Louise Bergmann Sørensen

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.

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.

The effects of Nordic school meals on concentration and school performance in 8- to 11-year-old children in the OPUS School Meal Study: a cluster-randomised, controlled, cross-over trial.

It is widely assumed that nutrition can improve school performance in children; however, evidence remains limited and inconclusive. In the present study, we investigated whether serving healthy school meals influenced concentration and school performance of 8- to 11-year-old Danish children. The OPUS (Optimal well-being, development and health for Danish children through a healthy New Nordic Diet) School Meal Study was a cluster-randomised, controlled, cross-over trial comparing a healthy school meal programme with the usual packed lunch from home (control) each for 3 months (NCT 01457794). The d2 test of attention, the Learning Rating Scale (LRS) and standard tests on reading and mathematics proficiency were administered at baseline and at the end of each study period. Intervention effects were evaluated using hierarchical mixed models. The school meal intervention did not influence concentration performance (CP; primary outcome, n 693) or processing speed; however, the decrease in error percentage was 0·18 points smaller (P<0·001) in the intervention period than in the control period (medians: baseline 2·03%; intervention 1·46%; control 1·37%). In contrast, the intervention increased reading speed (0·7 sentence, P=0·009) and the number of correct sentences (1·8 sentences, P<0·001), which corresponded to 11 and 25%, respectively, of the effect of one school year. The percentage of correct sentences also improved (P<0·001), indicating that the number correct improved relatively more than reading speed. There was no effect on overall math performance or outcomes from the LRS. In conclusion, school meals did not affect CP, but improved reading performance, which is a complex cognitive activity that involves inference, and increased errors related to impulsivity and inattention. These findings are worth examining in future trials.

Accuracy of self-reported intake of signature foods in a school meal intervention study: comparison between control and intervention period

Bias in self-reported dietary intake is important when evaluating the effect of dietary interventions, particularly for intervention foods. However, few have investigated this in children, and none have investigated the reporting accuracy of fish intake in children using biomarkers. In a Danish school meal study, 8- to 11-year-old children (n 834) were served the New Nordic Diet (NND) for lunch. The present study examined the accuracy of self-reported intake of signature foods (berries, cabbage, root vegetables, legumes, herbs, potatoes, wild plants, mushrooms, nuts and fish) characterising the NND. Children, assisted by parents, self-reported their diet in a Web-based Dietary Assessment Software for Children during the intervention and control (packed lunch) periods. The reported fish intake by children was compared with their ranking according to fasting whole-blood EPA and DHA concentration and weight percentage using the Spearman correlations and cross-classification. Direct observation of school lunch intake (n 193) was used to score the accuracy of food-reporting as matches, intrusions, omissions and faults. The reporting of all lunch foods had higher percentage of matches compared with the reporting of signature foods in both periods, and the accuracy was higher during the control period compared with the intervention period. Both Spearmans rank correlations and linear mixed models demonstrated positive associations between EPA+DHA and reported fish intake. The direct observations showed that both reported and real intake of signature foods did increase during the intervention period. In conclusion, the self-reported data represented a true increase in the intake of signature foods and can be used to examine dietary intervention effects.

Vitamin D status and its determinants during autumn in children at northern latitudes: a cross-sectional analysis from the OPUS School Meal Study

Sufficient summer/autumn vitamin D status appears important to mitigate winter nadirs at northern latitudes. We conducted a cross-sectional study to evaluate autumn vitamin D status and its determinants in 782 Danish 8–11-year-old children (55°N) using baseline data from the Optimal well-being, development and health for Danish children through a healthy New Nordic Diet (OPUS) School Meal Study, a large randomised controlled trial. Blood samples and demographic and behavioural data, including 7-d dietary recordings, objectively measured physical activity, and time spent outdoors during school hours, were collected during September–November. Mean serum 25-hydroxyvitamin D (25(OH)D) was 60·8 (SD 18·7) nmol/l. Serum 25(OH)D levels ≤50 nmol/l were found in 28·4% of the children and 2·4% had concentrations <25 nmol/l. Upon multivariate adjustment, increasing age (per year) (β −2·9; 95 % CI −5·1, −0·7 nmol/l), female sex (β −3·3; 95 % CI −5·9, −0·7 nmol/l), sampling in October (β −5·2; 95 % CI −10·1, −0·4 nmol/l) and November (β −13·3; 95% CI −17·7, −9·1), and non-white ethnicity (β −5·7; 95% CI −11·1, −0·3 nmol/l) were negatively associated with 25(OH)D (all P<0·05). Likewise, immigrant/descendant background was negatively associated with 25(OH)D, particularly in females (β −16·3; 95 % CI −21·9, −10·7) (P< 0·001) (Pinteraction= 0·003). Moderate-to-vigorous physical activity (MVPA) (min/d) (β 0·06; 95 % CI 0·01, 0·12), outdoor walking during school hours (min/week) (β 0·4; 95% CI 0·1, 0·6) and intake of vitamin D-containing supplements ≥3 d/week (β 8·7; 95 % CI 6·4, 11·0) were positively associated with 25(OH)D (all P<0·05). The high proportion of children with vitamin D status below the recommended sufficiency level of 50 nmol/l raises concern as levels expectedly drop further during winter months. Frequent intake of vitamin D supplements was strongly associated with status. MVPA and outdoor activity during school hours should be investigated further in interventions to improve autumn vitamin D status in children at northern latitudes.Sufficient summer/autumn vitamin D status appears important to mitigate winter nadirs at northern latitudes. We conducted a cross-sectional study to evaluate autumn vitamin D status and its determinants in 782 Danish 8-11-year-old children (55°N) using baseline data from the Optimal well-being, development and health for Danish children through a healthy New Nordic Diet (OPUS) School Meal Study, a large randomised controlled trial. Blood samples and demographic and behavioural data, including 7-d dietary recordings, objectively measured physical activity, and time spent outdoors during school hours, were collected during September-November. Mean serum 25-hydroxyvitamin D (25(OH)D) was 60·8 (sd 18·7) nmol/l. Serum 25(OH)D levels ≤50 nmol/l were found in 28·4 % of the children and 2·4 % had concentrations <25 nmol/l. Upon multivariate adjustment, increasing age (per year) (β -2·9; 95 % CI -5·1, -0·7 nmol/l), female sex (β -3·3; 95 % CI -5·9, -0·7 nmol/l), sampling in October (β -5·2; 95 % CI -10·1, -0·4 nmol/l) and November (β -13·3; 95 % CI -17·7, -9·1), and non-white ethnicity (β -5·7; 95 % CI -11·1, -0·3 nmol/l) were negatively associated with 25(OH)D (all P<0·05). Likewise, immigrant/descendant background was negatively associated with 25(OH)D, particularly in females (β -16·3; 95 % CI -21·9, -10·7) (P<0·001) (P interaction=0·003). Moderate-to-vigorous physical activity (MVPA) (min/d) (β 0·06; 95 % CI 0·01, 0·12), outdoor walking during school hours (min/week) (β 0·4; 95 % CI 0·1, 0·6) and intake of vitamin D-containing supplements ≥3 d/week (β 8·7; 95 % CI 6·4, 11·0) were positively associated with 25(OH)D (all P<0·05). The high proportion of children with vitamin D status below the recommended sufficiency level of 50 nmol/l raises concern as levels expectedly drop further during winter months. Frequent intake of vitamin D supplements was strongly associated with status. MVPA and outdoor activity during school hours should be investigated further in interventions to improve autumn vitamin D status in children at northern latitudes.

The Role of Leptin and Other Hormones Related to Bone Metabolism and Appetite Regulation as Determinants of Gain in Body Fat and Fat-Free Mass in 8–11-Year-Old Children

BACKGROUND Regulation of body composition during childhood is complex. Numerous hormones are potentially involved. Leptin has been proposed to restrain weight gain, but results are inconsistent. OBJECTIVE We examined whether baseline fasting levels of ghrelin, adiponectin, leptin, insulin, IGF-I, osteocalcin, and intact parathyroid hormone (iPTH) were associated with body composition cross sectionally and longitudinally in 633 8-11-year-olds. DESIGN Data on hormones and body composition by dual-energy x-ray absorptiometry from the OPUS School Meal Study were used. We looked at baseline hormones as predictors of baseline fat mass index (FMI) or fat-free mass index (FFMI), and also subsequent changes (3 and 6 months) in FMI or FFMI using models with hormones individually or combined. RESULTS Cross-sectionally, baseline leptin was positively associated with FMI in girls (0.211 kg/m(2) pr. μg/mL; 97.5% confidence interval [CI],0.186-0.236; P < .001) and boys (0.231 kg/m(2) pr. μg/mL; 97.5% CI, 0.200-0.261; P < .001). IGF-I in both sexes and iPTH in boys were positively associated with FMI. An inverse association between adiponectin and FFMI in boys and a positive association between IGF-I and FFMI were found in girls. In longitudinal models, baseline leptin was inversely associated with subsequent changes in FMI (-0.018 kg/m(2) pr. μg/mL; 97.5% CI, -0.034 - -0.002; P = .028) and FFMI (-0.014 kg/m(2) pr. μg/mL; 97.5% CI, -0.024 - -0.003; P = .006) in girls. CONCLUSIONS Cross-sectional findings support that leptin is produced in proportion to body fat mass, but the longitudinal observations support that leptin inhibits gains in FMI and FFMI in girls, a finding that may reflect preserved leptin sensitivity in this predominantly normal weight population.

Normal weight children have higher cognitive performance – Independent of physical activity, sleep, and diet

BACKGROUND/OBJECTIVES Aside from the health consequences, observational studies indicate that being overweight may also negatively affect cognitive function. However, existing evidence has to a large extent not controlled for the possible confounding effect of having different lifestyles. Therefore, the objective was to examine the independent associations between weight status and lifestyle indicators with cognitive performance in 8-11year old Danish children. SUBJECTS/METHODS The analyses included 828 children (measured in 2011-2012) each having one to three measurement occasions separated by approximately 100days. Dietary intake, physical activity, sedentary time, and sleep duration were measured using dietary records and accelerometers. The Childrens Sleep Habits Questionnaire was used to access sleep problems and the Andersen test was carried out to estimate cardio-respiratory fitness (CRF). Weight status (underweight, normal weight, and overweight/obese) was defined according to body mass index and cognitive performance was assessed using the d2-test of attention, a reading test, and a math test. A linear mixed model including a number of fixed and random effects was used to test associations between lifestyle indicators as well as BMI category and cognitive performance. RESULTS After adjustment for demographics, socioeconomics, and multiple lifestyle indicators, normal weight children had higher cognitive test scores than overweight/obese and underweight children of up to 89% and 48% of expected learning within one school year (P<0.05). Daily breakfast consumption, fewer sleep problems, higher CRF, less total physical activity, more sedentary time, and less light physical activity were associated with higher cognitive performance independently of each other in at least one of the three cognitive tests (P<0.05). CONCLUSIONS Normal weight children had higher cognitive performance compared to overweight/obese as well as underweight children, independent of multiple lifestyle indicators.

Seasonal variations in growth and body composition of 8-11-y-old Danish children

Background:Earlier studies on seasonality in growth reported the largest height gains during spring and largest body weight gains during autumn. We examined seasonality in height, body weight, BMI, fat mass index (FMI), and fat-free mass index (FFMI) among contemporary Danish 8–11-y olds.Methods:A total of 760 children from the OPUS School Meal Study provided >2,200 measurements on height, body weight, and composition between September and June. Average velocities were calculated using change-score analyses based on 3-mo intervals. As a complementary analysis, point velocities derived from estimated growth curves were fitted using semiparametric regression that included covariate adjustment and allowed flexible modeling of the time trend.Results:Average velocities showed the following trends: height was higher than the average (6.10 cm/y) in January–April. Body weight was below the average (4.02 kg/y) in August–January and above in January–May; BMI (average: 0.49 kg/ m2/y) and FFMI (average: 0.17 kg/m2/y) showed similar trends. In contrast, FMI was above the average (0.38 kg/m2/y) in November–March. Similar trends were seen for point velocities.Conclusion:Our findings suggest seasonality in growth and body composition of Danish children. We recovered the well-known height velocity peak during spring time, but unlike earlier studies, we found coincident peaks in body weight, BMI, and FFMI velocities.

Mendelian randomization shows sex-specific associations between long-chain PUFA–related genotypes and cognitive performance in Danish schoolchildren

Background: Dietary and endogenously formed long-chain polyunsaturated fatty acids (LCPUFAs) are hypothesized to improve cognitive development, but results are inconclusive, with suggestions of sex specificity. One study suggested that single-nucleotide polymorphisms (SNPs) rs1535 and rs174448 in the fatty acid desaturase (FADS) gene cluster have opposite effects on erythrocyte LCPUFAs at 9 mo.Objective: To explore whether SNPs in FADS and elongase (ELOVL) genes were associated with school performance in a sex-specific manner, we performed a Mendelian randomization study using data from the Optimal well-being, development and health for Danish children through a healthy New Nordic Diet (OPUS) School Meal Study with 765 Danish schoolchildren 8-11 y old.Design: Associations between selected FADS1/2 SNPs (rs1535, rs174448, and rs174468) and ELOVL5 rs2397142, whole-blood fatty acid composition, and performance in the d2 Test of Attention and a reading test were analyzed in multiple regression models including all SNPs, SNP-sex interactions, and covariates related to testing conditions.Results:FADS, rs1535 minor allele carriage associated with lower whole-blood arachidonic acid (P ≤ 0.002), and minor alleles of rs174448 tended to associate with lower docosahexaenoic acid (DHA) (P = 0.052). We identified sex interactions in 50% of the SNP performance sets. Sex-dependent associations were observed for rs174448 and rs1535 on the d2 Test of Attention outcomes (P < 0.03) and for the associations between reading scores and rs174448 and rs2397142 (P < 0.01). All of the sex-specific analyses showed associations in opposite directions in girls and boys. The minor allele carriage of rs174448 was associated with lower d2 Test of Attention performance (P < 0.02) and reading scores (P < 0.001) in boys but with better reading scores in girls (P ≤ 0.002). The associations were consistently the opposite for rs1535 minor allele carriage (P < 0.05). Associations with rs2397142 also appeared to be opposite of those of rs174448, but only for reading and not significant after adjustment for parental educational level and whole-blood DHA.Conclusions: This study showed associations between rs1535 minor allele homozygosity and rs174448 major allele carriage and improved performance in 8- to 11-y-old boys but not in girls, thereby counteracting existing sex differences. This may be a consequence of increased endogenous DHA synthesis in infancy but not at school-age. This trial was registered at clinicaltrials.gov as NCT01457794.

What do Danish children eat, and does the diet meet the recommendations? Baseline data from the OPUS School Meal Study

A childs diet is an important determinant for later health, growth and development. In Denmark, most children in primary school bring their own packed lunch from home and attend an after-school care institution. The aim of the present study was to evaluate the food, energy and nutrient intake of Danish school children in relation to dietary guidelines and nutrient recommendations, and to assess the food intake during and outside school hours. In total, 834 children from nine public schools located in the eastern part of Denmark were included in this cross-sectional study and 798 children (95·7 %) completed the dietary assessment sufficiently (August–November 2011). The whole diet was recorded during seven consecutive days using the Web-based Dietary Assessment Software for Children (WebDASC). Compared with the food-based dietary guidelines and nutrient recommendations, 85 % of the children consumed excess amounts of red meat, 89 % consumed too much saturated fat, and 56 % consumed too much added sugar. Additionally 35 or 91 % of the children (depending on age group) consumed insufficient amounts of fruits and vegetables, 85 % consumed insufficient amounts of fish, 86 % consumed insufficient amounts of dietary fibre, 60 or 84 % had an insufficient Fe intake (depending on age group), and 96 % had an insufficient vitamin D intake. The study also showed that there is a higher intake of fruits and bread during school hours than outside school hours; this is not the case with, for example, fish and vegetables, and future studies should investigate strategies to increase fish and vegetable intake during school hours.