Is food insecurity related to overweight and obesity in children and adolescents? A summary of studies, 1995–2009

In the USA, several nutrition‐related issues confront the normal growth, maturation and development of children and adolescents including obesity and food insecurity. The purpose of this paper is to provide a review of the concept of food insecurity and a summary of studies that have examined the association between food insecurity and overweight/obesity in children and adolescents. Besides the initial case report, we review 21 studies (16 cross‐sectional and five prospective studies) that have been published on this topic as of December 2009. As there is limited literature in this area, we review studies that sample children and adolescents in the USA. The results are mixed with positive, negative and null associations. The reasons for the mixed results are difficult to disentangle. Among earlier studies, small samples hampered definitive conclusions. More recent studies with larger samples have overcome these limitations and tend to find no associations between these constructs. Nonetheless, all of the studies to date have shown that food insecurity and overweight co‐exist – that is, even though there may not be statistically significant differences in overweight between food‐insecure and food‐secure children, the prevalence of overweight remains relatively high in food‐insecure children.     

Salt intake is related to soft drink consumption in children and adolescents: a link to obesity?

Dietary salt is a major determinant of fluid intake in adults; however, little is known about this relationship in children. Sugar-sweetened soft drink consumption is related to childhood obesity, but it is unclear whether there is a link between salt and sugar-sweetened soft drink consumption. We analyzed the data of a cross-sectional study, the National Diet and Nutrition Survey for young people in Great Britain. Salt intake and fluid intake were assessed in 1688 participants aged 4 to 18 years, using a 7-day dietary record. There was a significant association between salt intake and total fluid, as well as sugar-sweetened soft drink consumption (P<0.001), after adjusting for potential confounding factors. A difference of 1 g/d in salt intake was associated with a difference of 100 and 27 g/d in total fluid and sugar-sweetened soft drink consumption, respectively. These results, in conjunction with other evidence, particularly that from experimental studies where only salt intake was changed, demonstrate that salt is a major determinant of fluid and sugar-sweetened soft drink consumption during childhood. If salt intake in children in the United Kingdom was reduced by half (mean decrease: 3 g/d), there would be an average reduction of approximately 2.3 sugar-sweetened soft drinks per week per child. A reduction in salt intake could, therefore, play a role in helping to reduce childhood obesity through its effect on sugar-sweetened soft drink consumption. This would have a beneficial effect on preventing cardiovascular disease independent of and additive to the effect of salt reduction on blood pressure.     

Is dietary intake able to explain differences in body fatness in children and adolescents?

Obesity is the result of an imbalance between energy intake and energy expenditure. Controversial information exists about what are the strongest energy balance aspects influencing body fatness. This article is focused on food consumption facts that could be related to the risk of being obese in children and adolescents. It reviews whether energy intake, macronutrient composition of diet, eating patterns or other dietary intake factors are able to explain differences in body composition when obesity has been already developed or even in subjects at risk to become obese. There is not enough evidence to clarify the importance of diet on overweight children and adolescents, and conclusions derived are somewhat controversial. Cross-sectional and longitudinal studies do not show clear relationships between energy intake or food composition and body fatness. To find relations between dietary factors and childhood obesity perhaps eating patterns or different types of foods must be considered: meal patterns and meal frequency, snacking and beverage consumption, fast food intake, portion sizes, etc. There is no clear association between different aspects of dietary intake and the development of obesity in children and adolescents. Longitudinal and experimental studies are needed in the future.     

Is overweight/obesity associated with short sleep duration in older women?

BACKGROUND AND AIM: No study to date has documented the association between short sleep duration and the risk for obesity in older people. Therefore, the aim of this study was to examine cross-sectional associations between short sleep duration and variations in body fat indices in older women. METHODS: Anthropometric and body composition measurements, resting energy expenditure, daily energy expenditure, daily energy intake, plasma lipid-lipoprotein profile, and self-reported sleep duration were determined in a sample of 90 women of 50 years and above. RESULTS: The odds ratios for overweight/obesity were comparable in subjects reporting <7 hours and >or=7 hours of sleep per day, with or without adjustment for age, daily energy expenditure and daily energy intake. The results did not permit to observe any significant difference between the two sleeper groups for all the variables investigated. The correlations between sleep duration and adiposity indices were also non significant. CONCLUSIONS: Short sleep duration does not predict an increased risk of being overweight/obese in older women. This observation, together with our previously reported results in younger subjects, suggests that the sleep-body fat relationship progressively becomes less detectable with increasing in age.     

Is the Canadian childhood obesity epidemic related to physical inactivity?

OBJECTIVE: This study examined the relation among children's physical activity, sedentary behaviours, and body mass index (BMI), while controlling for sex, family structure, and socioeconomic status. DESIGN: Epidemiological study examining the relations among physical activity participation, sedentary behaviour (video game use and television (TV)/video watching), and BMI on a nationally representative sample of Canadian children. SUBJECTS: A representative sample of Canadian children aged 7-11 (N=7216) from the 1994 National Longitudinal Survey of Children and Youth was used in the analysis. MEASUREMENTS: Physical activity and sport participation, sedentary behaviour (video game use and TV/video watching), and BMI measured by parental report. RESULTS: Both organized and unorganized sport and physical activity are negatively associated with being overweight (10-24% reduced risk) or obese (23-43% reduced risk), while TV watching and video game use are risk factors for being overweight (17-44% increased risk) or obese (10-61% increased risk). Physical activity and sedentary behaviour partially account for the association of high socioeconomic status and two-parent family structure with the likelihood of being overweight or obese. CONCLUSION: This study provides evidence supporting the link between physical inactivity and obesity of Canadian children.     

Defining overweight and obesity in pre‐school children: IOTF reference or WHO standard?

Two international datasets are used to define overweight and obesity in pre‐school children: the International Obesity Task Force (IOTF) reference and the WHO standard. This study compares the performance of the two datasets in defining overweight and obesity in 24–60 months old children. This was done by plotting the IOTF cut‐offs against WHO curves and by comparing the prevalence of overweight and obesity, as defined by the IOTF reference and by the WHO standard, using 2001 data from the Czech Republic. The IOTF cut‐off for overweight in 24–60 months old children goes from 1.7 to 1.1 z‐scores on the WHO chart, and for obesity it shifts with age from 2.7 to 2.2 z‐scores. As a consequence, at 5 years of age the prevalence of overweight in Czech girls is 3.4% using the WHO and 15.3% using the IOTF definition. These discrepancies are due to the choice of cut‐offs and to the different criteria used to select the sample for the IOTF reference and the WHO standard. Research is urgently needed to identify, for the WHO standard, BMI cut‐offs associated with an increased risk of overweight and obesity, and associated health outcomes later in life.     

Sleep-disordered breathing: a new risk factor of suspected fatty liver disease in overweight children and adolescents?

Introduction  The aim of this retrospective study was to investigate if sleep-disordered breathing (SDB) was an independent predictor of suspected fatty liver disease in a clinical sample of overweight children and adolescents. Materials and methods  Consecutive overweight and obese children attending a pediatric obesity clinic underwent polysomnography, fasting blood sample, and abdominal ultrasound. Results and discussion  The respiratory disturbance index, percentage of total sleep time with SO2 < 90%, and SaO2nadir were associated with higher alanine amino-transferases (ALT) independent of abdominal obesity. Multiple logistic regression selected waist circumference (odds ratio = 1.05; p = 0.05) and SaO2nadir (odds ratio = 0.87; p = 0.03) as predictors of suggestive fatty liver disease, defined as ALT > 40 U/L and/or hyperechoic liver on abdominal ultrasound. This study supports the association between the severity of SDB and suspected fatty liver disease in a clinical sample of overweight children and adolescents. We recommend more research on the influence of SDB on the development of fatty liver disease and on the effect of treating sleep apnea on liver function parameters.     

The microbiome and obesity: Is obesity linked to our gut flora?

The human gut is a lush microbial ecosystem containing about 100 trillion microorganisms, whose collective genome, the microbiome, contains 100-fold more genes than the entire human genome. The symbiosis of our extended genome plays a role in host homeostasis and energy extraction from diet. In this article, we summarize some of the studies that have advanced the understanding of the microbiome and its effects on metabolism, obesity, and health. Metagenomic studies demonstrated that certain mixes of gut microbiota may protect or predispose the host to obesity. Furthermore, microbiota transplantation studies in germ-free murine models showed that the efficient energy extraction traits of obese-type gut flora are transmissible. The proposed methods by which the microbiome may contribute to obesity include increasing dietary energy harvest, promoting fat deposition, and triggering systemic inflammation. Future treatments for obesity may involve modulation of gut microbiota using probiotics or prebiotics.     

Associations between central obesity and asthma in children and adolescents: a case–control study

Introduction: Evidence supports a significant yet weak association between high-body weight and asthma in children. However, most studies investigating the obesity–asthma link use Body Mass Index (BMI) to evaluate body fatness. The relationship between body fat distribution and asthma remains largely unknown, especially in children. This pediatric case–control investigation examined associations between central obesity/high-body weight and asthma diagnosis. Methods: Five-hundred and fourteen children (217 physician diagnosed asthma cases and 297 healthy controls) of 5–11 years were recruited. Height, weight and waist circumference were measured. Asthma symptoms, past medical history, personal lifestyle, socioeconomic status, diet and physical activity history were also collected. Results: A higher proportion of children with asthma were centrally obese [(≥90th waist percentile) 15.2 vs. 9.4%, p<0.0001; (≥90th waist-to-height ratio percentile) 39.6 vs. 24.2%, p<0.0001)]. Regression analyses revealed that centrally obese children were more likely to have asthma (high-waist circumference (OR?=?1.99, 95% CI: 1.07-3.68) and high-waist circumference to height ratio (OR?=?2.24, 95% CI: 1.47-3.40), following adjustment for various confounders. Overweight/obese participants (BMI defined) were more likely to be asthmatic [odds ratio (OR)?=?1.52, 95% confidence interval (CI): 1.03-2.70)] when compared to controls. Conclusions: Presence of central obesity and high-body weight (at least overweight) as assessed by waist circumference, waist-to-height ratio, and BMI are associated with asthma diagnosis. More studies are needed, especially in children and adolescents, to confirm these findings and better understand how body fat distribution impacts the obesity–asthma relationship.     

Is plasma 25(OH) D related to adipokines, inflammatory cytokines and insulin resistance in both a healthy and morbidly obese population?

To analyse in a cohort of healthy subjects and in a group of morbidly obese patients, we studied the association amongst 25(OH) D and plasma concentrations of adipocytokines, inflammatory cytokines and insulin resistance. We also aimed to determine whether vitamin D-deficient patients showed a greater inflammatory profile. In the observational study that the authors conducted, plasma concentrations of 25(OH) D, leptin, resistin, adiponectin and interleukine-18 were determined in 134 healthy men and 127 women. In the population consisting of 44 patients with morbid obesity, plasma concentrations of 25(OH) D, leptin, resistin, adiponectin, interleukine-18, soluble tumor necrosis factor receptors 1 and 2 and C-reactive protein were analysed. In the healthy population, plasma 25(OH) D showed a negative correlation with body mass index, body fat, waist, hip circumference and with leptin. However, no significant associations were found amongst 25(OH) D and plasma concentrations of resistin, adiponectin or interleukine-18. Patients with vitamin D deficiency showed higher body mass index, fat mass percentage and higher leptin concentrations compared with subjects with normal 25(OH) D concentrations. In the morbidly obese subjects, 25(OH) D did not correlate with leptin, resistin, adiponectin, interleukine-18, soluble tumor necrosis factor receptors 1 and 2 or with C-reactive protein. In patients with morbid obesity, no differences were found in adipokines and inflammatory cytokines concentrations regarding 25(OH) D status. No associations were found either between 25(OH) D and plasma glucose and insulin resistance or with lipid profile. Plasma 25(OH) D concentrations are associated with adiposity markers but not with adipocytokines implicated in inflammation. This lack of association does not support a major role of 25(OH) D in the pro-inflammatory environment observed in morbidly obese subjects. In addition, subjects with vitamin D deficiency are not characterized by a greater inflammatory state.     

Should more attention be paid to school performance in children and adolescents with diabetes?

Diabetes with onset in childhood and adolescence has consequences for the family and the child, and the negative health effects and burden of daily disease management are well known. Less is known about the socioeconomic consequences of the disease and how it impacts on school performance. In this issue of Diabetologia, Persson et al report from a Swedish study regarding the impact of childhood-onset type 1 diabetes on school performance (doi:10.1007/s00125-013-2870-8). Results indicate that onset of type 1 diabetes in childhood has adverse effects on school achievement and potentially on future successful employment. The authors suggest that attention must be paid in school to the particular needs of children with diabetes, although the question needs to be raised as to whether the differences are of such a magnitude that they matter and are relevant for healthcare and school personnel. The study provides a novel addition and is important because of the limited information available on educational performance among children and adolescents with diabetes. However, the results should be interpreted with caution because of the limitations of the study design, the relatively small differences detected and the fact that results from one country are not transferable to other countries without further research. The challenge is to find the resources to set up population-based studies in countries where appropriate data are available to investigate the long-term effects of type 1 diabetes on education and employment in different settings.     

Is disulphide/thiol ratio related to blood pressure in masked hypertension?

Dynamic thiol/disulphide homeostasis plays a critical role in numerous intracellular enzymatic pathways including antioxidant defence and detoxification. In this study, we sought to investigate dynamic thiol/disulphide homeostasis in patients with masked hypertension (MHT) and its relationship with blood pressure. Forty patients (23 men, 17 women) with newly diagnosed MHT and not yet on medical therapy, and 40 healthy volunteers (21 men, 19 women) were enrolled. Blood thiol/disulphide homeostasis was measured in both groups. Serum native and total thiol levels were measured using the novel, fully automated colorimetric method developed by Erel et al. Serum disulphide level was calculated as (serum total thiol???serum native thiol)/2. Native and total thiol levels (p?=?0.001) and native thiol/total thiol ratio (p?=?0.023) were found to be lower in patients with MHT when compared to those of the control group. Disulphide level and ratios of disulphide/native thiol and disulphide/total thiol were higher in patients with MHT than in the control group (p?=?0.001). A positive correlation of systolic blood pressure (SBP) and diastolic blood pressure (DBP) was observed with disulphide/native thiol ratio (p?<?0.001). Stepwise multivariable regression analysis showed disulphide/native thiol ratio to be an independent risk factor of SBP and DBP, and SBP to be an independent risk factor of disulphide/thiol ratio (p?=?0.001). In this study, we found that dynamic thiol/disulphide homeostasis shifted towards disulphide formation due to thiol oxidation in patients with MHT. Prospective randomised controlled studies are required to elucidate whether abnormal thiol/disulphide status lies in the pathogenesis of MHT or is a consequence of MHT.