Diet was recorded using a web-based food record for 7 consecutive days. Fasting blood samples were obtained for measurements of plasma leptin and ghrelin levels.Results:Sleep duration (h per night) was negatively associated with energy density (ED) of the diet (β=−0.32 kJ g−1), added sugar (β=−1.50 E%) and SSBs (β=−1.07 E%) (all P⩽0.003). Furthermore, variability in sleep duration (10-min per night) was positively associated with SSBs (β=0.20 E%, P=0.03), independent of sleep duration, and CSHQ score was positively associated with ED (β=0.16 kJ g−1, P=0.04). All of these associations were independent of potential confounders (age, sex, pubertal status, height, weight, screen time, moderate-to-vigorous physical activity and parental education and ethnicity).Conclusion:Our study suggests that short sleep duration, high sleep duration variability and experiencing sleep problems are all associated with a poor, obesity-promoting diet in children.

Design of the OPUS School Meal Study: a randomised controlled trial assessing the impact of serving school meals based on the New Nordic Diet.

Introduction: Danish children consume too much sugar and not enough whole grain, fish, fruit, and vegetables. The Nordic region is rich in such foods with a strong health-promoting potential. We lack randomised controlled trials that investigate the developmental and health impact of serving school meals based on Nordic foods. Aim: This paper describes the rationale, design, study population, and potential implications of the Optimal well-being, development and health for Danish children through a healthy New Nordic Diet (OPUS) School Meal Study. Methods: In a cluster-randomised cross-over design, 1021 children from 3rd and 4th grades (8–11 years old) at nine Danish municipal schools were invited to participate. Classes were assigned to two 3-month periods with free school meals based on the New Nordic Diet (NND) or their usual packed lunch (control). Dietary intake, nutrient status, physical activity, cardiorespiratory fitness, sleep, growth, body composition, early metabolic and cardiovascular risk markers, illness, absence from school, wellbeing, cognitive function, social and cultural features, food acceptance, waste, and cost were assessed. Results: In total, 834 children (82% of those invited) participated. Although their parents were slightly better educated than the background population, children from various socioeconomic backgrounds were included. The proportion of overweight and obese children (14%) resembled that of earlier examinations of Danish school children. Drop out was 8.3%. Conclusions: A high inclusion rate and low drop out rate was achieved. This study will be the first to determine whether school meals based on the NND improve children’s diet, health, growth, cognitive performance, and early disease risk markers.

Low physical activity level and short sleep duration are associated with an increased cardio-metabolic risk profile: a longitudinal study in 8-11 year old Danish children.

Background As cardio-metabolic risk tracks from childhood to adulthood, a better understanding of the relationship between movement behaviors (physical activity, sedentary behavior and sleep) and cardio-metabolic risk in childhood may aid in preventing metabolic syndrome (MetS) in adulthood. Objective To examine independent and combined cross-sectional and longitudinal associations between movement behaviors and the MetS score in 8-11 year old Danish children. Design Physical activity, sedentary time and sleep duration (seven days and eight nights) were assessed by accelerometer and fat mass index (fat mass/height2) was assessed using Dual-energy X-ray absorptiometry. The MetS-score was based on z-scores of waist circumference, mean arterial blood pressure, homeostatic model assessment of insulin resistance, triglycerides and high density lipoprotein cholesterol. All measurements were taken at three time points separated by 100 days. Average of the three measurements was used as habitual behavior in the cross-sectional analysis and changes from first to third measurement was used in the longitudinal analysis. Results 723 children were included. In the cross-sectional analysis, physical activity was negatively associated with the MetS-score (P<0.03). In the longitudinal analysis, low physical activity and high sedentary time were associated with an increased MetS-score (all P<0.005); however, after mutual adjustments for movement behaviors, physical activity and sleep duration, but not sedentary time, were associated with the MetS-score (all P<0.03). Further adjusting for fat mass index while removing waist circumference from the MetS-score rendered the associations no longer statistically significant (all P>0.17). Children in the most favorable tertiles of changes in moderate-to-vigorous physical activity, sleep duration and sedentary time during the 200-day follow-up period had an improved MetS-score relative to children in the opposite tertiles (P = 0.005). Conclusion The present findings indicate that physical activity, sedentary time and sleep duration should all be targeted to improve cardio-metabolic risk markers in childhood; this is possibly mediated by adiposity.

An excess of chromosome 1 breakpoints in male infertility.

In a search for potential infertility loci, which might be revealed by clustering of chromosomal breakpoints, we compiled 464 infertile males with a balanced rearrangement from Mendelian Cytogenetics Network database (MCNdb) and compared their karyotypes with those of a Danish nation-wide cohort. We excluded Robertsonian translocations, rearrangements involving sex chromosomes and common variants. We identified 10 autosomal bands, five of which were on chromosome 1, with a large excess of breakpoints in the infertility group. Some of these could potentially harbour a male-specific infertility locus. However, a general excess of breakpoints almost everywhere on chromosome 1 was observed among the infertile males: 26.5 versus 14.5% in the cohort. This excess was observed both for translocation and inversion carriers, especially pericentric inversions, both for published and unpublished cases, and was significantly associated with azoospermia. The largest number of breakpoints was reported in 1q21; FISH mapping of four of these breakpoints revealed that they did not involve the same region at the molecular level. We suggest that chromosome 1 harbours a critical domain whose integrity is essential for male fertility.

No relation between sleep duration and adiposity indicators in 9–36 months old children: the SKOT cohort

Epidemiological studies in adults and children have repeatedly reported an association between short sleep duration and the risk of obesity. Studies using both objective measurements of sleep and dual‐energy X‐ray absorptiometry in children aged three are, however, lacking.

Provision of healthy school meals does not affect the metabolic syndrome score in 8-11-year-old children, but reduces cardiometabolic risk markers despite increasing waist circumference.

An increasing number of children are exhibiting features of the metabolic syndrome (MetS) including abdominal fatness, hypertension, adverse lipid profile and insulin resistance. Healthy eating practices during school hours may improve the cardiometabolic profile, but there is a lack of evidence. In the present study, the effect of provision of school meals rich in fish, vegetables and fibre on a MetS score (primary outcome) and on individual cardiometabolic markers and body composition (secondary outcomes) was investigated in 834 Danish school children. The study was carried out as a cluster-randomised, controlled, non-blinded, cross-over trial at nine schools. Children aged 8-11 years received freshly prepared school lunch and snacks or usual packed lunch from home (control) each for 3 months. Dietary intake, physical activity, cardiometabolic markers and body composition were measured at baseline and after each dietary period. The school meals did not affect the MetS score (P= 1.00). However, it was found that mean arterial pressure was reduced by 0.4 (95% CI 0.0, 0.8) mmHg (P= 0.04), fasting total cholesterol concentrations by 0.05 (95% CI 0.02, 0.08) mmol/l (P= 0.001), HDL-cholesterol concentrations by 0.02 (95% CI 0.00, 0.03) mmol/l, TAG concentrations by 0.02 (95% CI 0.00, 0.04) mmol/l (both P< 0.05), and homeostasis model of assessment-insulin resistance by 0.10 (95% CI 0.04, 0.16) points (P= 0.001) compared with the control diet in the intention-to-treat analyses. Waist circumference increased 0.5 (95% CI 0.3, 0.7) cm (P< 0.001), but BMI z-score remained unaffected. Complete-case analyses and analyses adjusted for household educational level, pubertal status and physical activity confirmed the results. In conclusion, the school meals did not affect the MetS score in 8-11-year-olds, as small improvements in blood pressure, TAG concentrations and insulin resistance were counterbalanced by slight undesired effects on waist circumference and HDL-cholesterol concentrations.

Sleep and cardiometabolic risk in children and adolescents

The evidence for a link between sleep and cardiometabolic risk factors in children and adolescents is accumulating; however, the literature has not yet been reviewed. Seventy-five studies investigating associations between sleep variables and measures of abdominal adiposity, glucose homeostasis, blood lipids, blood pressure (BP), and inflammatory markers were included in the present review. The current evidence indicates that inadequate sleep may play a role in cardiometabolic risk at a later age for children and adolescents. Most compelling is the evidence for an association between inadequate sleep and abdominal adiposity, decreased insulin sensitivity as well as high BP, whereas the evidence for potential links between sleep and blood lipids as well as inflammatory markers is less convincing. It should, however, be noted that the majority of studies linking sleep with cardiometabolic outcomes are cross-sectional in nature, and sleep is often assessed using parent or self-report. We suggest that future studies should investigate longitudinal associations between sleep and cardiometabolic risk factors with the use of objective sleep measurements conducted for several days, including weekdays and weekend days, at multiple time points over time. Meanwhile, based on the available evidence, we recommend that children and adolescents get adequate amounts of good sleep in a regular pattern.

Comparison of estimated energy intake using Web-based Dietary Assessment Software with accelerometer-determined energy expenditure in children

Background The OPUS (Optimal well-being, development and health for Danish children through a healthy New Nordic Diet) project carried out a school meal study to assess the impact of a New Nordic Diet (NND). The random controlled trial involved 834 children aged 8–11 in nine local authority schools in Denmark. Dietary assessment was carried out using a program known as WebDASC (Web-based Dietary Assessment Software for Children) to collect data from the children. Objective To compare the energy intake (EI) of schoolchildren aged 8–11 estimated using the WebDASC system against the total energy expenditure (TEE) as derived from accelerometers worn by the children during the same period. A second objective was to evaluate the WebDASCs usability. Design Eighty-one schoolchildren took part in what was the pilot study for the OPUS project, and they recorded their total diet using WebDASC and wore an accelerometer for two periods of seven consecutive days: at baseline, when they ate their usual packed lunches and at intervention when they were served the NND. EI was estimated using WebDASC, and TEE was calculated from accelerometer-derived activity energy expenditure, basal metabolic rate, and diet-induced thermogenesis. WebDASCs usability was assessed using a questionnaire. Parents could help their children record their diet and answer the questionnaire. Results Evaluated against TEE as derived from the accelerometers worn at the same time, the WebDASC performed just as well as other traditional methods of collecting dietary data and proved both effective and acceptable with children aged 8–11, even with perhaps less familiar foods of the NND. Conclusions WebDASC is a useful method that provided a reasonably accurate measure of EI at group level when compared to TEE derived from accelerometer-determined physical activity in children. WebDASC will benefit future research in this area.

Pretreatment fasting plasma glucose and insulin modify dietary weight loss success: results from 3 randomized clinical trials

Background: Which diet is optimal for weight loss and maintenance remains controversial and implies that no diet fits all patients.Objective: We studied concentrations of fasting plasma glucose (FPG) and fasting insulin (FI) as prognostic markers for successful weight loss and maintenance through diets with different glycemic loads or different fiber and whole-grain content, assessed in 3 randomized trials of overweight participants.Design: After an 8-wk weight loss, participants in the DiOGenes (Diet, Obesity, and Genes) trial consumed ad libitum for 26 wk a diet with either a high or a low glycemic load. Participants in the Optimal well-being, development and health for Danish children through a healthy New Nordic Diet (OPUS) Supermarket intervention (SHOPUS) trial consumed ad libitum for 26 wk the New Nordic Diet, which is high in fiber and whole grains, or a control diet. Participants in the NUGENOB (Nutrient-Gene Interactions in Human Obesity) trial consumed a hypocaloric low-fat and high-carbohydrate or a high-fat and low-carbohydrate diet for 10 wk. On the basis of FPG before treatment, participants were categorized as normoglycemic (FPG <5.6 mmol/L), prediabetic (FPG 5.6-6.9 mmol/L), or diabetic (FPG ≥7.0 mmol/L). Modifications of the dietary effects of FPG and FI before treatment were examined with linear mixed models.Results: In the DiOGenes trial, prediabetic individuals regained a mean of 5.83 kg (95% CI: 3.34, 8.32 kg; P < 0.001) more on the high- than on the low-glycemic load diet, whereas normoglycemic individuals regained a mean of 1.44 kg (95% CI: 0.48, 2.41 kg; P = 0.003) more [mean group difference: 4.39 kg (95% CI: 1.76, 7.02 kg); P = 0.001]. In SHOPUS, prediabetic individuals lost a mean of 6.04 kg (95% CI: 4.05, 8.02 kg; P < 0.001) more on the New Nordic Diet than on the control diet, whereas normoglycemic individuals lost a mean of 2.20 kg (95% CI: 1.21, 3.18 kg; P < 0.001) more [mean group difference: 3.84 kg (95% CI: 1.62, 6.06 kg); P = 0.001]. In NUGENOB, diabetic individuals lost a mean of 2.04 kg (95% CI: -0.20, 4.28 kg; P = 0.07) more on the high-fat and low-carbohydrate diet than on the low-fat and high-carbohydrate diet, whereas normoglycemic individuals lost a mean of 0.43 kg (95% CI: 0.03, 0.83 kg; P = 0.03) more on the low-fat and high-carbohydrate diet [mean group difference: 2.47 kg (95% CI: 0.20, 4.75 kg); P = 0.03]. The addition of FI strengthened these associations.Conclusion: Elevated FPG before treatment indicates success with dietary weight loss and maintenance among overweight patients consuming diets with a low glycemic load or with large amounts of fiber and whole grains. These trials were registered at clinicaltrials.gov as NCT00390637 (DiOGenes) and NCT01195610 (SHOPUS), and at ISRNCT.com as ISRCTN25867281 (NUGENOB).