Study of the association between 3111T/C polymorphism of the CLOCK gene and the presence of overweight in schoolchildren

Chrononutrition-When We Eat Is of the Essence in Tackling Obesity

Obesity is a chronic and relapsing public health problem with an extensive list of associated comorbidities. The worldwide prevalence of obesity has nearly tripled over the last five decades and continues to pose a serious threat to wider society and the wellbeing of future generations. The pathogenesis of obesity is complex but diet plays a key role in the onset and progression of the disease. The human diet has changed drastically across the globe, with an estimate that approximately 72% of the calories consumed today come from foods that were not part of our ancestral diets and are not compatible with our metabolism. Additionally, multiple nutrient-independent factors, e.g., cost, accessibility, behaviours, culture, education, work commitments, knowledge and societal set-up, influence our food choices and eating patterns. Much research has been focused on 'what to eat' or 'how much to eat' to reduce the obesity burden, but increasingly evidence indicates that 'when to eat' is fundamental to human metabolism. Aligning feeding patterns to the 24-h circadian clock that regulates a wide range of physiological and behavioural processes has multiple health-promoting effects with anti-obesity being a major part. This article explores the current understanding of the interactions between the body clocks, bioactive dietary components and the less appreciated role of meal timings in energy homeostasis and obesity.

Sleep, nutritional status and eating behavior in children: a review study

OBJECTIVE

To review the current literature on the relationship between sleep, nutritional status and eating behavior, as well as mechanisms associated with these elements in children.

DATA SOURCE

The literature research was conducted in the PubMed, LILACS and Scopus databases, using the following terms: "Child"; "Nutritional status"; "Sleep"; "Physical activity OR Physical activities OR Exercise". The articles included were those that met the research objective. Review articles, letters to authors, or guidelines were excluded.

DATA SYNTHESIS

402 articles were initially found in the literature search. After careful analyses of the title and abstract, and application of inclusion criteria, only 24 studies were included in the present review. Most studies (n=13) suggest that short sleep duration (<9-10 hours/night) is associated with overweight/obesity in children. Only three studies did not show associations between overweight/obesity and sleep variables. Short sleep duration is also associated with poor food quality, higher intake of soft drinks and stimulant beverages before bedtime, as well as micronutrient deficiency.

CONCLUSIONS

Sleep duration is related to overweight and obesity development in infants. Changes in dietary pattern are also related to sleep debt, being one of the mechanisms that contribute to excessive weight gain. It is necessary that health professionals understand the importance of sleep quality in the nutritional status maintenance in children.

Sono, estado nutricional e hábitos alimentares em crianças: um estudo de revisão

RESUMO Objetivo: Fazer uma revisão da literatura sobre a relação entre sono, estado nutricional e padrão alimentar, bem como mecanismos associados, na população infantil. Fontes de dados: Foram realizadas buscas bibliográficas nas bases PubMed, LILACS e Scopus, usando os seguintes descritores: “Child”; “Nutritional status”; “Sleep”; “Physical activity OR Physical activities OR Exercise”. Os artigos que atenderam ao objetivo da pesquisa foram incluídos. Excluíram-se estudos de revisão, cartas para autores ou diretrizes. Síntese dos dados: Inicialmente, 402 artigos foram encontrados na pesquisa. Após análise dos títulos e abstracts e a aplicação dos critérios de exclusão, 24 estudos foram selecionados para a revisão. A maioria dos estudos (n=13) sugere que sono de curta duração (<9-10 horas/noite) está associado com sobrepeso/obesidade na população infantil. Apenas três artigos não reportaram associações entre variáveis do sono e estado nutricional. Curta duração do sono também foi associada a hábitos alimentares ruins, maior consumo de refrigerantes e bebidas estimulantes antes de deitar, bem como deficiência de micronutrientes. Conclusões: A duração do sono tem relação com sobrepeso e obesidade na população infantil. Alterações no padrão alimentar também têm relação com débito de sono, sendo um dos mecanismos que contribuem para o ganho de peso excessivo. É necessário que os profissionais de saúde tomem conhecimento da importância da qualidade do sono para a manutenção do estado nutricional em crianças.

Daily Rhythm of Fractal Cardiac Dynamics Links to Weight Loss Resistance: Interaction with CLOCK 3111T/C Genetic Variant

The effectiveness of weight loss treatment displays dramatic inter-individual variabilities, even with well-controlled energy intake/expenditure. This study aimed to determine the association between daily rhythms of cardiac autonomic control and weight loss efficiency and to explore the potential relevance to weight loss resistance in humans carrying the genetic variant C at CLOCK 3111T/C. A total of 39 overweight/obese Caucasian women (20 CLOCK 3111C carriers and 19 non-carriers) completed a behaviour–dietary obesity treatment of ~20 weeks, during which body weight was assessed weekly. Ambulatory electrocardiographic data were continuously collected for up to 3.5 days and used to quantify the daily rhythm of fractal cardiac dynamics (FCD), a non-linear measure of autonomic function. FCD showed a 24 h rhythm (p < 0.001). Independent of energy intake and physical activity level, faster weight loss was observed in individuals with the phase (peak) of the rhythm between ~2–8 p.m. and with a larger amplitude. Interestingly, the phase effect was significant only in C carriers (p = 0.008), while the amplitude effect was only significant in TT carriers (p < 0.0001). The daily rhythm of FCD and CLOCK 3111T/C genotype is linked to weight loss response interactively, suggesting complex interactions between the genetics of the circadian clock, the daily rhythm of autonomic control, and energy balance control.

Adequate sleep duration among children and adolescents: a review of the Brazil's Report Card

abstract – This study aimed to summarize existing research examining the prevalence of adequate sleep duration or meeting sleep recommendations among Brazilian children and adolescents. A systematic review was conducted on eight databases. The criteria for inclusion were original research, samples including Brazilian children and adolescents (age 0–18), studies that reported variables regarding sleep duration using both objective or subjective measures, school- or population-based surveys with random sampling, and cross-sectional or cohort studies. Of the 54 articles included, only 27 used data from different studies. Most of the studies were conducted in the southern region (n = 17) with only two studies having a nationally representative sample. Two studies included children below age five, and the age group most investigated was adolescents (>10 years old). A majority of the studies used a self-reported questionnaire and showed variability in the cutoff point applied for adequate sleep duration with the most reported being ≥8 hours. The proportion of adolescents who met recommendations or had adequate sleep duration ranged from 15% to 89%. Among children, the prevalence ranged from 17% to 95%. The least variability was observed among toddlers, ranging from 93% to 95%. No consistent gender differences were observed among the gender-stratified groups of children and adolescents across the studies. It can be observed that, because of the wide range of results and the lack of data with national representativeness, the prevalence of sufficient sleep among young people aged below 18 remains undefined in Brazil.

Sex modifies the association between the CLOCK variant rs1801260 and BMI in school-age children

Disruption of circadian rhythms and variations in the FTO gene may interfere with energy homeostasis and play a role in the development of obesity. The current study assessed the association of common polymorphisms in the CLOCK and FTO genes with standardized body mass index scores (BMI z-scores) and their potential modification of the impact of a culinary nutrition and physical activity intervention in school-age children. Anthropometric measurements were collected in 121 children at the baseline and one-year follow-up of a controlled trial of a school-based culinary nutrition and physical activity intervention. Genotypes of the CLOCK polymorphism (rs1801260) and the FTO polymorphism (rs9939609) were obtained from buccal swabs. Linear mixed-effects regression was applied to evaluate the genetic association and adjust for clusters within families and schools. In our participants, obesity affected 6.6% (8/121) of the children at the baseline and 6.4% (7/109) of the children at the follow-up. The associations between the age- and sex-adjusted BMI z-scores and the two polymorphisms did not reach statistically significance. Yet, sex potentially modified the association between rs1801260 and BMI z-scores. In girls, the G allele carriers had a higher BMI z-scores at the baseline and the follow-up. These polymorphisms did not modify the effect of our culinary nutrition and physical activity intervention on BMI z-scores. Sex is a potential modifier for the association between the CLOCK polymorphism, rs1801260, and BMI z-scores in school-age children. Further investigation is warranted to delineate the sex-dependent role of the CLOCK polymorphisms in the development of childhood obesity.

Sleep and obesity among children: A systematic review of multiple sleep dimensions

The objectives were to systematically investigate the multiple dimensions of sleep and their association with overweight or obesity among primary school-aged children. CINHAL, PsycINFO, SPORTDiscus, Medline, Cochrane, Embase, and PubMed databases were searched for papers reporting on an association between children's sleep and weight status. Studies on clinical populations, published in languages other than English, without objectively measured weight status, or where weight status was reported outside the outlined age bracket (5-13 years) were excluded. A total of 34  248 citations were extracted from our systematic search protocol, of which 112 were included for detailed review. Compared with sleep duration, of which 86/103 articles found a significant inverse association between sleep duration and measured weight status, few studies examined other dimensions of sleep, such as quality, efficiency and bed/wake times, and relationship with weight status. Where studies existed, variation in defining and measurement of these dimensions restricted comparison and potentially influenced discrepancies across results. Overall, the findings of this review warrant the need for further research of the outlined dimensions of sleep. Future research would benefit from clarity on definitions across the different dimensions, along with the use of valid and reliable tools.

Trp64Arg polymorphism of the ADRB3 gene associated with maximal fat oxidation and LDL-C levels in non-obese adolescents

OBJECTIVE

To analyze the association between the Trp64Arg polymorphism of the ADRB3 gene, maximal fat oxidation rates and the lipid profile levels in non-obese adolescents.

METHODS

72 schoolchildren, of both genders, aged between 11 and 17 years, participated in the study. The anthropometric and body composition variables, in addition to total cholesterol, HDL-c, LDL-c, triglycerides, insulin, and basal glycemia, were evaluated. The sample was divided into two groups according to the presence or absence of the polymorphism: non-carriers of the Arg64 allele, i.e., homozygous (Trp64Trp: n=54), and carriers of the Arg64 allele (Trp64Arg+Arg64Arg: n=18), in which the frequency of the Arg64 allele was 15.2%. The maximal oxygen uptake and peak of oxygen uptake during exercise were obtained through the symptom-limited, submaximal treadmill test. Maximal fat oxidation was determined according to the ventilatory ratio proposed in Lusk's table.

RESULTS

Adolescents carrying the less frequent allele (Trp64Arg and Arg64Arg) had higher LDL-c levels (p=0.031) and lower maximal fat oxidation rates (p=0.038) when compared with non-carriers (Trp64Trp).

CONCLUSIONS

Although the physiological processes related to lipolysis and lipid metabolism are complex, the presence of the Arg 64 allele was associated with lower rates of FATMAX during aerobic exercise, as well as with higher levels of LDL-c in adolescents.

CLOCK 3111T/C genetic variant influences the daily rhythm of autonomic nervous function: relevance to body weight control

BACKGROUND/OBJECTIVES

Humans carrying the genetic risk variant C at the circadian CLOCK (Circadian Locomotor Output Cycles Kaput) 3111T/C have been shown to have more difficulties to achieve desired weight loss than TT carriers. We tested the hypothesis that the daily rhythm of autonomic nervous function differs in CLOCK 3111C carriers, leading to reduced effectiveness in weight control.

SUBJECTS/METHODS

We recruited 40 overweight/obese Caucasian women (body mass index>25), 20 carrying CLOCK 3111C (CC and TC) and 20 non-carriers with matched age and body mass index who participated in a dietary obesity treatment program of up to 30 weeks. Following the treatment, ambulatory electrocardiography was continuously monitored for up to 3.5 days when subjects underwent their normal daily activities. To assess autonomic function, heart rate variability analysis (HRV) was performed hourly to obtain mean inter-beat interval between two consecutive R waves (mean RR) and s.d. of normal-to-normal heartbeat intervals (SDNN), and two parasympathetic measures, namely, proportion of differences between adjacent NN intervals that are >50 ms (pNN50), and high-frequency (HF: 0.15-0.4 Hz) power.

RESULTS

In the TT carriers, all tested HRV indices showed significant daily rhythms (all P-values <0.0001) with lower mean RR, SDNN, pNN50, and HF during the daytime as compared with the nighttime. The amplitudes of these rhythms except for SDNN were reduced significantly in the C carriers (mean RR: ~19.7%, P=0.001; pNN50: 58.1%, P=0.001; and HF: 41.1%, P=0.001). In addition, subjects with less weight loss during the treatment program had smaller amplitudes in the rhythms of mean RR (P<0.0001), pNN50 (P=0.007) and HF (P=0.003). Furthermore, the rhythmicity-weight loss associations were much stronger in the C carriers as compared to the TT carriers (mean RR: P=0.028, pNN50: P=0.0002; HF: P=0.015).

CONCLUSIONS

The daily rhythm of parasympathetic modulation may play a role in the influence of the CLOCK variation on body weight control.

Association between genetic variants of the clock gene and obesity and sleep duration

Obesity is a multifactorial disease caused by the interaction of genetic and environmental factors related to lifestyle aspects. It has been shown that reduced sleep is associated with increased body mass index (BMI). Circadian Locomotor Output Cycles Kaput (CLOCK) gene variants have also been associated with obesity. The objective of this mini-review was to discuss the available literature related to CLOCK gene variants associated with adiposity and sleep duration in humans. In total, 16 articles complied with the terms of the search that reported CLOCK variants associated with sleep duration, energy intake, and BMI. Overall, six CLOCK single nucleotide polymorphisms (SNPs) have been associated with sleep duration, and three variants have been associated with energy intake variables. Overall, the most studied area has been the association of CLOCK gene with obesity; close to eight common variants have been associated with obesity. The most studied CLOCK SNP in different populations is rs1801260, and most of these populations correspond to European populations. Collectively, identifying at risk CLOCK genotypes is a new area of research that may help identify individuals who are more susceptible to overeating and gaining weight when exposed to short sleep durations.