Vitamin D status of 3-year-old children in Denmark: determinants and associations with bone mineralisation and blood lipids.

PURPOSE: Low vitamin D status is a global problem and has been associated with reduced skeletal and cardiometabolic health. However, evidence in young children is lacking. We, therefore, aimed to characterise vitamin D status in toddlers, identify its determinants, and explore if vitamin D status was associated with bone mineralisation and lipid profile. METHODS: We used cross-sectional data from 3-year-old children (n = 323) living in Denmark (latitude: 55°N). Bone mineralisation (n = 108) was measured by DXA. Blood samples were analysed for serum 25-hydroxyvitamin D (s-25(OH)D) by LC-MS/MS, triacylglycerol, and total, low- and high density lipoprotein cholesterol. RESULTS: Mean ± SD s-25(OH)D was 69 ± 23 nmol/L, but varied with season. During winter, 38% had inadequate s-25(OH)D (< 50 nmol), whereof 15% had deficiency (< 30 nmol/L); these numbers were only 7 and 1% during summer. In terms of status determinants, supplement use (66% were users) was associated with s-25(OH)D (P < 0.001), whereas dietary vitamin D intake (median [25-75th percentile] of 1.3 [0.9-1.9] µg/d), sex, parental education, BMI, and physical activity were not. There were no associations between s-25(OH)D and blood lipids or bone measurements, using either unadjusted or adjusted regression models. CONCLUSION: More than 1/3 of Danish toddlers had inadequate vitamin D intake during winter, but acceptable mean vitamin D status. In addition to season, supplement use was the main determinant of vitamin D status, which was, however, not associated with bone mineralisation or lipid profile. The results support recommendations of vitamin D supplements during winter at northern latitudes, but potential health effects need further investigation.

Vitamin D supplementation and increased dairy protein intake do not affect muscle strength or physical function in healthy 6-8-year-old children: the D-pro randomized trial.

PURPOSE: To investigate separate and combined effects of vitamin D supplementation during the extended winter and increased dairy protein intake on muscle strength and physical function in children, and furthermore to explore potential sex differences. METHODS: In a 2 × 2-factorial, randomized winter trial, 183 healthy, 6-8-year-old children received blinded tablets with 20 µg/day vitamin D3 or placebo, and substituted 260 g/day dairy with yogurts with high (HP, 10 g protein/100 g) or normal protein content (NP, 3.5 g protein/100 g) for 24 weeks during winter at 55° N. We measured maximal isometric handgrip and leg press strength, and physical function by jump tests and a 30 s sit-to-stand test. Physical activity was measured by 7-day accelerometry. RESULTS: Baseline (mean ± SD) serum 25-hydroxyvitamin D was 80.8 ± 17.2 nmol/L, which increased to 88.7 ± 17.6 nmol/L with vitamin D supplementation and decreased to 48.4 ± 19.2 nmol/L with placebo. Baseline protein intake was 15.5 ± 2.4 E%, which increased to 18.4 ± 3.4 E% with HP and was unchanged with NP. We found no separate or combined effects of vitamin D supplementation and/or increased dairy protein intake on muscle strength or physical function (all P > 0.20). There was an interaction on the sit-to-stand test (Pvitamin×yogurt = 0.02), which however disappeared after adjusting for physical activity (P = 0.16). Further, vitamin D supplementation increased leg press strength relatively more in girls compared to boys (mean [95% CI] 158 [17, 299] N; Pvitamin×sex = 0.047). CONCLUSION: Overall, vitamin D and dairy protein supplementation during the extended winter did not affect muscle strength or physical function in healthy children. Potential sex differences of vitamin D supplementation should be investigated further. REGISTERED AT CLINICALTRIALS.GOV: NCT0395673.

Wholegrain intake, growth and metabolic markers in Danish infants and toddlers: a longitudinal study.

PURPOSE: Wholegrain intake is linked to lower risk of lifestyle diseases, but little is known about its role in growth and metabolic health during the first years of life. We characterized wholegrain and dietary fibre intake in 439 Danish children at 9 and 36 months of age and explored associations with height z-scores (HAZ), body mass index z-scores (BMIZ) and metabolic markers. METHODS: We used pooled data from two infant cohorts and estimated intakes of total wholegrain, dietary fibre and wholegrain subtypes from 7-day dietary records. Associations with HAZ, BMIZ and non-fasting plasma low-density (LDLC) and high-density-lipoprotein cholesterol, triacylglycerol, insulin and glucose were analysed in mixed models, adjusted for potential confounders. RESULTS: Median (25th, 75th percentile) wholegrain intake was 7.5 (4.9, 10.5) and 6.5 (4.6, 9.0) g/MJ at 9 and 36 months. Neither wholegrain nor dietary fibre intake were associated with HAZ (P ≥ 0.09). At 36 months, wholegrain intake was inversely associated with LDLC (P = 0.05) and directly with glucose (P < 0.001). In secondary analyses, wholegrain rye was inversely associated with glucose at 9 months and insulin at 36 months (both P ≤ 0.03). Oat and wheat wholegrain were directly associated with glucose (both P ≤ 0.01) and wheat with BMIZ (P = 0.02) at 36 months. CONCLUSION: Danish infants and toddlers have high intakes of wholegrain and dietary fibre, with no indication of compromised growth. In line with studies in adults, wholegrain intake was inversely associated with LDLC. The observed direct association between wholegrain intake and plasma glucose and associations with wholegrain subtypes should be investigated further.

Does polymorphisms in PPAR and APOE genes modify associations between fatty acid desaturase (FADS), n-3 long-chain PUFA and cardiometabolic markers in 8-11-year-old Danish children?

n-3 Long-chain PUFA (LCPUFA) can improve cardiometabolic blood markers, but studies in children are limited. SNP in the FADS genes, which encode fatty acid desaturases, influence endogenous LCPUFA production. Moreover, SNP in genes that encode PPAR and apoE may modulate the effects of n-3 LCPUFA. We explored whether FADS polymorphisms were associated with blood cholesterol and TAG, insulin and glucose and whether polymorphisms in PPAR and APOE modified associations between FADS or n-3 LCPUFA status and the cardiometabolic blood markers. We measured fasting cholesterol and TAG, insulin, glucose and n-3 LCPUFA in 757 Danish 8-11-year-old children and genotyped SNP in FADS (rs1535 and rs174448), PPARG2 (rs1801282), PPARA (rs1800206) and APOE (rs7412+rs429358). Carriage of two FADS rs174448 major alleles was associated with lower TAG (P = 0·027) and higher HDL-cholesterol (P = 0·047). Blood n-3 LCPUFA was inversely associated with TAG and insulin in PPARG2 minor allele carriers and positively with LDL-cholesterol in major allele homozygotes (Pn-3 LCPUFA × rs180182 < 0·01). Associations between n-3 LCPUFA and cardiometabolic markers were not modified by APOE genotype (Pn-3 LCPUFA × APOE > 0·11), but interaction between FADS rs1535 and APOE showed that rs1535 major allele homozygotes who also carried APOE2 had higher HDL-cholesterol than all other genotype combinations (Prs1535 × APOE = 0·019, pairwise-P < 0·05). This indicates that FADS genotypes, which increase endogenous LCPUFA production, may beneficially affect children's cardiometabolic profile in a partly APOE-dependent manner. Also, the degree to which children benefit from higher n-3 LCPUFA intake may depend on their PPARG2 genotype.

Exploring the effects of oily fish consumption on measures of acute and long-term stress in healthy 8-9-year-old children: the FiSK Junior randomised trial.

Long-chain n-3 PUFA (n-3 LCPUFA) are known to reduce blood pressure (BP), heart rate and vagal tone, but potential stress-mitigating effects of n-3 LCPUFA are not well investigated. We explored the effects of oily fish consumption on long-term stress and the stress response in schoolchildren. Healthy 8-9-year-old children were randomised to receive about 300 g/week of oily fish or poultry for 12 weeks (199 randomised, 197 completing). At baseline and endpoint, we measured erythrocyte n-3 LCPUFA, hair cortisol and the response to a 1-min cold pressor test (CPT) on saliva cortisol, BP and continuous electrocardiogram recordings. Post-intervention hair cortisol did not differ between the groups, but sex-specificity was indicated (Psex × group = 0·074, boys: -0·9 (95 % CI -2·9, 1·0) ng/g, girls: 0·7 (95 % CI -0·2, 1·6) ng/g). Children in the fish group tended to be less prone to terminate CPT prematurely (OR 0·20 (95 % CI 0·02, 1·04)). Mean heart beat interval during CPT was 18·2 (95 % CI 0·3, 36·6) ms longer and high frequency power increased (159 (95 % CI 29, 289) ms2) in the fish v. poultry group. The cardiac autonomic response in the 10 min following CPT was characterised by a sympathetic peak followed by a parasympathetic peak, which was most pronounced in the fish group. This exploratory study does not support a strong effect of oily fish consumption on stress but indicates that oily fish consumption may increase vagal cardiac tone during the physiological response to CPT. These results warrant further investigation.

Sleep and physical activity in healthy 8-9-year-old children are affected by oily fish consumption in the FiSK Junior randomized trial.

PURPOSE: Studies indicate that long-chain n-3 PUFA (n-3LCPUFA) affect sleep and physical activity (PA) in childhood. However, few studies used objective tools and none studies examined the effect of fish per se. We aimed to explore if fish consumption affected sleep and PA assessed by accelerometry in children, and if effects were modified by sex. METHODS: In a randomized 12-week trial, 199 healthy 8-9-year-old children received ~ 300 g/week of oily fish or poultry. Sleep and PA were pre-specified explorative outcomes examined by accelerometers that the children wore on their hip for 7 days at baseline and endpoint, while parents registered sleep. Compliance was verified by erythrocyte n-3LCPUFA. RESULTS: The children slept 9.4 ± 0.5 h/night but the sleep duration variability across the week was 6.0 (95%CI: 0.8, 11.1) min lower in the fish vs poultry group. Furthermore, children in the fish group exhibited increased spare time sedentary activity [9.4 (95%CI: 1.8, 16.9) min/day] at the expense of light PA [- 8.2 (95%CI: - 14.4, - 2.0) min/day]. These effects were supported by dose-dependency with n-3LCPUFA. Additionally, latency to sleep onset was reduced by 3.6 (95%CI: 1.0, 6.3) min on weekends and moderate-vigorous PA during school hours was 3.5 (95%CI: 0.1, 6.8) min longer in fish vs poultry. P values for sex interactions were all > 0.05 but the effects tended to be most pronounced on sleep in girls and PA in boys. CONCLUSION: Oily fish intake altered sleep and PA patterns among healthy schoolchildren, with some slight indications of sex differences. These findings warrant further investigation. CLINICAL TRIAL REGISTRY: At clinicaltrials.gov (NCT02809508) and a published protocol in Trials [Damsgaard et al. in Trials, 2016].

Vitamin D-related genes and cardiometabolic markers in healthy children: a Mendelian randomisation study.

Observational studies show associations between low serum 25-hydroxyvitamin D (25(OH)D) and cardiometabolic risk markers. This Mendelian randomisation study examined associations between cardiometabolic markers in children and SNP in genes related to vitamin D metabolism (DHCR7; group-specific complement (GC); cytochrome P450 subfamily IIR1 (CYP2R1); and CYP24A1) and action (CYP27B1 and VDR). In 699 healthy 8-11-year-old children, we genotyped eleven SNP. We generated a genetic risk score based on SNP associated with low 25(OH)D and investigated associations between this and blood pressure, plasma lipids and insulin. Furthermore, we examined whether SNP related to vitamin D actions modified associations between 25(OH)D and the cardiometabolic markers. All GC and CYP2R1 SNP influenced serum 25(OH)D. A risk score based on four of the six SNP was associated with 3·4 (95 % CI 2·6, 4·2) mmol/l lower 25(OH)D per risk allele (P < 0·001), but was not associated with the cardiometabolic markers. However, interactions were indicated for the three VDR SNP (Pinteraction < 0·081) on associations between 25(OH)D and TAG, systolic blood pressure and insulin, which all decreased with increasing 25(OH)D only in major allele homozygotes (ß -0·02 (95 % CI -0·04, -0·01) mmol/l; ß -0·5 (95 % CI -0·9, -0·1) mmHg; and ß -0·5 (95 % CI -1·4, 0·3) pmol/l, respectively). In conclusion, genetic variation affected 25(OH)D substantially, but the genetic score was not associated with cardiometabolic markers in children. However, VDR polymorphisms modified associations with vitamin D, which warrants further investigation of VDR's role in the relationship between vitamin D and cardiometabolic risk.

Is high oily fish intake achievable and how does it affect nutrient status in 8-9-year-old children?: the FiSK Junior trial.

PURPOSE: Most children do not meet dietary guidelines for fish intake. Fish is the main source of EPA (20:5n-3), DHA (22:6n-3) and vitamin D, but may replace better iron sources such as meat. We investigated if intake of 300 g/week oily fish was achievable in children and how it affected their nutrient status. Additionally, we validated a fish food frequency questionnaire (FFQ) by correlations against EPA + DHA in red blood cells (RBC). METHODS: In a randomised 12-week trial, 199 children (8-9 years) received oily fish or poultry (control) to be eaten five times/week. We measured dietary intake and analysed fasting RBC EPA + DHA, serum 25-hydroxyvitamin D (25(OH)D), blood haemoglobin and plasma ferritin. RESULTS: 197 (99%) children completed the study. The median (25th-75th percentile) intake was 375 (325-426) and 400 (359-452) g/week oily fish and poultry, respectively. The fish group increased their intake of EPA + DHA by 749 (593-891) mg/day and vitamin D by 3.1 (1.6-3.8) µg/day. Endpoint RBC EPA + DHA was 2.3 (95% CI 1.9; 2.6) fatty acid %-point higher than the poultry group (P < 0.001). The fish group avoided the expected 25(OH)D winter decline (P < 0.001) and had 23%-point less vitamin D insufficiency (winter subgroup, n = 82). Haemoglobin and ferritin decreased slightly in both groups (P < 0.05), but the number of children with low values did not change (P > 0.14). FFQ estimates moderately reflected habitual intake (r = 0.28-0.35) and sufficiently captured intervention-introduced changes in intake (r > 0.65). CONCLUSION: Oily fish intake of 300 g/week was achievable and improved children's EPA + DHA and 25(OH)D status, without markedly compromising iron status. These results justify public health initiatives focusing on children's fish intake.

FADS and PPARG2 Single Nucleotide Polymorphisms are Associated with Plasma Lipids in 9-Mo-Old Infants.

BACKGROUND: Dietary intake of polyunsaturated fatty acids (PUFAs), e.g., linoleic acid and n-3 (ω-3) long-chain PUFAs, has been shown in adults to affect plasma cholesterol and triglycerides (TGs), respectively. Little is known about the effects of PUFAs on plasma lipids in early life. OBJECTIVE: The aim of this study was to explore the associations between plasma concentrations of total, LDL, and HDL cholesterol and TGs in infants and 2 single nucleotide polymorphisms (SNPs) in the fatty acid desaturase genes (FADS) oppositely associated with docosahexaenoic acid (rs1535 and rs174448) and potential effect modification by a functional peroxisome proliferator-activated receptor-γ2 gene variant (PPARG2 Pro12Ala). METHODS: In 9-mo-old infants (n = 561) from 3 Danish cohorts, we analyzed associations between plasma lipids, erythrocyte PUFAs, and FADS SNPs, and interactions with PPARG2 Pro12Ala genotype, by multiple linear regression. We also examined potential effect modification by breastfeeding, as 46% of the infants were still being breastfed. RESULTS: Minor allele carriage of rs174448 was associated with lower total cholesterol (difference: -0.22 mmol/L; 95% CI: -0.37, -0.06 mmol/L; P = 0.006) and LDL cholesterol (difference: -0.15 mmol/L; 95% CI: -0.29, -0.01 mmol/L; P = 0.035), but no associations were observed with TGs or for rs1535. Minor allele carriage of both FADS SNPs was associated with 1 SD lower HDL cholesterol, but only in currently breastfed infants (rs174448 × breastfeeding, P = 0.080; rs1535 × breastfeeding, P = 0.030) and PPARG2 minor allele carriers (rs174448 × PPARG2, P = 0.001; rs1535 × PPARG2, P = 0.004). Erythrocyte arachidonic acid and eicosapentaenoic acid were inversely associated with LDL cholesterol [estimated effect (ß): -0.3 mmol/L; 95% CI: -0.06, -0.00 mmol/L per percentage of fatty acids (FA%); P = 0.035] and TGs (ß: -0.23 mmol/L; 95% CI: -0.41, -0.05 mmol/L per FA%; P = 0.015), respectively. CONCLUSIONS: The observed associations with FADS variants indicate that PUFAs are involved in plasma lipid regulation in 9-mo-old infants. Observed FADS SNP differences and interactions with breastfeeding and PPARG2 warrant additional studies to explore the effects of individual FADS SNPs on PUFA status and potential genetic modification of dietary PUFA effects.

Winter vitamin D3 supplementation does not increase muscle strength, but modulates the IGF-axis in young children.

PURPOSE: To explore whether muscle strength, the insulin-like growth factor axis (IGF-axis), height, and body composition were associated with serum 25-hydroxyvitamin D [25(OH)D] and affected by winter vitamin D supplementation in healthy children, and furthermore to explore potential sex differences. METHODS: We performed a double-blind, placebo-controlled, dose-response winter trial at 55ºN. A total of 117 children aged 4-8 years were randomly assigned to either placebo, 10, or 20 µg/day of vitamin D3 for 20 weeks. At baseline and endpoint, we measured muscle strength with handgrip dynamometer, fat mass index (FMI), fat free mass index (FFMI), height, plasma IGF-1, IGF-binding protein 3 (IGFBP-3), and serum 25(OH)D. RESULTS: At baseline, serum 25(OH)D was positively associated with muscle strength, FFMI, and IGFBP-3 in girls only (all p < 0.01). At endpoint, baseline-adjusted muscle strength, FMI and FFMI did not differ between intervention groups. However, baseline-adjusted IGF-1 and IGFBP-3 were higher after 20 µg/day compared to placebo (p = 0.043 and p = 0.006, respectively) and IGFBP-3 was also higher after 20 µg/day compared to 10 µg/day (p = 0.011). Children tended to be taller after 20 µg/day compared to placebo (p = 0.064). No sex interactions were seen at endpoint. CONCLUSIONS: Avoiding the winter-related decline in serum 25(OH)D may influence IGF-1 and IGFBP-3 in children. Larger trials are required to confirm these effects, and the long-term implication for linear growth.

Winter Cholecalciferol Supplementation at 51°N Has No Effect on Markers of Cardiometabolic Risk in Healthy Adolescents Aged 14-18 Years.

Background: Epidemiologic studies have supported inverse associations between low serum 25-hydroxyvitamin D [25(OH)D] and cardiometabolic risk markers, but few randomized trials have investigated the effect of vitamin D supplementation on these markers in adolescents. Objective: The objective of this study was to investigate the effect of winter-time cholecalciferol (vitamin D3) supplementation on cardiometabolic risk markers in white, healthy 14- to 18-y-old adolescents in the UK (51°N) as part of the ODIN Project. Methods: In a dose-response trial, 110 adolescents (mean ± SD age: 15.9 ± 1.4 y; 43% male; 81% normal weight) were randomly assigned to receive 0, 10 or 20 µg/d vitamin D3 for 20 wk (October-March). Cardiometabolic risk markers including BMI-for-age z score (BMIz), waist circumference, systolic and diastolic blood pressure, fasting plasma triglycerides, cholesterol (total, HDL, LDL, and total:HDL), and glucose were measured at baseline and endpoint as secondary outcomes, together with serum 25(OH)D. Intervention effects were evaluated in linear regression models as between-group differences at endpoint, adjusted for the baseline value of the outcome variable and additionally for age, sex, Tanner stage, BMIz, and baseline serum 25(OH)D. Results: Mean ± SD baseline serum 25(OH)D was 49.1 ± 12.3 nmol/L and differed between groups at endpoint with concentrations of 30.7 ± 8.6, 56.6 ± 12.4, and 63.9 ± 10.6 nmol/L in the 0, 10, and 20 µg/d groups, respectively (P ≤ 0.001). Vitamin D3 supplementation had no effect on any of the cardiometabolic risk markers (all P > 0.05), except for lower HDL (-0.12 mmol/L; 95% CI: -0.21, 0.04 mmol/L; P = 0.003) and total cholesterol (-0.21 mmol/L; 95% CI: -0.42, 0.00 mmol/L; P = 0.05) in the 20 µg/d than in the 10 µg/d group, which disappeared in the fully adjusted analysis (P = 0.27 and P = 0.30, respectively). Conclusions: Supplementation with vitamin D3 at 10 and 20 µg/d, which increased serum 25(OH)D concentrations during the winter-time, had no effect on markers of cardiometabolic risk in healthy 14- to 18-y-old adolescents. This trial was registered at clinicaltrials.gov as NCT02150122.

Winter Cholecalciferol Supplementation at 55°N Has No Effect on Markers of Cardiometabolic Risk in Healthy Children Aged 4-8 Years.

Background: Low serum 25-hydroxyvitamin D [25(OH)D] has been associated with unfavorable cardiometabolic risk profiles in many observational studies in children, but very few randomized controlled trials have investigated this. Objective: We explored the effect of winter-time cholecalciferol (vitamin D3) supplementation on cardiometabolic risk markers in young, white, 4- to 8-y-old healthy Danish children (55°N) as part of the pan-European ODIN project. Methods: In the ODIN Junior double-blind, placebo-controlled, dose-response trial, 119 children (mean ± SD age: 6.7 ± 1.5 y; 36% male; 82% normal weight) were randomly allocated to 0, 10 or 20 µg/d of vitamin D3 for 20 wk (October-March). Cardiometabolic risk markers including BMI-for-age z score (BMIz), waist circumference, systolic and diastolic blood pressure, serum triglycerides and cholesterol (total, LDL, HDL, and total:HDL), plasma glucose and insulin, and whole-blood glycated hemoglobin were measured at baseline and endpoint as secondary outcomes together with serum 25(OH)D. Intervention effects were evaluated in linear regression models as between-group differences at endpoint adjusted for baseline value of the outcome, and additionally for age, sex, baseline serum 25(OH)D, BMIz, time since breakfast, and breakfast content. Results: Mean ± SD serum 25(OH)D was 56.7 ± 12.3 nmol/L at baseline and differed between groups at endpoint with concentrations of 31.1 ± 7.5, 61.8 ± 10.6, and 75.8 ± 11.5 nmol/L in the 0-, 10-, and 20 µg/d groups, respectively (P < 0.0001). Vitamin D3 supplementation had no effect on any of the cardiometabolic risk markers in analyses adjusted for baseline value of the outcome (all P ≥ 0.05), and additional covariate adjustment did not change the results notably. Conclusions: Preventing the winter decline in serum 25(OH)D with daily vitamin D3 supplementation of 10 or 20 µg had no cardiometabolic effects in healthy 4- to 8-y-old Danish children. This trial was registered at www.clinicaltrials.gov as NCT02145195.

Sun behaviour and physical activity associated with autumn vitamin D status in 4-8-year-old Danish children.

OBJECTIVE: To explore determinants of serum 25-hydroxyvitamin D (s-25(OH)D) during autumn in young, Caucasian children not consuming vitamin D-fortified foods or supplements, and explore differences in sun behaviours between pre-school and school children. DESIGN: In September-October, s-25(OH)D was measured by LC-MS/MS; physical activity, sun behaviours and vitamin D intake were assessed with questionnaires. SETTING: Baseline data from the ODIN Junior trial at 55°N. SUBJECTS: Children aged 4-8 years (n 130), of whom 96% gave blood samples. RESULTS: Mean s-25(OH)D was 56·8 (sd 12·5) nmol/l and positively associated with fat-free mass index (P=0·014). Children being active 6-7 h/week had 5·6 (95% CI 1·1, 10·0) nmol/l higher s-25(OH)D than less active children (P=0·014). Children seeking shade sometimes or rarely/never had 7·0 (95% CI 1·2, 12·9; P=0·018) and 7·2 (95% CI 0·8, 13·6; P=0·028) nmol/l higher s-25(OH)D, respectively, than children always/often seeking shade. Pre-school children had more sun-safe behaviour than school children in terms of use of a hat, sunscreen and sunscreen sun protection factor (P<0·05). In school but not pre-school children, using a hat rarely/never was associated with 12·1 (95% CI 2·5, 21·7; P=0·014) nmol/l higher s-25(OH)D v. always/often (P interaction=0·019). Vitamin D intake was not associated with s-25(OH)D (P=0·241). CONCLUSIONS: Physical activity and sun behaviours are associated with s-25(OH)D in young children. Identifying factors influencing autumn s-25(OH)D is relevant to optimize levels before sun exposure diminishes. Strategies to reduce risk of inadequacy should consider risk of skin cancer and sunburn, and could include fortification and/or vitamin D supplementation.

Whole-Grain Intake, Reflected by Dietary Records and Biomarkers, Is Inversely Associated with Circulating Insulin and Other Cardiometabolic Markers in 8- to 11-Year-Old Children.

Background: Whole-grain consumption seems to be cardioprotective in adults, but evidence in children is limited.Objective: We investigated whether intakes of total whole grain and dietary fiber as well as specific whole grains were associated with fat mass and cardiometabolic risk profile in children.Methods: We collected cross-sectional data on parental education, puberty, diet by 7-d records, and physical activity by accelerometry and measured anthropometry, fat mass index by dual-energy X-ray absorptiometry, and blood pressure in 713 Danish children aged 8-11 y. Fasting blood samples were obtained and analyzed for alkylresorcinols, biomarkers of whole-grain wheat and rye intake, HDL and LDL cholesterol, triacylglycerols, insulin, and glucose. Linear mixed models included puberty, parental education, physical activity, and intakes of energy, fruit and vegetables, saturated fat, and n-3 (ω-3) polyunsaturated fatty acids.Results: Median (IQR) whole-grain and dietary fiber intakes were 52 g/d (35-72 g/d) and 17 g/d (14-22 g/d), respectively. Fourteen percent of children were overweight or obese and most had low-risk cardiometabolic profiles. Dietary whole-grain and fiber intakes were not associated with fat mass index but were inversely associated with serum insulin [both P < 0.01; e.g., with 0.68 pmol/L (95% CI: 0.26, 1.10 pmol/L) lower insulin · g whole grain-1 · MJ-1]. Whole-grain oat intake was inversely associated with fat mass index, systolic blood pressure, and LDL cholesterol (all P < 0.05) as well as insulin (P = 0.003), which also tended to be inversely associated with whole-grain rye intake (P = 0.11). Adjustment for fat mass index did not change the associations. The C17-to-C21 alkylresorcinol ratio, reflecting whole-grain rye to wheat intake, was inversely associated with insulin (P < 0.001).Conclusions: Higher whole-grain intake was associated with lower serum insulin independently of fat mass in 8- to 11-y-old Danish children. Whole-grain oat intake was linked to an overall protective cardiometabolic profile, and whole-grain rye intake was marginally associated with lower serum insulin. This supports whole grains as healthy dietary components in childhood. This trial was registered at clinicaltrials.gov as NCT01577277.

Common genetic variants are associated with lower serum 25-hydroxyvitamin D concentrations across the year among children at northern latitudes.

In a longitudinal study including 642 healthy 8-11-year-old Danish children, we investigated associations between vitamin D dependent SNP and serum 25-hydroxyvitamin D (25(OH)D) concentrations across a school year (August-June). Serum 25(OH)D was measured three times for every child, which approximated measurements in three seasons (autumn, winter, spring). Dietary and supplement intake, physical activity, BMI and parathyroid hormone were likewise measured at each time point. In all, eleven SNP in four vitamin D-related genes: Cytochrome P450 subfamily IIR1 (CYP2R1); 7-dehydrocholesterol reductase/nicotinamide adenine dinucleotide synthetase-1(DHCR7/NADSYN1); group-specific complement (GC); and vitamin D receptor were genotyped. We found minor alleles of CYP2R1 rs10500804, and of GC rs4588 and rs7041 to be associated with lower serum 25(OH)D concentrations across the three seasons (all P<0·01), with estimated 25(OH)D differences of -5·8 to -10·6 nmol/l from major to minor alleles homozygosity. In contrast, minor alleles homozygosity of rs10741657 and rs1562902 in CYP2R1 was associated with higher serum 25(OH)D concentrations compared with major alleles homozygosity (all P<0·001). Interestingly, the association between season and serum 25(OH)D concentrations was modified by GC rs7041 (P interaction=0·044), observed as absence of increase in serum 25(OH)D from winter to spring among children with minor alleles homozygous genotypes compared with the two other genotypes of rs7041 (P<0·001). Our results suggest that common genetic variants are associated with lower serum 25(OH)D concentrations across a school year. Potentially due to modified serum 25(OH)D response to UVB sunlight exposure. Further confirmation and paediatric studies investigating vitamin D-related health outcomes of these genotypic differences are needed.

Validation of Reported Whole-Grain Intake from a Web-Based Dietary Record against Plasma Alkylresorcinol Concentrations in 8- to 11-Year-Olds Participating in a Randomized Controlled Trial.

BACKGROUND: Whole-grain (WG) intake is important for human health, but accurate intake estimation is challenging. Use of a biomarker for WG intake provides a possible way to validate dietary assessment methods. OBJECTIVE: Our aim was to validate WG intake from 2 diets reported by children, using plasma alkylresorcinol (AR) concentrations, and to investigate the 3-mo reproducibility of AR concentrations and reported WG intake. METHODS: AR concentrations were analyzed in fasting blood plasma samples, and WG intake was estimated in a 7-d web-based diary by 750 participants aged 8-11 y in a 2 school meal × 3 mo crossover trial. Reported WG intake and plasma AR concentrations were compared when children ate their usual bread-based lunch (UBL) and when served a hot lunch meal (HLM). Correlations and cross-classification were used to rank subjects according to intake. The intraclass correlation coefficients (ICCs) between subjects' measurements at baseline and after the UBL were used to assess reproducibility. RESULTS: Correlations between reported WG wheat + rye intake and plasma AR were 0.40 and 0.37 (P < 0.001) for the UBL and the HLM diets, and 78% and 77% were classified in the same or adjacent quartiles for the UBL and HLM diets, respectively. The ICC over 3 mo was 0.47 (95% CI: 0.38, 0.55) for plasma total ARs and 0.64 (95% CI: 0.58, 0.70) for reported WG intake. Correlations were higher when using the AR C17:0 homolog as a biomarker, reflecting rye intake instead of plasma total ARs [UBL: r = 0.47; HLM: r = 0.43, P < 0.001; ICC = 0.51 (95% CI: 0.43, 0.59)]. CONCLUSIONS: Self-reported WG wheat + rye intake among children showed moderate correlations with plasma AR concentrations. Substantial intraindividual variation was found in WG intake and plasma AR concentrations. The AR homolog C17:0 may be used as a biomarker for WG intake when the WG intake primarily comes from rye as in the present study. This trial was registered at clinicaltrials.gov as NCT01457794.

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/ m(2)/y) and FFMI (average: 0.17 kg/m(2)/y) showed similar trends. In contrast, FMI was above the average (0.38 kg/m(2)/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.

Fish oil supplementation from 9 to 18 months of age affects the insulin-like growth factor axis in a sex-specific manner in Danish infants.

Several studies have investigated the effects of fish oil (FO) on infant growth, but little is known about the effects of FO and sex on insulin-like growth factor-1 (IGF-1), the main regulator of growth in childhood. We explored whether FO v. sunflower oil (SO) supplementation from 9 to 18 months of age affected IGF-1 and its binding protein-3 (IGFBP-3) and whether the potential effects were sex specific. Danish infants (n 115) were randomly allocated to 5 ml/d FO (1·2 g/d n-3 long-chain PUFA (n-3 LCPUFA)) or SO. We measured growth, IGF-1, IGFBP-3 and erythrocyte EPA, a biomarker of n-3 LCPUFA intake and status, at 9 and 18 months. Erythrocyte EPA increased strongly with FO compared with SO (P<0·001). There were no effects of FO compared with SO on IGF-1 in the total population, but a sex × group interaction (P=0·02). Baseline-adjusted IGF-1 at 18 months was 11·1 µg/l (95% CI 0·4, 21·8; P=0·04) higher after FO compared with SO supplementation among boys only. The sex × group interaction was borderline significant in the model of IGFBP-3 (P=0·09), with lower IGFBP-3 with FO compared with SO among girls only (P=0·03). The results were supported by sex-specific dose-response associations between changes in erythrocyte EPA and changes in IGF-1 and IGFBP-3 (both P<0·03). Moreover, IGF-1 was sex specifically associated with BMI and length. In conclusion, FO compared with SO resulted in higher IGF-1 among boys and lower IGFBP-3 among girls. The potential long-term implications for growth and body composition should be investigated further.

Vitamin D status and its determinants during autumn in children at northern latitudes: a cross-sectional analysis from the optimal well-being, development and health for Danish children through a healthy New Nordic Diet (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) (ß -2·9; 95 % CI -5·1, -0·7 nmol/l), female sex (ß -3·3; 95 % CI -5·9, -0·7 nmol/l), sampling in October (ß -5·2; 95 % CI -10·1, -0·4 nmol/l) and November (ß -13·3; 95 % CI -17·7, -9·1), and non-white ethnicity (ß -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 (ß -16·3; 95 % CI -21·9, -10·7) (P<0·001) (P interaction=0·003). Moderate-to-vigorous physical activity (MVPA) (min/d) (ß 0·06; 95 % CI 0·01, 0·12), outdoor walking during school hours (min/week) (ß 0·4; 95 % CI 0·1, 0·6) and intake of vitamin D-containing supplements ≥3 d/week (ß 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.

Associations between school meal-induced dietary changes and metabolic syndrome markers in 8-11-year-old Danish children.

PURPOSE: We recently showed that provision of Nordic school meals rich in fish, vegetables and potatoes and with reduced intakes of fat improved blood pressure, insulin resistance assessed by the homeostatic model (HOMA-IR), and plasma triacylglycerol despite increasing waist circumference in Danish 8-11-year-olds. This study explored whether intake or biomarkers of key dietary components in the schools meals were associated with these metabolic syndrome (MetS) markers during the 6-month intervention. METHODS: Data from 7-day dietary records and measurements of whole-blood docosahexaenoic acid (DHA, 22:6n-3), blood pressure, fasting blood MetS markers, waist circumference and android/total fat mass assessed by dual-energy X-ray absorptiometry collected at baseline, 3 and 6 months from 523 children were analyzed in linear mixed-effects models adjusted for puberty, growth and fasting. RESULTS: After adjustment for multiple testing, whole-blood DHA was negatively associated with HOMA-IR (P < 0.001) and triacylglycerol (P < 0.0001). Potato intake was positively associated with waist circumference (P < 0.01), but not with android/total fat mass (P = 0.94). Intakes of whole-grain as well as dietary fiber, protein and fat were not associated with any of the MetS markers. CONCLUSIONS: DHA in whole-blood, an indicator of DHA and fish intake, seemed to be the main diet-related predictor of the beneficial effects of the school meals on MetS markers. Increased potato intake was associated with increased waist circumference, but this may not only be due to an increase in abdominal fat, as no association was seen with fat distribution.