Update on the metabolic syndrome in children

[Physical activity in preventing metabolic syndrome in children]

Metabolic syndrome defined as the joint manifestation on the same subject of several risk factors (at least 3 in the majority of definitions) within the following parameters : hypertriglyceridemia, hypertension, abdominal obesity, low concentration of HDL-Cholesterol (HDL-C), and high fasting blood glucose is increasingly reported in children, mainly in the presence of overweight/obesity. In fact, up to 50 % of overweight/obese children can be affected by this syndrome. Furthermore, the metabolic syndrome acquired during childhood has been shown to impact highly into adulthood including by its clinical complications such as type 2 diabetes or cardiovascular diseases. Among the practical preventive and therapeutic measures to be taken in children, physical activity appears to be an option of choice. This review indicates that physical activity programs based either on aerobic exercise, resistance training, or a combination of these 2 types of activity may promote insulin sensibility and weaken or suppress the metabolic syndrome of children. More interestingly, usual physical activity including free-living activities of an intensity equivalent to a brisk walking should be encouraged earlier among children for its positive influence on parameters involved in the metabolic syndrome.

Relationship between obesity and metabolic syndrome among Argentinean elementary school children

BACKGROUND

Argentina has experienced marked increases in the prevalence of childhood overweight (OW)/obesity over the last few decades.

OBJECTIVES

We examined (1) the distribution of the mean values of lipids, glucose, and HOMA-IR according to the presence of OW/obesity, age, and sex and (2) the association between metabolic syndrome and OW/obesity, Tanner stage, gender, and HOMA-IR.

METHODS

Data were collected from 1009 children (508 males) in 10 elementary schools between April and September 2007. BMI, waist circumference, blood pressure, Tanner, lipids, insulin, and glucose were determined. Criteria analogous to ATPIII were used for metabolic syndrome in children.

RESULTS

Over 1009 children (508 males) aged 9.4 + or - 2.0 years were evaluated. One hundred and sixty-five (16.4%) were obese (>95th percentile), and 166 (16.5%) were OW (85-95th). Twenty-five (2.5%) were severely obese (BMI>99th). Most of the children (62%; 613/979) were at Tanner 1. Triglycerides, insulin, and HOMA-IR were higher (p<0.001) and HDL-C lower (p<0.001) in OW/obesity in both age groups and genders. The prevalence of metabolic syndrome was 5.8% overall, 32% in severely obese, 16.4% in OW/obese and 0.4% in normal weight children. Multiple logistic regression showed that BMI (OR 24.48; 95% CI 9.14-65.57), and HOMA-IR (OR 2.09; 95% CI 1.04-4.18) were associated with metabolic syndrome adjusted by gender and Tanner stage. Multiple linear regression also showed that BMI and HOMA-IR were independently associated with the number of metabolic syndrome components (R(2)=0.46).

CONCLUSIONS

A substantial number of OW/obese children have the metabolic syndrome. HOMA-IR and BMI were strong predictors of metabolic syndrome in children suggesting that OW/obese school children are at a higher risk for future cardiovascular disease.

Targeting sedentary time or moderate- and vigorous-intensity activity: independent relations with adiposity in a population-based sample of 10-y-old British children

BACKGROUND

It is unclear whether subcomponents of physical activity (PA) are associated with adiposity independent of time spent while sedentary.

OBJECTIVE

The objective was to examine associations between objectively measured PA and its subcomponents [ie, time spent at light-intensity PA, moderate-intensity PA (MPA), vigorous-intensity PA (VPA), and moderate-plus-vigorous-intensity PA (MVPA)], independent of sedentary time, and self-reported leisure screen time (television and electronic game use) with indexes of adiposity in a population-based sample of British children.

DESIGN

A cross-sectional study was conducted in 1862 UK children aged 9-10 y. PA and sedentary activity were measured by accelerometry, and indicators of adiposity were waist circumference, body mass index (BMI), and fat mass index calculated from bioimpedance measurements. Screen time was assessed by self-report. We examined the associations between PA subcomponents and adiposity by multilevel linear models adjusted for birth weight, maternal BMI, energy intake, and sleep duration.

RESULTS

Objectively measured sedentary time was positively associated with waist circumference (P = 0.04) and fat mass index (P = 0.05), independent of age and sex. However, this association was attenuated after adjustment for MVPA and other covariates. VPA (all P < 0.0001), combined MVPA (all P < 0.01), and total activity (counts/min) (all P < 0.001) were all inversely associated with each of the adiposity indexes, independent of sedentary time and other important covariates. Associations were weaker for MPA: P = 0.05, 0.87, and 0.1 for waist circumference, BMI, and fat mass index, respectively.

CONCLUSIONS

Time spent in VPA appears to be more strongly associated with adiposity than sedentary time. Interventions may therefore need to incorporate higher intensity-based activities to curb the growing obesity epidemic.

Sugar-Sweetened Beverage Intake Trends in US Adolescents and Their Association with Insulin Resistance-Related Parameters

The purpose of this study was to evaluate current sugar-sweetened beverage (SSB) consumption trends and their association with insulin resistance-related metabolic parameters and anthropometric measurements by performing a cross-sectional analysis of the NHANES data during the years 1988–1994 and 1999–2004. Main outcome measures included SSB consumption trends, a homeostasis model assessment of insulin resistance, blood pressure, waist circumference, body mass index, and fasting concentrations of total cholesterol, HDL-cholesterol, LDL-cholesterol, and triglycerides. Although overall SSB consumption has increased, our data suggest that this increase was primarily due to an increase in the amount of SSBs consumed by males in the high-SSB intake group alone. Multivariate linear regression analyses also showed that increased SSB consumption was independently associated with many adverse health parameters. Factors other than SSB consumption must therefore be contributing to the increasing prevalence of obesity and metabolic syndrome in the majority of US children.

Screening of metabolic syndrome in obese children: a primary care concern

OBJECTIVE

To determine the prevalence of metabolic syndrome (MS) in a primary care pediatric setting and to collect clinical and biochemical data, allowing for a prediction of its presence in a supposedly healthy population.

METHODS

Belonging to a pediatric population followed by pediatricians of the Italian National Health Service, 415 subjects with obesity as a unique selection criterion were enrolled. The entire cohort was screened for MS, which was defined as the presence of at least 2 other findings out of obesity: fasting hyperglycemia, low levels of high-density lipoproteins cholesterol, hypertriglyceridemia, and hypertension.

RESULTS

The overall prevalence of MS was 30.8%. Major findings (out of obesity) were low high-density lipoproteins cholesterol levels (46.2%), hypertension (23.6%), hypertriglyceridemia (22.2%), and fasting hyperglycemia (16.6%). Waist-to-height ratio was the only clinical parameter directly related to MS, with the same predictive power of insulin resistance.

CONCLUSIONS

Metabolic syndrome can be present in a significant percentage of "healthy" obese children, and a simple clinical parameter could identify at-risk subjects. This observation justifies the development and implementation of pediatric networks for obesity screening programs.

Genes on rat chromosomes 3, 5, 10, and 16 are linked with facets of metabolic syndrome

WOKW (Wistar Ottawa Karlsburg W) rats develop metabolic syndrome closely resembling human disorder. In crossing studies between disease-prone WOKW and disease-resistant DA (Dark Agouti) rats, several quantitative trait loci (QTLs) were mapped. To prove the in vivo relevance of QTLs, congenic DA.WOKW rats, briefly termed DA.3aW, DA.3bW, DA.5W, DA.10W, and DA.16W, were generated by transferring chromosomal regions of WOKW chromosomes 3, 5, 10, and 16 onto DA genetic background. Male (n=12) and female (n=12) rats of each congenic strain and their parental strain DA were characterized for adiposity index (AI), serum leptin, and serum insulin as well as serum cholesterol and serum triglycerides as single facets of metabolic syndrome at the age of 30 weeks. The data showed a significant higher AI for male and female DA.3aW and female DA.16W compared with DA. Serum leptin was significantly elevated in male and female DA.3aW, DA.10W, and DA.16W rats in comparison with DA. Rats of both sexes of DA.10W and female DA.16W showed significantly elevated serum insulin in comparison to DA. Female rats of all congenics had significantly higher serum cholesterol compared with DA, while males did not differ. Finally, triglycerides were only elevated in male DA.16W. The results demonstrate an involvement of WOKW chromosomes 3, 5, 10, and 16 in developing facets of the metabolic syndrome.

Relationship between insulin resistance-associated metabolic parameters and anthropometric measurements with sugar-sweetened beverage intake and physical activity levels in US adolescents: findings from the 1999-2004 National Health and Nutrition Examination Survey

OBJECTIVE

To evaluate the relationship between insulin resistance-associated metabolic parameters and anthropometric measurements with sugar-sweetened beverage intake and physical activity levels.

DESIGN

A cross-sectional analysis of the National Health and Nutrition Examination Survey data collected by the National Center for Health Statistics.

SETTING

Nationally representative samples of US adolescents participating in the National Health and Nutrition Examination Survey during the years 1999-2004.

PARTICIPANTS

A total of 6967 adolescents aged 12 to 19 years.

MAIN EXPOSURE

Sugar-sweetened beverage consumption and physical activity levels.

OUTCOME MEASURES

Glucose and insulin concentrations, a homeostasis model assessment of insulin resistance (HOMA-IR), total, high-density lipoprotein, and low-density lipoprotein cholesterol concentrations, triglyceride concentrations, systolic and diastolic blood pressure, waist circumference, and body mass index (calculated as weight in kilograms divided by height in meters squared) percentile for age and sex.

RESULTS

Multivariate linear regression analyses showed that increased sugar-sweetened beverage intake was independently associated with increased HOMA-IR, systolic blood pressure, waist circumference, and body mass index percentile for age and sex and decreased HDL cholesterol concentrations; alternatively, increased physical activity levels were independently associated with decreased HOMA-IR, low-density lipoprotein cholesterol concentrations, and triglyceride concentrations and increased high-density lipoprotein cholesterol concentrations. Furthermore, low sugar-sweetened beverage intake and high physical activity levels appear to modify each others' effects of decreasing HOMA-IR and triglyceride concentrations and increasing high-density lipoprotein cholesterol concentrations.

CONCLUSIONS

Sugar-sweetened beverage intake and physical activity levels are each independently associated with insulin resistance-associated metabolic parameters and anthropometric measurements in adolescents. Moreover, low sugar-sweetened beverage intake and high physical activity levels appear to modify each others' effects on several health-related outcome variables.

Long-term consequences of drugs on the paediatric cardiovascular system

Many pharmacological and toxicological actions of drugs in children cannot be fully predicted from adult clinical experience or from standard non-clinical toxicology studies. Numerous drugs have direct or indirect pharmacological effects on the heart and are prescribed for children of all ages. Toxicity or secondary effects may be immediate or delayed for years after drug exposure has ceased. Originally, the aim of this review was to compile information on the effect of specific drugs on the post-natal development of the cardiovascular system and to examine long-term follow-up of the use of cardio-active drugs in children. The limited database of published information caused the original question to evolve into an examination of the medical literature for three areas of information: (i) whether vulnerable developmental windows have been identified that reflect the substantial functional development that the cardiovascular system undergoes after birth; (ii) what is known about pharmacological perturbation of development; and (iii) what the likelihood is of drug exposure during childhood. We examined different scenarios for exposure including random, isolated exposure, conditions historically associated with adults, primary or secondary cardiac disease, psychiatric and neurological conditions, asthma, cancer and HIV. Except for random, isolated drug exposures, each category of possible exposure contained numerous drugs known to have either primary or secondary effects on the cardiovascular system or to influence factors associated with atherosclerosis. It is likely that a significant number of children will be prescribed drugs having either direct or indirect effects upon the immature cardiovascular system. A confounding factor is the simultaneous use of over-the-counter medications and herbal or nutraceutical preparations that a patient, parent or guardian does not mention to a prescribing physician. Metabolism is also important in assessing drug effects in children. Differences in body water : body fat ratio, age-related gastrointestinal absorption, distribution, excretion, renal function and drug metabolizing capabilities make it possible for children to have a different metabolite profile for a drug compared with adults. There is little examination of drug effects on the interdependent processes of cardiac maturation and less examination of metabolite effects. It is difficult to identify delayed toxicities in children as these adverse events may take years to manifest with many patients lost to follow-up. Clearly this is an area of study where intermediate endpoints and surrogate markers would be of great benefit. Pharmacogenomics may be useful in providing markers of increased risk or susceptibility. A perspective must be kept in balancing the possibility of a problem with the very real benefits that many children experience from the use of these pharmaceuticals.

Variations in prevalence and conduct of school food gardens in tropical and subtropical regions of north-eastern Australia

OBJECTIVES

To determine the prevalence and usage of food gardens in primary schools in three distinct climatic regions of north-eastern Australia.

DESIGN

Cross-sectional surveys combining quantitative and qualitative data collection. Two separate telephone questionnaires were developed and implemented, according to the presence or absence of a food garden within the school. Main outcome measures were answers to scaled response and open-ended questions related to factors supporting and inhibiting the establishment and sustainability of school food gardens.

SETTING

All state primary schools in three disparate regions of the north-eastern Australian state of Queensland were asked to participate in the study.

RESULTS

A total of 71% (n 128) of schools agreed to participate. Of these, thirty-seven primary schools had functioning food gardens. The variations in prevalence between regions combined with respondent views indicated climate as a major factor affecting the success of food gardens. Gardens were often used as a tool by schools to teach science, environment or social skills. Gardening activities were generally linked to curriculum studies on plants, fruit and vegetable intake, and healthy eating. The main issues for schools and teachers in establishing food gardens were the time required and the lack of personnel to coordinate garden activities. Of the schools with food gardens, 92% believed their garden had been a success.

CONCLUSIONS

The study revealed strong grass-roots support for school-based food gardens. Although climate and location were important factors associated with the presence of a functioning food garden, respondents nominated teacher involvement and sustained motivation as essential factors for successful school food gardens.

Prevalence and correlates of the metabolic syndrome in a population-based sample of European youth

BACKGROUND

Until recently, there has been no unified definition of the metabolic syndrome (MetS) in the youth. Therefore, the prevalence of MetS and its association with potential correlates are largely unknown.

OBJECTIVE

The objective was to quantify the prevalence, identify the correlates, and examine the independent associations between potential correlates with MetS.

DESIGN

A population-based cohort study was conducted in 10- and 15-y-old youth from Estonia, Denmark, and Portugal (n = 3193). MetS was defined according to the International Diabetes Federation. Correlates included maternal socioeconomic status, body mass index (BMI), hypertension, and prevalent diabetes and maternally reported child's birth weight and duration of breastfeeding. Data on sexual maturity, objectively measured physical activity, cardiorespiratory fitness, self-reported sports participation, television viewing, and regular play were collected for the children.

RESULTS

The prevalence of MetS was 0.2% and 1.4% in 10- and 15-y-olds, respectively. Cardiorespiratory fitness (standardized odds ratio: 0.33; 95% CI: 0.15, 0.75), physical activity (standardized odds ratio: 0.40; 95% CI: 0.18, 0.88), and maternal BMI (standardized odds ratio: 1.61; 95% CI: 1.11, 2.34) were all independently associated with MetS after adjustment for sex, age group, study location, birth weight, and sexual maturity. An increase in daily moderate-intensity physical activity by 10-20% was associated with a 33% lower risk of being categorized with MetS.

CONCLUSIONS

High maternal BMI and low levels of cardiorespiratory fitness and physical activity independently contribute to the MetS and may be targets for future interventions. Relatively small increases in physical activity may significantly reduce the risk of MetS in healthy children.

Sucrose-induced obesity impairs novel object recognition learning in young rats

In addition to its metabolic consequences, obesity may lead to impairments in learning and memory. To test this possibility, male Long-Evans rats were fed ground chow, or chow and either a 32% sucrose solution or hydrogenated vegetable fat (Crisco) for eight weeks. Cognitive behavior was then assessed using a novel object recognition task. To determine if there was a relationship between cognitive behavior and glucose metabolism, performance on the novel object recognition task was correlated with fasting blood glucose levels and responses on an oral glucose tolerance test. Rats fed sucrose or fat consumed more calories, gained more weight, and had larger epididymal fat pads than rats fed only chow. Additionally, fasting blood glucose levels, and the area under the glucose curve following an oral glucose tolerance test were greater in rats consuming a supplemental source of fat or sucrose than in those eating only chow. During training when rats were presented with two identical objects in an open field, time spent exploring the objects did not differ as a function of dietary conditions. However, when rats were tested 1 h later with one familiar and one novel object, rats given sucrose spent significantly less time exploring the novel object than rats eating only chow. The percent of time spent exploring the novel object was negatively correlated with fasting blood glucose levels, final body weights, and epididymal fat pad weights. It is hypothesized that the impairment in object recognition in rats eating sucrose is due, at least in part, to diet-induced alterations in glucose metabolism.

A school-based intervention to reduce overweight and inactivity in children aged 6-12 years: study design of a randomized controlled trial

BACKGROUND

Effective interventions to prevent overweight and obesity in children are urgently needed especially in inner-city neighbourhoods where prevalence of overweight and inactivity among primary school children is high. A school based intervention was developed aiming at the reduction of overweight and inactivity in these children by addressing both behavioural and environmental determinants.

METHODS/DESIGN

The main components of the intervention (Lekker Fit!) are the re-establishment of a professional physical education teacher; three (instead of two) PE classes per week; additional sport and play activities outside school hours; fitness testing; classroom education on healthy nutrition, active living and healthy lifestyle choices; and the involvement of parents. The effectiveness of the intervention is evaluated through a cluster randomized controlled trial in 20 primary schools among grades 3 through 8 (6-12 year olds). Primary outcome measures are BMI, waist circumference and fitness. Secondary outcome measures are assessed in a subgroup of grade 6-8 pupils (9-12 year olds) through classroom questionnaires and constitute of nutrition and physical activity behaviours and behavioural determinants. Multilevel regression analyses are used to study differences in outcomes between children in the intervention schools and in control schools, taking clustering of children within schools into account.

DISCUSSION

Hypotheses are that the intervention results in a lower prevalence of children being overweight and an improved mean fitness score, in comparison with a control group where the intervention is not implemented. The results of our study will contribute to the discussion on the role of physical education and physical activity in the school curriculum.

TRIAL REGISTRATION

[ISRCTN84383524].

Physical activity, cardiorespiratory fitness, and the metabolic syndrome in youth

The metabolic syndrome is defined as the coexistence of multiple cardiovascular and diabetes risk factors, the prevalence of which has increased dramatically in adult populations in the last decades. More recently, the same cluster of metabolic risk factors has also been recognized in children and adolescents. Epidemiological evidence suggests that high levels of cardiorespiratory fitness (CRF) and physical activity are associated with a favorable metabolic risk profile in adults. However, in youth the role of these factors is less clear. Therefore, the purpose of this mini-review is to examine the recent evidence between objectively measured habitual physical activity and CRF with clustered metabolic risk in youth. In general, it appears that both physical activity and CRF are separately and independently associated with metabolic risk factors in youth, possibly through different causal pathways. Further research is necessary to quantify how much physical activity is needed to prevent the metabolic syndrome and the diseases with which it is associated. Public health approaches that encourage increased physical activity and reduce sedentary behaviors may prove useful in reducing the population burden associated with metabolic risk.

Prevalence of metabolic syndrome (MS) in children and adolescents with varying degrees of obesity

OBJECTIVE

Childhood obesity is increasingly common and is associated with health problems; in particular, obesity plays a central role in the metabolic syndrome (MS). We estimated the prevalence of MS in Caucasian children and adolescents with varying degrees of obesity.

PATIENTS AND METHODS

We studied 191 obese [body mass index (BMI) > 97th percentile] children and adolescents. Obesity was stratified on the basis of a threshold BMI z-score and subjects were classified as moderately (z-score 2-2.5) or severely obese (z-score > 2.5). Seventy-six, nonobese subjects were recruited into a comparison group. Thirty-one of them were of normal weight (BMI < 75th percentile) and 45 overweight (BMI 75th-97th percentile). Patients were classified as having MS if they met three or more of the following criteria for age and sex: BMI > 97th percentile, triglyceride levels > 95th percentile, high density lipoprotein (HDL) cholesterol level < 5th percentile, systolic or diastolic blood pressure > 95th percentile and impaired glucose tolerance (blood glucose level: 7.8-11.1 mmol/l at 2 h). Insulin resistance was calculated using the homeostasis model assessment for insulin resistance (HOMA-IR) and impaired insulin sensitivity was defined as a HOMA-IR > or = 2.5 in prepubertal patients and HOMA-IR > 4 in pubertal subjects.

RESULTS

The overall prevalence of MS was 13.9% and was present in 12.0% of moderately obese and 31.1% of severely obese subjects; no overweight or normal weight subjects met the criteria for MS. The rate of the MS increased progressively with increasing BMI categories (P < 0.001). Severely obese patients had a threefold increased risk with respect to moderately obese patients.

CONCLUSIONS

The prevalence of the MS is higher in obese as opposed to nonobese subjects and increases with severity of obesity.

Childhood origins of arterial disease

PURPOSE OF REVIEW

The present article reviews the importance of classical and novel risk factors that present in childhood, track into adult life and contribute to arterial disease. The value of noninvasive techniques that can assist in characterization of preclinical atherosclerotic changes as intermediate phenotypes is also discussed.

RECENT FINDINGS

Noninvasive functional and structural techniques are now available and provide the opportunity to characterize early arterial disease long before cardiovascular complications present. By using these techniques, it has been possible to quantify the impact of conventional and novel cardiovascular risk factors seen in childhood on the development of preclinical atherosclerotic changes. Scientific interest has recently widened to include not only study of mechanisms and biomarkers of injury but also mechanisms that promote vascular repair. In this new field, characterization of endothelial progenitor cells has presented new opportunities for cardiovascular research.

SUMMARY

Atherosclerosis begins in early life. Primary prevention strategies for adult cardiovascular disease beginning in childhood have great potential as the disease process is most reversible at this stage. Several guidelines have recently been published for screening and implementation of appropriate therapeutic choices in early life.