Non-Western immigrant children have lower 25-hydroxyvitamin D than children from Western families.

OBJECTIVE: To determine if children aged 1-6 years from non-Western immigrant families have lower serum 25-hydroxyvitamin D (25(OH)D) levels than children from Western-born families and examine which factors influence this relationship. DESIGN: Cross-sectional study. SETTING: Toronto, Canada. SUBJECTS: Healthy children (n 1540) recruited through the TARGet Kids! practice-based research network. Serum 25(OH)D concentrations of non-Western immigrants were compared with those of children from Western-born families. Children from non-Western immigrant families were defined as those born, or their parents were born, outside a Western country. Univariate and multiple linear regression analyses were used to identify factors which might influence this relationship. RESULTS: Median age was 36 months, 51 % were male, 86 % had 'light' skin pigmentation, 55 % took vitamin D supplements, mean cow's milk intake was 1·8 cups/d and 27 % were non-Western immigrants. Median serum 25(OH)D concentration was 83 nmol/l, with 5 % having 25(OH)D < 50 nmol/l. Univariable analysis revealed that non-Western immigrant children had serum 25(OH)D lower by 4 (95 % CI 1·3, 8·0) nmol/l (P = 0·006) and increased odds of 25(OH)D < 50 nmol/l (OR = 1·9; 95 % CI 1·3, 2·9). After adjustment for known vitamin D determinants the observed difference attenuated to 0·04 (95 % CI -4·8, 4·8) nmol/l (P = 0·99), with higher cow's milk intake (P < 0·0001), vitamin D supplementation (P < 0·0001), summer season (P = 0·008) and increased age (P = 0·04) being statistically significant covariates. Vitamin D supplementation was the strongest explanatory factor of the observed difference. CONCLUSIONS: There is an association between non-Western immigration and lower 25(OH)D in early childhood. This difference appears related to known vitamin D determinants, primarily vitamin D supplementation, representing opportunities for intervention.

Association between serum cholesterol and eating behaviours during early childhood: a cross-sectional study.

BACKGROUND: Modifiable behaviours during early childhood may provide opportunities to prevent disease processes before adverse outcomes occur. Our objective was to determine whether young children's eating behaviours were associated with increased risk of cardiovascular disease in later life. METHODS: In this cross-sectional study involving children aged 3-5 years recruited from 7 primary care practices in Toronto, Ontario, we assessed the relation between eating behaviours as assessed by the NutriSTEP (Nutritional Screening Tool for Every Preschooler) questionnaire (completed by parents) and serum levels of non-high-density lipoprotein (HDL) cholesterol, a surrogate marker of cardiovascular risk. We also assessed the relation between dietary intake and serum non-HDL cholesterol, and between eating behaviours and other laboratory indices of cardiovascular risk (low-density lipoprotein [LDL] cholesterol, apolipoprotein B, HDL cholesterol and apoliprotein A1). RESULTS: A total of 1856 children were recruited from primary care practices in Toronto. Of these children, we included 1076 in our study for whom complete data and blood samples were available for analysis. The eating behaviours subscore of the NutriSTEP tool was significantly associated with serum non-HDL cholesterol (p = 0.03); for each unit increase in the eating behaviours subscore suggesting greater nutritional risk, we saw an increase of 0.02 mmol/L (95% confidence interval [CI] 0.002 to 0.05) in serum non-HDL cholesterol. The eating behaviours subscore was also associated with LDL cholesterol and apolipoprotein B, but not with HDL cholesterol or apolipoprotein A1. The dietary intake subscore was not associated with non-HDL cholesterol. INTERPRETATION: Eating behaviours in preschool-aged children are important potentially modifiable determinants of cardiovascular risk and should be a focus for future studies of screening and behavioural interventions.

Parent reported nutritional risk and laboratory indices of cardiometabolic risk and in preschool-aged children.

BACKGROUND: Eating habits formed during childhood may contribute to the increasing prevalence of cardiometabolic disorders. Assessing nutritional risk in young children may help to prevent later cardiometabolic disease. The objective of this study was to determine whether parent-reported nutritional risk in preschool-aged children was associated with laboratory indices of cardiometabolic risk, namely leptin and insulin. METHODS: In this cross-sectional study, the relationship between nutritional risk as determined by the parent-completed NutriSTEP® questionnaire was assessed and compared to the serum leptin and insulin concentrations, hormones involved in regulation of food intake and biomarkers of adiposity and cardiometabolic risk. The community-based primary care research network for children in Toronto, Canada (TARGet Kids!) was used. The participants were children aged 3-5 years recruited from TARGet Kids! A total of 1856 children were recruited from seven primary care practices. Of these, 1086 children completed laboratory testing. Laboratory data for leptin and insulin were available for 714 and 1054 of those individuals, respectively. RESULTS: The total NutriSTEP® score was significantly associated with serum leptin concentrations (p=0.003); for each unit increase in the total NutriSTEP® score, there was an increase of 0.01 ng/mL (95% confidence interval [CI] 0.004-0.018) in serum leptin concentrations after adjusting for potential confounders. The total NutriSTEP® score was not significantly associated with serum insulin concentration. CONCLUSIONS: Parent reported nutritional risk is associated with serum leptin, but not insulin, concentrations in preschool-aged children. The NutriSTEP® questionnaire may be an effective tool for predicting future cardiometabolic risk in preschool-aged children.

Mandatory labeling requirements and over-the-counter cough and cold medication use in early childhood.

OBJECTIVES: Due to rare but severe adverse events, Health Canada in October 2009 required manufacturers to relabel over-the-counter (OTC) cough and cold medication (CCM) to state that the products should not be used in children <6 years of age. The main objective of this study was to determine whether this labeling standard decreased OTC CCM use among young children with a recent cough, cold or flu. METHODS: An interrupted time series study was conducted using data from the TARGet Kids! practice-based research network. A total of 3,515 healthy children 1-5 years of age were recruited from 2008-2011; of these, 1,072 had a cough, cold or flu in the previous month. Parents completed a standardized survey instrument. For the primary analysis, use of OTC CCMs prior to and after October 1, 2009 was compared using time series analyses. For the secondary analysis, multivariable logistic regression was used to identify predictors of recent OTC CCM use. RESULTS: OTC CCM use was reported in 222 of 1,072 (20.7%) children with a cough, cold or flu within the previous month. OTC CCM use declined from 22.2% to 17.8% following the October 2009 Health Canada labeling standard (p = 0.014). Maternal age <35 years (OR 1.49; 95% CI: 1.05-2.13) and having older siblings (OR 1.65; 95% CI: 1.16-2.35) were independently associated with OTC CCM use. CONCLUSION: Labeling legislation against OTC CCM use for children <6 years resulted in a small decrease in OTC CCM use. Stronger measures may be needed to curtail OTC CCM use, particularly for younger parents and those with multiple children.

Association between Vitamin D and Circulating Lipids in Early Childhood.

Vitamin D is associated with established cardiovascular risk factors such as low density lipoprotein (LDL) in adults. It is unknown whether these associations are present in early childhood. To determine whether serum 25-hydroxyvitamin D (25(OH)D) is associated with serum non-high density lipoprotein (non-HDL) cholesterol during early childhood we conducted a cross-sectional study of children aged 1 to 5 years. Healthy children were recruited through the TARGet Kids! practice based research network from 2008-2011 (n=1,961). The associations between 25(OH)D and non-fasting non-HDL cholesterol (the primary endpoint), total cholesterol, triglycerides, HDL, and low density lipoprotein (LDL) cholesterol, were evaluated using multiple linear regression adjusted for age, sex, skin pigmentation, milk intake, vitamin D supplementation, season, body mass index, outdoor play, and screen time. Each 10 nmol/L increase in 25(OH)D was associated with a decrease in non-HDL cholesterol concentration of -0.89 mg/dl (95% CI: -1.16,-0.50), total cholesterol of -1.08 mg/dl (95%CI: -1.49,-0.70), and triglycerides of -2.34 mg/dl (95%CI: -3.23,-1.45). The associations between 25(OH)D and LDL and HDL were not statistically significant. 25(OH)D concentrations were inversely associated with circulating lipids in early childhood, suggesting that vitamin D exposure in early life may be an early modifiable risk factor for cardiovascular disease.

Cohort Profile: The Applied Research Group for Kids (TARGet Kids!).

The Applied Research Group for Kids (TARGet Kids!) is an ongoing open longitudinal cohort study enrolling healthy children (from birth to 5 years of age) and following them into adolescence. The aim of the TARGet Kids! cohort is to link early life exposures to health problems including obesity, micronutrient deficiencies and developmental problems. The overarching goal is to improve the health of Canadians by optimizing growth and developmental trajectories through preventive interventions in early childhood. TARGet Kids!, the only child health research network embedded in primary care practices in Canada, leverages the unique relationship between children and families and their trusted primary care practitioners, with whom they have at least seven health supervision visits in the first 5 years of life. Children are enrolled during regularly scheduled well-child visits. To date, we have enrolled 5062 children. In addition to demographic information, we collect physical measurements (e.g. height, weight), lifestyle factors (nutrition, screen time and physical activity), child behaviour and developmental screening and a blood sample (providing measures of cardiometabolic, iron and vitamin D status, and trace metals). All data are collected at each well-child visit: twice a year until age 2 and every year until age 10. Information can be found at: http://www.targetkids.ca/contact-us/.

Evaluating the accuracy of a geographic closed-ended approach to ethnicity measurement, a practical alternative.

PURPOSE: Measuring ethnicity accurately is important for identifying ethnicity variations in disease risk. We evaluated the degree of agreement and accuracy of maternal ethnicity measured using the new standardized closed-ended geographically based ethnicity question and geographic reclassification of open-ended ethnicity questions from the Canadian census. METHODS: A prospectively designed study of respondent agreement of mothers of healthy children aged 1-5 years recruited through the TARGet Kids! practice-based research network. For the primary analysis, the degree of agreement between geographic reclassification of the Canadian census maternal ethnicity variables and the new geographically based closed-ended maternal ethnicity variable completed by the same respondent was evaluated using a kappa analysis. RESULTS: Eight hundred sixty-two mothers who completed both measures of ethnicity were included in the analysis. The kappa agreement statistic for the two definitions of maternal ethnicity was 0.87 (95% confidence interval, 0.84-0.90) indicating good agreement. Overall accuracy of the measurement was 93%. Sensitivity and specificity ranged from 83% to 100% and 96% to 100%, respectively. CONCLUSIONS: The new standardized closed-ended geographically based ethnicity question represents a practical alternative to widely used open-ended ethnicity questions. It may reduce risk of misinterpretation of ethnicity by respondents, simplify analysis, and improve the accuracy of ethnicity measurement.

The relationship between cow's milk and stores of vitamin D and iron in early childhood.

OBJECTIVE: To examine the association between cow's milk intake on both vitamin D and iron stores in healthy urban preschoolers. METHODS: Healthy children 2 to 5 years of age were recruited from December 2008 through December 2010 through the TARGet Kids! practice-based research network. Cow's milk intake was measured by parental report. Vitamin D and iron stores were measured by using serum 25-hydroxyvitamin D and ferritin. Bivariate multivariable linear regression was used to examine the effect of cow's milk intake simultaneously on 25-hydroxyvitamin D and serum ferritin. Analyses were stratified by important clinical variables including skin pigmentation, bottle feeding, vitamin D supplementation, and season. RESULTS: Among 1311 children, increasing cow's milk consumption was associated with decreasing serum ferritin (P < .0001) and increasing 25-hydroxyvitamin D (P ≤ .0001). Two cups (500 mL) of cow's milk per day maintained 25-hydroxyvitamin D >75 nmol/L with minimal negative effect on serum ferritin for most children. Children with darker skin pigmentation not receiving vitamin D supplementation during the winter required 3 to 4 cups of cow's milk per day to maintain 25-hydroxyvitamin D >75 nmol/L. Cow's milk intake among children using a bottle did not increase 25-hydroxyvitamin D and resulted in more dramatic decreases in serum ferritin. CONCLUSIONS: There is a trade-off between increasing 25-hydroxyvitamin D and decreasing serum ferritin with increasing milk intake. Two cups of cow's milk per day appears sufficient to maintain healthy vitamin D and iron stores for most children. Wintertime vitamin D supplementation was particularly important among children with darker skin pigmentation.

Modifiable determinants of serum 25-hydroxyvitamin D status in early childhood: opportunities for prevention.

OBJECTIVES To determine the effect of modifiable dietary intake variables (current vitamin D supplementation and daily cow's milk intake) on 25-hydroxyvitamin D level in early childhood and to evaluate the relationship between these modifiable dietary factors and other largely nonmodifiable determinants of vitamin D status including skin pigmentation and season. DESIGN Cross-sectional study. SETTING Primary care pediatric and family medicine practices participating in the TARGet Kids! practice-based research network in Toronto, Ontario, Canada. PARTICIPANTS From December 2008 to June 2011, healthy children 1 to 5 years of age were recruited during a routine physician's visit. INTERVENTIONS Survey, anthropometric measurements, and laboratory data were collected. A multivariable linear regression model was developed to examine the independent effects of vitamin D supplementation and daily volume of cow's milk on 25-hydroxyvitamin D level. MAIN OUTCOME MEASURES 25-Hydroxyvitamin D level. RESULTS Blood was obtained in 1898 children. Two modifiable dietary intake variables, vitamin D supplementation and cow's milk, increased 25-hydroxyvitamin D level by 3.4 ng/mL (95% CI, 2-4 ng/mL) and 1.6 ng/mL per 250-mL cup per day (95% CI, 1-2 ng/mL), respectively. Two nonmodifiable variables reflecting cutaneous vitamin D synthesis (skin pigmentation and season) were also strongly associated with 25-hydroxyvitamin D status but accounted for a much smaller proportion of the explained variation in 25-hydroxyvitamin D level. The effect of vitamin D supplementation and milk intake on 25-hydroxyvitamin D level appeared similar regardless of skin pigmentation or season. CONCLUSION Two modifiable dietary intake variables (vitamin D supplementation and cow's milk intake) are the most important determinants of 25-hydroxyvitamin D status in early childhood.

Association between total duration of breastfeeding and iron deficiency.

OBJECTIVE: To determine whether there is an association between the total breastfeeding duration and iron stores, iron deficiency, and iron deficiency anemia in healthy urban children. METHODS: A cross-sectional study of healthy children, aged 1 to 6 years, seen for primary health care between December 2008 and July 2011 was conducted through the TARGet Kids! practice-based research network. Univariate and adjusted regression analyses were used to evaluate an association between total breastfeeding duration and serum ferritin, iron deficiency, and iron deficiency anemia. RESULTS: Included were 1647 healthy children (median age 36 months) with survey, anthropometric, and laboratory data. An association was found between increasing duration of breastfeeding and lower serum ferritin (P = .0015). Adjusted logistic regression analysis revealed the odds of iron deficiency increased by 4.8% (95% confidence interval: 2%-8%) for each additional month of breastfeeding. Exploratory analysis suggested an increasing cumulative probability of iron deficiency with longer total breastfeeding duration with an adjusted odds ratio of 1.71 (95% confidence interval: 1.05-2.79) for iron deficiency in children breastfed over versus under 12 months of age. The relationship between total breastfeeding duration and iron deficiency anemia did not meet statistical significance. CONCLUSIONS: Increased total breastfeeding duration is associated with decreased iron stores, a clinically important association warranting additional investigation.

Paediatric obesity research in early childhood and the primary care setting: the TARGet Kids! research network.

Primary paediatric health care is the foundation for preventative child health. In light of the recent obesity epidemic, paediatricians find themselves at the frontline of identification and management of childhood obesity. However, it is well recognized that evidence based approaches to obesity prevention and subsequent translation of this evidence into practice are critically needed. This paper explores the role of primary care in obesity prevention and introduces a novel application and development of a primary care research network in Canada--TARGet Kids!--to develop and translate an evidence-base on effective screening and prevention of childhood obesity.