TV Time but Not Computer Time Is Associated with Cardiometabolic Risk in Dutch Young Adults

Background

TV time and total sedentary time have been positively related to biomarkers of cardiometabolic risk in adults. We aim to examine the association of TV time and computer time separately with cardiometabolic biomarkers in young adults. Additionally, the mediating role of waist circumference (WC) is studied.

Methods and Findings

Data of 634 Dutch young adults (18–28 years; 39% male) were used. Cardiometabolic biomarkers included indicators of overweight, blood pressure, blood levels of fasting plasma insulin, cholesterol, glucose, triglycerides and a clustered cardiometabolic risk score. Linear regression analyses were used to assess the cross-sectional association of self-reported TV and computer time with cardiometabolic biomarkers, adjusting for demographic and lifestyle factors. Mediation by WC was checked using the product-of-coefficient method.TV time was significantly associated with triglycerides (B = 0.004; CI = [0.001;0.05]) and insulin (B = 0.10; CI = [0.01;0.20]). Computer time was not significantly associated with any of the cardiometabolic biomarkers. We found no evidence for WC to mediate the association of TV time or computer time with cardiometabolic biomarkers.

Conclusions

We found a significantly positive association of TV time with cardiometabolic biomarkers. In addition, we found no evidence for WC as a mediator of this association. Our findings suggest a need to distinguish between TV time and computer time within future guidelines for screen time.     

Diabetes Status and Race are Associated With Cardiovascular Risk Markers in Obese Adolescents

ObjectiveThe objective of this study was to evaluate differences in cardiovascular disease (CVD) risk markers in obese adolescents based on diabetes status and race in order to improve risk-reduction intervention strategies.MethodsThis was a retrospective, cross-sectional study of obese adolescents, age 10 to 21 years, who were evaluated at Children’s of Alabama between 2000 and 2012. Subjects were classified by glycated hemoglobin (HbA_1c) as having normoglycemia, prediabetes, or type 2 diabetes mellitus (T2DM).ResultsThere were a total of 491 African American (AA) or Caucasian American (CA) subjects. Body mass index was not different between HbA_1c and racial groups. Compared to subjects with normoglycemia or prediabetes, subjects with T2DM had higher levels of total cholesterol (TC) (178.6 ± 43.8 mg/dL vs. 161.5 ± 32.5 mg/dL vs. 162.4 ± 30.6 mg/dL; P < .0001) and low-density-lipoprotein cholesterol (107.4 ± 39.2 mg/dL vs. 97.0 ± 31.0 mg/dL vs. 97.5 ± 26.9 mg/dL; P = .0073). Compared with AA subjects, CA subjects had lower high-density-lipoprotein cholesterol (HDL-C) levels (40.4 ± 10.4 mg/dL vs. 44.3 ± 11.9 mg/dL; P = .0005) and higher non-HDL-C levels (129.6 ± 36.2 mg/dL vs. 122.5 ± 37.5 mg/dL; P = .0490). Of the characteristics studied, HbA_1c had the most significant positive association with dyslipidemia and was strongly correlated with both TC (β, 4.21; P < .0001) and non-HDL-C (β, 4.3; P < .0001).ConclusionObese adolescents with T2DM have more abnormal lipoprotein profiles than those with normoglycemia or prediabetes. Obese CA adolescents have more abnormal lipids than obese AA adolescents. HbA_1c was the characteristic most highly associated with abnormal lipoprotein profiles in our subjects. Our results show that CVD risk markers in obese adolescents vary by race and HbA_1c concentration. (Endocr Pract. 2015;21:165-173)     

Cardiometabolic Risk Profiles Associated with Chronic Complications in Overweight and Obese Type 2 Diabetes Patients in South China

Background

Type 2 diabetes is often accompanied by altered cardiometabolic risk profiles, including abdominal obesity, hypertension, and dyslipidaemia. The association of altered cardiometabolic risk profiles with chronic complications of diabetes is not well investigated.

Methods

We recruited 2954 type 2 diabetes patients with a body mass index ≥25 kg/m² who visited the diabetes clinics of 62 hospitals in 21 cities in Guangdong province of China from August 2011 to March 2012. Demographic characteristics, personal and family medical histories, and data on chronic complications of diabetes were collected. Clinical examinations and laboratory assessment were conducted.

Results

Abdominal obesity was found in 91.6% of the study population, elevated blood pressure in 78.3%; elevated serum triacylglycerols in 57.8%, and reduced serum HDL-C in 55.9%. Among the cardiometabolic risk factors, elevated blood pressure was significantly associated with almost all the chronic complications of diabetes. After adjusting for age, gender, duration of diabetes, and HbA1c, elevated blood pressure was significantly associated with diabetic retinopathy (OR 1.63, 95% CI: 1.22–2.19), diabetic nephropathy (OR 3.16, 95% CI: 2.25–4.46), cardiovascular disease (OR 2.71, 95% CI: 1.70–4.32), and stroke (OR 1.90, 95% CI: 1.15–3.12). Abdominal adiposity was significantly associated with diabetic nephropathy (OR 1.39, 95% CI: 1.11–1.74). Elevated triacylglycerols was significantly associated with diabetic retinopathy (OR 1.29, 95% CI: 1.05–1.58) and diabetic nephropathy (OR 1.30, 95% CI: 1.05–1.58). Reduced HDL-C was significantly associated with stroke (OR 1.41, 95% CI: 1.05–1.88).

Conclusions

Altered cardiometabolic risk profiles, and elevated blood pressure in particular, were significantly associated with chronic complications in overweight and obese patients with type 2 diabetes. Future studies on the prevention of chronic complications of diabetes might make lowering blood pressure a primary target.     

Light-Intensity Physical Activity and Cardiometabolic Biomarkers in US Adolescents

Background

The minimal physical activity intensity that would confer health benefits among adolescents is unknown. The purpose of this study was to examine the associations of accelerometer-derived light-intensity (split into low and high) physical activity, and moderate- to vigorous-intensity physical activity with cardiometabolic biomarkers in a large population-based sample.

Methods

The study is based on 1,731 adolescents, aged 12–19 years from the 2003/04 and 2005/06 National Health and Nutrition Examination Survey. Low light-intensity activity (100–799 counts/min), high light-intensity activity (800 counts/min to <4 METs) and moderate- to vigorous-intensity activity (≥4 METs, Freedson age-specific equation) were accelerometer-derived. Cardiometabolic biomarkers, including waist circumference, systolic blood pressure, diastolic blood pressure, HDL-cholesterol, and C-reactive protein were measured. Triglycerides, LDL- cholesterol, insulin, glucose, and homeostatic model assessments of β-cell function (HOMA-%B) and insulin sensitivity (HOMA-%S) were also measured in a fasting sub-sample (n = 807).

Results

Adjusted for confounders, each additional hour/day of low light-intensity activity was associated with 0.59 (95% CI: 1.18–0.01) mmHG lower diastolic blood pressure. Each additional hour/day of high light-intensity activity was associated with 1.67 (2.94–0.39) mmHG lower diastolic blood pressure and 0.04 (0.001–0.07) mmol/L higher HDL-cholesterol. Each additional hour/day of moderate- to vigorous-intensity activity was associated with 3.54 (5.73–1.35) mmHG lower systolic blood pressure, 5.49 (1.11–9.77)% lower waist circumference, 25.87 (6.08–49.34)% lower insulin, and 16.18 (4.92–28.53)% higher HOMA-%S.

Conclusions

Time spent in low light-intensity physical activity and high light-intensity physical activity had some favorable associations with biomarkers. Consistent with current physical activity recommendations for adolescents, moderate- to vigorous-intensity activity had favorable associations with many cardiometabolic biomarkers. While increasing MVPA should still be a public health priority, further studies are needed to identify dose-response relationships for light-intensity activity thresholds to inform future recommendations and interventions for adolescents.     

Intraperitoneal Fat and Insulin Resistance in Obese Adolescents

Obesity is epidemic among adolescents in the United States. We sought to analyze the anthropometric measures of adiposity and fasting indices of insulin resistance, including insulin‐like growth factor–binding protein‐1 (IGFBP‐1), and to provide a clinical estimate of intraperitoneal (IP) fat in obese adolescents (BMI ≥95th percentile), between ages 13 and 17 years. Subjects had baseline testing to determine eligibility for a subsequent randomized, placebo‐controlled trial of metformin XR therapy. Anthropometry and dual‐energy X‐ray absorptiometry (DXA) were used to quantify total body fat while abdominal computed tomography (CT) was used to measure IP (CT‐IP) and subcutaneous (CT‐SQ) fat. Using anthropometry and fasting laboratory data, we constructed regression models for both CT‐IP and CT‐SQ. A total of 92 subjects, 33 males, were evaluated. Of the 92 subjects, 19 were black. Fasting insulin concentrations were highly associated with other measures of insulin resistance. Median percent body fat across all subjects, as measured by DXA, was 41%. Using CT measures, 67% of abdominal cross‐sectional area was fat, 14% of which was IP fat. In multiple regression analysis, waist circumference (WC) and BMI, jointly and independently, were strongly associated with both CT‐IP and CT‐SQ fat. BMI and WC explained 62% of variance of CT‐SQ fat, but only 26% of variance of CT‐IP fat. Adding triglyceride:high‐density lipoprotein (TG:HDL) ratio and IGFBP‐1 (among nonblacks) to the regression model increased the explained variance for estimating CT‐IP fat to 45%. When evaluating the metabolic morbidity of an obese adolescent, a model using fasting IGFBP‐1, TG:HDL, BMI, and WC may be worthwhile as an estimate of IP fat.     

Total and Regional Fat and Serum Cardiovascular Disease Risk Factors in Lean and Obese Children and Adolescents

Objective: This study was conducted to evaluate the association of total and central adiposity with serum cardiovascular disease (CVD) risk factors in lean and obese Portuguese children and adolescents. Research Methods and Procedures: A total of 87 girls (13.2 ± 1.6 years old, 29.9 ± 6.4% body fat [mean ± SD]) and 72 boys (13.2 ± 1.6 years old, 20.8 ± 9.9% body fat) volunteered for the study. Whole‐body composition and fat distribution, from DXA and anthropometry, and serum lipids, lipoproteins, and apolipoproteins were evaluated. Results: The sum of three trunk skinfolds (STS) was highly correlated with total trunk fat mass measured by DXA (p < 0.001). Body mass index, DXA‐measured percentage of body fat, trunk fat mass, STS, and the waist‐to‐height ratio were generally found to be associated with triacylglycerol, the ratio of total cholesterol (TC) to high density lipoprotein‐cholesterol (HDL‐C), low density lipoprotein‐cholesterol (LDL‐C), and apolipoprotein B levels, (significant age‐adjusted r between 0.16 and 0.27, p < 0.05). Body mass index, STS, and the waist circumference were also associated with HDL‐C (p < 0.05), whereas no body composition variable significantly correlated with TC or apolipoproteins A‐I. The STS was significantly correlated with HDL‐C (p < 0.01), TC/HDL‐C (p < 0.05), and apolipoproteins A‐I (p < 0.05) independently of whole‐body fatness. Obese subjects (n = 73) had higher TC, LDL‐C, TC/HDL‐C, and apolipoprotein B than did non‐obese subjects (n = 86), and significant associations between central adiposity and some lipid variables (triacylglycerol and HDL‐C) were found in obese children and adolescents that were not present in leaner individuals. Discussion: DXA‐ and anthropometry‐based whole‐body and central fat measures are associated with serum CVD risk factors in Portuguese boys and girls. Obese children and adolescents have a poorer lipid profile than do their leaner counterparts. Trunk skinfolds, which are easy to obtain even in large samples, predict CVD risk factors to the same extent as DXA‐based variables, in some cases, independently of total fatness.     

Neighborhood Street Scale Elements,Sedentary Time and Cardiometabolic Risk Factors in Inactive Ethnic Minority Women

Background

Cardiometabolic risk factors such as obesity, excess percent body fat, high blood pressure, elevated resting heart rate and sedentary behavior have increased in recent decades due to changes in the environment and lifestyle. Neighborhood micro-environmental, street scale elements may contribute to health above and beyond individual characteristics of residents.

Purpose

To investigate the relationship between neighborhood street scale elements and cardiometabolic risk factors among inactive ethnic minority women.

Method

Women (N = 410) completed measures of BMI, percent body fat, blood pressure, resting heart rate, sedentary behavior and demographics. Trained field assessors completed the Pedestrian Environment Data Scan in participants’ neighborhoods. Data were collected from 2006–2008. Multiple regression models were conducted in 2011 to estimate the effect of environmental factors on cardiometabolic risk factors.

Results

Adjusted regression models found an inverse association between sidewalk buffers and blood pressure, between traffic control devices and resting heart rate, and a positive association between presence of pedestrian crossing aids and BMI (ps<.05). Neighborhood attractiveness and safety for walking and cycling were related to more time spent in a motor vehicle (ps<.05).

Conclusions

Findings suggest complex relationships among micro-environmental, street scale elements that may confer important cardiometabolic benefits and risks for residents. Living in the most attractive and safe neighborhoods for physical activity may be associated with longer times spent sitting in the car.     

Cognitive Change in Obese Adolescents Losing Weight

Objectives: To investigate how obese adolescents think about themselves in terms of exercise, eating, and appearance and whether these cognitions change over the course of a residential weight loss camp. Research Methods and Procedures: Obese adolescents [N = 61; age, 14.1 (±0.2) years; BMI, 33.9 (±0.7) kg/m²] completed assessments of body weight and height and self‐esteem and a sentence‐completion test eliciting thoughts and beliefs about exercise, eating, and appearance at the start and end of the camp (mean stay, 26 days). They were compared with a single assessment of 20 normal‐weight adolescents [age, 15.4 (±0.2) years; BMI, 21.8 (±0.5) kg/m²]. Results: The obese adolescents lost 5.7 kg and reduced their BMI SD score by 0.25. Camp residence was associated with a significant reduction in the number of negative automatic thoughts and an increase in positive thoughts, especially related to exercise and appearance. There was no change in conditional beliefs, either functional or dysfunctional. Including BMI SD score change as a covariate took away all the main and interaction effects of time, showing that cognitive change was largely accounted for by the reduction in weight. Despite this improvement, campers remained cognitively more negative and dysfunctional than the normal‐weight comparison adolescents. Discussion: Obese adolescents not only lost weight, but they improved their self‐representation, specifically in terms of automatic thoughts about exercise and appearance. Although these are short‐term cognitive changes, they reflect positively on the camp experience and show the value of psychological improvement in assessing obesity‐treatment outcomes.     

Accelerometer-Derived Sedentary and Physical Activity Time in Overweight/Obese Adults with Type 2 Diabetes: Cross-Sectional Associations with Cardiometabolic Biomarkers

Objective

To examine the associations of sedentary time and physical activity with biomarkers of cardiometabolic health, including the potential collective impact of shifting mean time use from less- to more-active behaviours (cross-sectionally, using isotemporal substitution), in adults with type 2 diabetes.

Methods

Participants with overweight/obese body mass index (BMI; ≥25 kg/m²) (n = 279; 158 men, mean [SD] age = 58.2 [8.6] years) wore Actigraph GT1M accelerometers (waking hours; seven days) to assess moderate- to vigorous-intensity physical activity (MVPA), light-intensity activity, and sedentary time (segregated into non-prolonged [accumulated in bouts <30min] and prolonged [accumulated in bouts ≥30 min]). Cross-sectional associations with waist circumference, BMI, fasting blood (HbA_1c, glucose, triacylglycerols, high-density lipoprotein cholesterol), and blood pressure of these activity variables (30 min/day increments) were examined adjusted for confounders and wear then, if significant, examined using isotemporal substitution modelling.

Results

Waist circumference and BMI were significantly (p<0.05) associated with more prolonged sedentary time and less light-intensity activity. Light intensity activity was also significantly associated with lower fasting plasma glucose (relative rate: 0.98, 95% CI: 0.97, 1.00; p<0.05). No biomarker was significantly associated with non-prolonged sedentary time or MVPA. Lower mean prolonged sedentary time (−30 min/day) with higher mean light intensity time (+30 min/day) was significantly associated with lower waist circumference (β = −0.77, 95% CI: −1.33, −0.22 cm). Lower mean prolonged sedentary time (−30 min/day) with either 30 min/day higher mean non-prolonged sedentary time (β = −0.35, 95%CI: −0.70, −0.01 kg/m²) or light-intensity time (β = −0.36, −0.61, −0.11 kg/m²) was associated with significantly lower average BMI.

Conclusions

Significantly improved mean levels of waist circumference and BMI were observed when shifting time from prolonged sedentary to non-prolonged sedentary or light-intensity activity (cross-sectionally). Lifestyle interventions in overweight/obese adults with type 2 diabetes might consider targeting shifts in these non-MVPA activities to more rigorously evaluate their potential cardiometabolic benefit in this population.     

Fasting Plasma Glucose (FPG) and the Risk of Impaired Glucose Tolerance in Obese Children and Adolescents

A timely diagnosis of impaired glucose tolerance (IGT) is desirable in obesity. The oral glucose tolerance test (OGTT), the gold standard to diagnose this condition, may not be realistically performed in all patients due to discomfort, labor, and cost. The aim of this study was to assess whether one or more biochemical indexes measured in fasting conditions could be used to identify obese children at risk of IGT. A cohort of 563 white obese children and adolescents (M/F: 315/248; aged 4–17 years) was recruited and underwent anthropometric evaluation and OGTT. Anthropometric parameters, fasting plasma glucose (FPG), fasting serum insulin (FSI), and homeostasis model assessment of insulin resistance (HOMA_IR) were tested in pursuit of a possible threshold to be used as a predictor of IGT. Thirty‐seven children (6.9%) had IGT and one child (0.1%) had type 2 diabetes (T2D). FPG, FSI, and HOMA_IR were all significantly higher in children with IGT than in children without IGT. Receiver‐operating characteristic (ROC) curve analyses run for gender and puberty‐adjusted FPG, FSI, and HOMA_IR were all significant: area under the curve (95% confidence interval) equaled 0.68 (0.59–0.76), 0.66 (0.56–0.76), and 0.68 (0.59–0.78), respectively. The three parameters did not show significantly different sensitivity/specificity in the pooled population or in the gender/puberty subgroups. Thresholds varied among gender/puberty subgroups for FSI and HOMA_IR, but not for FPG, which showed a fixed threshold of 86 mg/dl. A gender/puberty independent cutoff of FPG may be considered a screening tool to narrow clinical indication to OGTT in obese white children and adolescents.     

Pathophysiologic Mechanisms Linking Adipose Tissue and Cardiometabolic Risk

ObjectiveTo describe the contribution of adipocytes and adipose tissue to increased cardiometabolic risk as well as the mechanisms by which adipose tissue and obesity contribute to dysglycemia, dyslipidemia, hypertension, and a prothrombotic, inflammatory state favoring atherogenesis.MethodsA review was undertaken of the relevant available reports, compiled by means of a search(PubMed) of the English-language literature published between 1994 and 2010.ResultsCoronary risk factors cause susceptibility to development of atherosclerosis. Traditional coronary risk factors are obesity, smoking, hypertension, diabetes, elevated serum cholesterol levels, male sex, advancing age, and a family history of early coronary events. The currently preferred term of cardiometabolic risk encompasses both the traditional coronary risk factors and the additional contributing factors of insulin resistance, atherogenic dyslipidemia, physical inactivity, unhealthful eating, inflammation, and hypercoagulation. The accumulation of adipose tissue (adiposity) and dysfunctional adipose tissue (adiposopathy) contribute to most, if not all, of the cardiometabolic risk factors. Adipose tissue promotes atherosclerosis through several different pathologic mechanisms, which are reviewed in this report. The treatment of obesity should focus on reducing fat mass and minimizing adipocyte dysfunction.ConclusionAdipose tissue contributes to the development of insulin resistance, hyperglycemia, atherogenic dyslipidemia, and arterial hypertension and favors a prothrombotic and proinflammatory state. Adipose tissue dysfunction increases cardiometabolic risk through a variety of mechanisms. (Endocr Pract. 2010;16:692-698)     

Dietary Intervention Causes Redistribution of Zinc in Obese Adolescents

Obese people tend to have low zinc circulation levels; this is not always related to zinc intake but can reflect the distribution of zinc in relation to the proportion of body fat and factors related to the inflammatory processes that cause obesity. The purpose of this study was to assess zinc distribution in 15 obese adolescent girls before and after a nutritional orientation program. Participants ranged from 14 to 18 years old (postpubescent) and had a body fat percent (BF%) of >35 %. Zinc nutritional status and other zinc-dependent parameters, such as superoxide dismutase (SOD) and insulin levels, were assessed by biochemical analysis of plasma and erythrocytes, salivary sediment, and urine. Samples were collected before and after 4 months of dietary intervention. Dual energy X-ray absorptiometry (DXA) was used to verify BF% both at the beginning and at the end of the study. Food consumption was assessed in ten individual food questionnaires throughout the study; food groups were separated on the questionnaires in the same way as suggested by some authors to develop the Healthy Eating Index (HEI) but with the addition of zinc. After 4 months of nutritional orientation, 78 % of the participants showed a decrease in BF%. Intraerythrocytic zinc increased over the study period, while salivary sediment zinc, SOD, insulin, and Zn urinary24 h/creatinine all decreased (p?<?0.05). There was no difference in zinc intake throughout the study but participants did increase their consumption of fruits, dairy, and meats during the study (p?<?0.05). There were inverse and statistically significant correlations between the increased levels of intraerythrocytic zinc and decreased levels of SOD. There was also a statistically significant correlation between BF% and Zn urinary 24h/creatinine, and SOD. All these parameters were diminished at the end of the study. The dietary intervention for obese adolescent girls is effective with decrease of BF that led to the redistribution of zinc in the body as shown by the changes in erythrocytes, plasma, salivary, urine zinc, as well as the complementary parameters of insulin and SOD. These changes were not affected by zinc intake.     

Prevalence of Elevated Thyroid-Stimulating Hormone Levels in Obese Children and Adolescents

ObjectiveTo determine the prevalence of elevated thyroid-stimulating hormone (TSH) levels in obese children and adolescents referred to pediatric endocrinology clinics.MethodsWe undertook a retrospective review of medical records of 191 obese and 125 nonobese children (younger than 18 years old). Data about age, sex, body mass index, TSH, thyroid functions, thyroid antibodies, thyroid size, and medications were collected.ResultsSix obese patients had Hashimoto disease and TSH values from 0.73 to 12.73 mIU/L; they were excluded from the study analyses. Of the remaining 185 obese subjects, 20 (10.8%) had TSH levels > 4 mIU/L, but no control subject measurement exceeded this TSH value. The highest TSH concentration in an obese study subject was 7.51 mIU/L. When obese children with TSH levels > 4 mIU/L were classified in a third group, the mean TSH in the rest of the obese children was comparable with that in the control group (1.98 ± 0.84 [SD] and 1.95 ± 0.80 mIU/L, respectively; post hoc analysis of variance, P = .945). Obese subjects with increased TSH values had a mean body mass index similar to that for obese subjects with normal TSH levels (34.98 ± 6.12 [SD] and 34.29 ± 7.84 kg/m², respectively).ConclusionMild elevation of TSH values in the absence of autoimmune thyroid disease is not uncommon in some obese children and adolescents. This is the second study in the United States to report this observation. Our study did not identify any special characteristics of obese subjects with TSH elevation in comparison with obese children with normal TSH levels and the control group. Current medical knowledge does not support routine screening for thyroid dysfunction in obese children. (Endocr Pract. 2010;16:187-190)     

Relative Age Effects in Dutch Adolescents: Concurrent and Prospective Analyses

The literature on relative age position effects is rather inconsistent. In this study we examined intra-classroom age position (or relative age) effects on Dutch adolescents’ school progress and performance (as rated by teachers), physical development, temperamental development (fear and frustration), and depressive symptoms, all adjusted for age at the time of measurement. Data were derived from three waves of Tracking Adolescents'' Individuals Lives Survey (TRAILS) of 2230 Dutch adolescents (baseline mean age 11.1, SD = 0.6, 51% girls). Albeit relative age predicted school progress (grade retention ORs = 0.83 for each month, skipped grade OR = 1.47, both p<.001), our key observation is the absence of substantial developmental differences as a result of relative age position in Dutch adolescents with a normative school trajectory, in contrast to most literature. For adolescents who had repeated a grade inverse relative age effects were observed, in terms of physical development and school performance, as well as on depressive symptoms, favoring the relatively young. Cross-cultural differences in relative age effect may be partly explained by the decision threshold for grade retention.     

Intra-erythrocyte Magnesium Is Associated with Gamma-Glutamyl Transferase in Obese Children and Adolescents

This study aims at determining the association between markers of hepatic injury and serum, urinary, and intra-erythrocyte magnesium concentrations and dietary magnesium intake in obese children and adolescents. In a case–control study, 42 obese children and adolescents (8–18 years) and 42 sex- and puberty-matched controls were studied. Serum, urinary, and intra-erythrocyte magnesium levels, indices of insulin sensitivity, and liver enzymes were measured. Dietary magnesium intake was assessed using a food frequency questionnaire. Obese children and adolescents exhibited insulin resistance as determined by a higher fasting insulin and the HOMA-IR (p < 0.001) and lower QUICKI indices (p = 0.001); in addition these subjects had significantly higher intra-erythrocyte magnesium (IEM) concentrations, than non-obese ones (3.99 ± 1.05 vs. 3.35 ± 1.26 mg/dL of packed cell; p = 0.015). Among liver enzymes, only gamma-glutamyl transferase (GGT) was significantly higher in obese than in non-obese subjects (22.7 ± 9.4 vs. 17.1 ± 7.9 U/l; p = 0.002). A positive association was found between GGT and IEM in both groups; however in multivariate analysis, in obese subjects, only GGT (p = 0.026) and, in non-obese subjects, only age (p = 0.006) remained as significant predictors of IEM. In conclusion, increased IEM concentration was seen in insulin-resistant obese children and adolescents; furthermore, serum GGT was associated with IEM, independently of body mass index and HOMA-IR.     

Increased Health Risk in Subjects with High Self-Reported Seasonality

Background

Seasonal variations in mood and behaviour, termed seasonality, are commonly reported in the general population. As a part of a large cross-sectional health survey in Hordaland, Norway, we investigated the relationship between seasonality, objective health measurements and health behaviours.

Methodology/Principal Findings

A total of 11,545 subjects between 40–44 years old participated, completing the Global Seasonality Score, measuring seasonality. Waist/hip circumference, BMI and blood pressure were measured, and blood samples were analyzed for total cholesterol, HDL cholesterol, triglycerides and glucose. Subjects also completed a questionnaire on miscellaneous health behaviours (exercise, smoking, alcohol consumption). Hierarchical linear regression analyses were used to investigate associations between seasonality and objective health measurements, while binary logistic regression was used for analysing associations between seasonality and health behaviours. Analyses were adjusted for sociodemographic factors, month of questionnaire completion and sleep duration. Seasonality was positively associated with high waist-hip-ratio, BMI, triglyceride levels, and in men high total cholesterol. Seasonality was negatively associated with HDL cholesterol. In women seasonality was negatively associated with prevalence of exercise and positively associated with daily cigarette smoking.

Conclusions/Significance

High seasonality was associated with objective health risk factors and in women also with health behaviours associated with an increased risk for cardiovascular disease.     

Muscle Carnosine Is Associated with Cardiometabolic Risk Factors in Humans

BackgroundCarnosine is a naturally present dipeptide abundant in skeletal muscle and an over-the counter food additive. Animal data suggest a role of carnosine supplementation in the prevention and treatment of obesity, insulin resistance, type 2 diabetes and cardiovascular disease but only limited human data exists.ConclusionOur data shows that higher carnosine content in human skeletal muscle is positively associated with insulin resistance and fasting metabolic preference for glucose. Moreover, it is negatively associated with HDL-cholesterol and basal energy expenditure. Intervention studies targeting insulin resistance, metabolic and cardiovascular disease risk factors are necessary to evaluate its putative role in the prevention and management of type 2 diabetes and cardiovascular disease.     

Structural and Compositional Changes in Erythrocyte Membrane of Obese Compared to Normal-Weight Adolescents

Unhealthy dietary habits are key determinants of obesity in adolescents. Assuming that dietary fat profile influences membrane lipid composition, the aim of this study was to analyze structural changes in the erythrocyte membrane of obese compared to normal-weight adolescents. The study was conducted in a group of 11 obese and 11 normal-weight adolescent subjects. The lipid profile, lipid peroxidation and acetylcholinesterase enzyme (AChE) activity were analyzed by conventional methods. The structural properties of reconstituted erythrocyte membrane were characterized by X-ray diffraction. Erythrocyte membrane from obese adolescents had a lipid profile characterized by a higher cholesterol/phospholipid ratio, an increase in saturated fatty acid and a decrease in monounsaturated and n-6 polyunsaturated fatty acid concentrations. Differences in lipid content were associated with changes in the structural properties of reconstituted membranes and the oxidative damage of erythrocyte membrane. The lower oxidative level shown in the obese group (0.15 ± 0.04 vs. 0.20 ± 0.06 nmol/mg for conjugated diene concentrations and 2.43 ± 0.25 vs. 2.83 ± 0.31 nmol/mg protein for malondialdehyde levels) was related to a lower unsaturation index. These changes in membrane structural properties were accompanied by a lower AChE activity (1.64 ± 0.13 vs. 1.91 ± 0.24 nmol AChE/[min mg protein]) in the obese group. The consequences of unhealthy dietary habits in adolescents are reflected in the membrane structural properties and may influence membrane-associated protein activities and functions.     

Associations of Sedentary Behavior,Sedentary Bouts and Breaks in Sedentary Time with Cardiometabolic Risk in Children with a Family History of Obesity

Background

Although reports in adults suggest that breaks in sedentary time are associated with reduced cardiometabolic risk, these findings have yet to be replicated in children.

Purpose

To investigate whether objectively measured sedentary behavior, sedentary bouts or breaks in sedentary time are independently associated with cardiometabolic risk in a cohort of Canadian children aged 8–11 years with a family history of obesity.

Methods

Data from 286 boys and 236 girls living in Quebec, Canada, with at least one biological parent with obesity (QUALITY cohort) were collected from 2005–2008, and analyzed in 2013. Sedentary behavior, light and moderate-to-vigorous physical activity were measured over 7 days using accelerometry. Leisure time computer/video game use and TV viewing over the past 7 days were self-reported. Outcomes included waist circumference, body mass index Z-score, fasting insulin, fasting glucose, triglycerides, HDL-cholesterol, C-reactive protein and a continuous cardiometabolic risk score.

Results

After adjustment for confounders, breaks in sedentary time and the number of sedentary bouts lasting 1–4 minutes were associated with reduced cardiometabolic risk score and lower BMI Z-score in both sexes (all p<0.05). The number of sedentary bouts lasting 5–9 minutes was negatively associated with waist circumference in girls only, while the number of bouts lasting 10–14 minutes was positively associated with fasting glucose in girls, and with BMI Z-score in boys (all p<0.05). Leisure time computer/video game use was associated with increased cardiometabolic risk score and waist circumference in boys, while TV viewing was associated with increased cardiometabolic risk, waist circumference, and BMI Z-score in girls (all p<0.05).

Conclusions

These results suggest that frequent interruptions in sedentary time are associated with a favourable cardiometabolic risk profile and highlight the deleterious relationship between screen time and cardiometabolic risk among children with a family history of obesity.