Nutrigenetics: a tool to provide personalized nutritional therapy to the obese

Guide and Position of the International Society of Nutrigenetics/Nutrigenomics on Personalized Nutrition: Part 2 - Ethics, Challenges and Endeavors of Precision Nutrition

Nutrigenetics considers the influence of individual genetic variation on differences in response to dietary components, nutrient requirements and predisposition to disease. Nutrigenomics involves the study of interactions between the genome and diet, including how nutrients affect the transcription and translation process plus subsequent proteomic and metabolomic changes, and also differences in response to dietary factors based on the individual genetic makeup. Personalized characteristics such as age, gender, physical activity, physiological state and social status, and special conditions such as pregnancy and risk of disease can inform dietary advice that more closely meets individual needs. Precision nutrition has a promising future in treating the individual according to their phenotype and genetic characteristics, aimed at both the treatment and prevention of disease. However, many aspects are still in progress and remain as challenges for the future of nutrition. The integration of the human genotype and microbiome needs to be better understood. Further advances in data interpretation tools are also necessary, so that information obtained through newer tests and technologies can be properly transferred to consumers. Indeed, precision nutrition will integrate genetic data with phenotypical, social, cultural and personal preferences and lifestyles matters to provide a more individual nutrition, but considering public health perspectives, where ethical, legal and policy aspects need to be defined and implemented.

From Genome-Wide Association Study to Phenome-Wide Association Study: New Paradigms in Obesity Research

Obesity is a condition in which excess body fat has accumulated over an extent that increases the risk of many chronic diseases. The current clinical classification of obesity is based on measurement of body mass index (BMI), waist-hip ratio, and body fat percentage. However, these measurements do not account for the wide individual variations in fat distribution, degree of fatness or health risks, and genetic variants identified in the genome-wide association studies (GWAS). In this review, we will address this important issue with the introduction of phenome, phenomics, and phenome-wide association study (PheWAS). We will discuss the new paradigm shift from GWAS to PheWAS in obesity research. In the era of precision medicine, phenomics and PheWAS provide the required approaches to better definition and classification of obesity according to the association of obese phenome with their unique molecular makeup, lifestyle, and environmental impact.

Personalized weight loss strategies-the role of macronutrient distribution

A large number of different dietary approaches have been studied in an attempt to achieve healthy, sustainable weight loss among individuals with overweight and obesity. Restriction of energy intake is the primary method of producing a negative energy balance leading to weight loss. However, owing to the different metabolic roles of proteins, carbohydrates and lipids in energy homeostasis, diets of similar overall energy content but with different macronutrient distribution can differentially affect metabolism, appetite and thermogenesis. Evidence increasingly suggests that the fuel values of calories provided by distinct macronutrients should be considered separately, as metabolism of specific molecular components generates differences in energy yield. The causes of variation in individual responses to various diets are currently under debate, and some evidence suggests that differences are associated with specific genotypes. This Review discusses all available systematic reviews and meta-analyses, and summarizes the results of relevant randomized controlled intervention trials assessing the influence of macronutrient composition on weight management. The initial findings of research into personalized nutrition, based on the interactions of macronutrient intake and genetic background and its potential influence on dietary intervention strategies, are also discussed.

Differential DNA methylation patterns between high and low responders to a weight loss intervention in overweight or obese adolescents: the EVASYON study

In recent years, epigenetic markers emerged as a new tool to understand the influence of lifestyle factors on obesity phenotypes. Adolescence is considered an important epigenetic window over a human's lifetime. The objective of this work was to explore baseline changes in DNA methylation that could be associated with a better weight loss response after a multidisciplinary intervention program in Spanish obese or overweight adolescents. Overweight or obese adolescents (n=107) undergoing 10 wk of a multidisciplinary intervention for weight loss were assigned as high or low responders to the treatment. A methylation microarray was performed to search for baseline epigenetic differences between the 2 groups (12 subjects/group), and MALDI-TOF mass spectrometry was used to validate (n=107) relevant CpG sites and surrounding regions. After validation, 5 regions located in or near AQP9, DUSP22, HIPK3, TNNT1, and TNNI3 genes showed differential methylation levels between high and low responders to the multidisciplinary weight loss intervention. Moreover, a calculated methylation score was significantly associated with changes in weight, BMI-SDS, and body fat mass loss after the treatment. In summary, we have identified 5 DNA regions that are differentially methylated depending on weight loss response. These methylation changes may help to better understand the weight loss response in obese adolescents.

Oxidative stress and inflammation interactions in human obesity

Obesity is often characterized by increased oxidative stress and exacerbated inflammatory outcomes accompanying infiltration of immune cells in adipocytes. The oxidative stress machinery and inflammatory signaling are not only interrelated, but their impairment can lead to an inhibition of insulin responses as well as a higher risk of cardiovascular diseases and associated features. Mitochondria, in addition to energy transformation, play a role in apoptosis, cellular proliferation, as well as in the cellular redox state control. Under certain circumstances, protons are able to re-enter the mitochondrial matrix via different uncoupling proteins, disturbing free radical production by mitochondria. Disorders of the mitochondrial electron transport chain, over-generation of reactive oxygen species, and lipoperoxides or alterations in antioxidant defenses have been reported in situations of obesity and type-2 diabetes. On the other hand, obesity has been linked to a low grade pro-inflammatory state, in which impairments in the oxidative stress and antioxidant mechanism could be involved. The current scientific evidence highlights the need of investigating the interplay between oxidative stress and inflammation with obesity/diabetes onset as well as the interactions of such factors either as a cause or consequence of obesity. The signaling mediated by the activation of inflammatory markers or nuclear factor kappa β and other transcription factors as central regulators of inflammation are key issues to understanding oxidative stress responses in obesity. This review aims at summarizing the main mechanisms and interplay factors between oxidative stress and inflammation in human obesity according to the last 10 years of research in the field.