Precision Nutrition through dietary, behavioural, phenotypic and nutrigenetic information in an internet-based personalised intervention

Obesity is characterised by an increase of body weight, due to a chronic imbalance between energy intake and expenditure. Sustained accumulation of excessive adipose tissue has been described to be associated with an increased risk of type 2 diabetes, hypertension, blood disorders, cardiovascular diseases, certain cancers, as well as a wide range of psychological problems. Strategies struggling the obesogenic environmental factors through the improvement of lifestyle habits and nutritional behaviour are being carried out worldwide to prevent the increase of obesity. At the same time, the advances and the increasing interest on omic sciences are promoting the perspectives on the application of Precision Nutrition based on environmental, dietary, phenotypic and genotypic information. Furthermore, the widespread use of on-line services, has enabled internet-based personalised counselling in order to achieve changes in healthy behaviour. Based on this evidence, the present dissertation aims to evaluate the feasibility of internet-based nutritional advice and to design accurate and fast tools to help health professionals to provide specific diagnostics and personalised nutritional advices in an European population interested in Precision Nutrition. First of all, a prospective exploration of commercial panels of genetic tests concerning obesity and related metabolic traits was performed in Chapter 1. Heterogeneity of analytical techniques, as well as in the number of genes analysed and the price of the products were exhibited at the moment of the research, however variations in 22 obesity-related genes were observed to be shared in at least two laboratories. Subsequently, different approaches for the nutritional status assessment were carried out in the Food4Me participants. A shortened questionnaire of 9 items (NPSQ9) was derived in Chapter 2 through multifactorial analysis from questions linked to the self-perception towards healthy eating. The score obtained from the NPSQ9 exhibited to be associated with nutritional status and with greater dietary improvements during the nutritional intervention. Furthermore, in Chapter 3, an isocaloric substitution regression model showed a reduction in the presence of obesity when dietary vegetable protein sources were increased instead of animal protein and simple sugars. According to this result, in Chapter 4 a retrospective multivariate analysis of dietary intake revealed the existence of 4 dietary patterns ( Prudent , Healthy , Western and Compensatory ), which were differently associated with the prevalence of obesity. These results highlighted the importance of reducing unhealthy food choices in addition to enhancing healthy eating behaviours for the prevention of obesity. Finally, behavioural eating patterns were analysed to determine the associations with phenotypic and genotypic variables throughout the personalised intervention. Hence, in Chapter 5 it was found that received Personalised Nutrition advice was associated with higher adherence to Mediterranean diet after 6 months of intervention and the addition of genotypic information achieved larger improvements. On the other hand, Chapter 6 showed that individuals presenting risk alleles in the FTO gene and unhealthy dietary behaviours were related to present greater ponderal status. Finally, Chapter 7 demonstrated that an elevated adherence to Mediterranean diet might overcome some of the adverse effects associated to the genetic make-up on anthropometrics. However, a modulating effect was reflected in lipid metabolism-related traits by the genetic background. In addition, buccal swab samples as a surrogated non-invasive tissue were analysed in Chapter 8 for the identification of epigenetic marks concerning obesity and related traits. The results presented the parallelism between buccal and blood samples in the methylation levels of obesity-related genes, exhibiting the potential use of buccal sample in clinical practice.