Epidemiology of Obesity in Children and Adolescents Prevalence and E
Epidemiology of Obesity in Children and Adolescents Luis Moreno, Iris Pigeot, and Wolfgang Ahrens, editors Despite adults’ best preventive efforts, childhood obesity is on the rise in most areas of the world, and with it the prevalence of Type 2 diabetes,
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Genetics and Nutrigenomics of Obesity Andreu Palou, M. Luisa Bonet, Francisca Serra, and Catalina Picó
Introduction The prevalence of overweight and obesity is rapidly increasing in westernized countries, both in the general population and in children (see International Obesity Task Force 2009, http://www.iotf.org/). The increased availability of palatable, energy dense foods and the reduced requirement for physical exertion during working and domestic life as well as during leisure time contribute to a sustained state of positive energy balance and are, no doubt, critical factors underlying this obesity pandemic. Additional clues could relate to specific changes in diet composition, such as reduction of monounsaturated fat (Moussavi et al. 2008) or increment in the n-6/n-3 polyunsaturated fatty acid ratio (Ailhaud et al. 2006). Yet, as previously stated, “it will be unwise to view these environmental factors in isolation from the biological factors that normally control body weight and composition, and the compelling evidence that interindividual differences in susceptibility to obesity have strong genetic determinants” (O’Rahilly and Farooqi 2006). Nowadays, substantive information has accumulated regarding the molecular constituents of physiological pathways controlling energy balance and body fat content in mammals. Analysis of these pathways has highlighted possible candidate genes whose variation – in terms of DNA sequence and/or epigenetic marks – might underlie the genetic basis of obesity and, more generally speaking, of variation in body fat mass and distribution. In turn, genetic studies can contribute significantly to understanding the physiology of weight regulation, mainly through the positional cloning of mutations that cause monogenic obesity syndromes in rodents and humans and the application of hypothesis-free approaches (such as genome-wide linkage and association studies) to reveal novel potential obesity-related genes for their subsequent physiological characterization. An overview of main genes whose variation has been implicated in human obesity is given in section on “Genetic influences in human obesity: A physiology-based overview”. Substantive information is also available regarding the effects of nutritional status and of specific nutrients and other dietary chemicals on the pathways controlling energy balance and adiposity in mammals. Nutrigenomics, a science at the interface between molecular nutrition and genomics, seeks to identify and understand the interrelationships between diet, genetic makeup and physiological responses which ultimately affect the individual’s health status and/or predisposition to disease, at a genome-wide level. Nutrigenomics studies how nutrients and diets impact on gene expression and function and how the individual genetic makeup modifies or conditions diet effects, nutrient requirements and A. Palou (), M.L. Bonet, F.S. Serra, and C. Picó Laboratory of Molecular Biology, Nutrition and Biotechnology (Nutrigenomics), University of the Balearic Islands (U
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