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Effects of dietary polyphenol intake on metabolic syndrome, body composition and obesity-related inflammation

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Universitat de Barcelona. Facultat de Medicina i Ciències de la Salut

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[eng] INTRODUCTION:
Metabolic syndrome (MetS) is a clustering of different cardiovascular and cardiometabolic risk factors. In developed countries, MetS prevalence has risen to 20- 25% in the adult population, and its incidence is increasing. Public health strategies for MetS treatment and prevention are mainly focused on lifestyle modification, including dietary and physical activity promotion. Aligned with MetS, obesity is a multifactorial complex disease defined by excess of adipose mass, which occurs through adipocyte hypertrophy and hyperplasia. However, while waist circumference is a better predictor for CVD than BMI or body weight, it is an index of total adiposity, and it cannot differentiate visceral from subcutaneous adiposity. The adipose tissue is an endocrine organ that secretes a wide variety of inflammatory adipocytokines, such as TNF-alpha, IL-6, resistin, leptin, and adiponectin. Visceral adiposity is associated with a higher production of these inflammatory adipocytokines, leading to systemic inflammation, insulin resistance, and several obesity-related metabolic disorders.

Phenolic compounds, also known as polyphenols, are characterized by the presence of one or more aromatic rings and phenol structural units in its molecules. The main food sources of polyphenols in Mediterranean countries are coffee, fruits, red wine, and vegetable oils, especially olive oil, whereas in non-Mediterranean countries, coffee, tea, fruits, and wine were the main food sources. Moreover, a continuous and prolonged polyphenol intake is related to BP and adiposity lowering effects, improvements in lipid profile, and anti-inflammatory effects, which all act as CVD protectors.

OBJECTIVE:
The general objective of this thesis project is to evaluate the effect of a high dietary polyphenol intake included in an intensive weight-loss-oriented lifestyle intervention program on adiposity parameters and other cardiovascular risk factors in patients with MetS, as well as the mechanisms involved in these effects. Additionally, we aimed to estimate the dietary polyphenol intake in Spanish population from PREDIMED (PRevención con DIeta MEDiterránea) Plus and validate an updated version of a semi- quantitative food frequency questionnaire.

RESULTS:
The intake of polyphenol subclasses has been reported to have an impact on MetS components, especially HDL-cholesterol. Total polyphenol intake was not associated with a better profile concerning MetS components, except for high-density lipoprotein cholesterol (HDL-c), although stilbenes, lignans, and other polyphenols showed an
 
inverse association with blood pressure, fasting plasma glucose, and triglycerides. A direct association with HDL-c was found for all subclasses except lignans and phenolic acids. In the case of type 2 diabetes prevalence, catechins, proanthocyanidins, hydroxybenzoic acids, and lignans were inversely associated with type 2 diabetes. These associations were different depending on sex and BMI, that is, women and overweight participants obtained stronger inverse associations. In this sense, after one year of follow-up, increments in total polyphenol intake and some classes were inversely associated with better glucose levels and HbA1c. In the case of body composition, some classes of polyphenols and body adiposity markers determined by dual-energy X-Ray absorptiometry, mainly visceral adipose tissue, and total fat mass after one year of follow-up. When participants were categorized into tertiles according to changes in VAT after one-year of follow-up, an increase of VAT content, showed significant mean increasement in PAI-1, resistin and leptin levels. When comparing among tertiles of VAT showed significant differences in insulin, PAI-1 and c-peptide. Additionally, a validated food frequency questionnaire showed moderate reliability according to Mediterranean diet adherence and biological markers.

CONCLUSIONS:
In conclusion, dietary polyphenol intake improves MetS criteria, body composition, and obesity-related inflammatory markers and adipokines levels. Improvements in visceral adipose tissue are associated with improvements in cardiometabolic parameters, compared to body weight. Additionally, visceral adipose tissue reductions improvements in obesity-related inflammatory response.

# metadata.dc.description.abstract[].value
[cat] La síndrome metabòlica (MetS) és un agrupament de diferents factors de risc cardiovasculars i cardiometabòlics. Les estratègies de salut pública pel tractament i la prevenció de la MetS es centren principalment en la modificació de l'estil de vida. Dins del marc de la Dieta Mediterrània, els compostos fenòlics també coneguts com a polifenols, han demostrat que una ingesta contínua i prolongada de polifenols està relacionada amb una reducció del risc cardiovascular, incloent la reducció de la pressió arterial, paràmetres d’adipositat, millores en el perfil lipídic i efectes antiinflamatoris. L'objectiu d'aquesta tesi doctoral va ser avaluar l'efecte d'una ingesta de polifenols elevada, dins d’una intervenció d'estil de vida orientat a la pèrdua de pes, sobre paràmetres d'adipositat i altres factors de risc cardiovascular en pacients amb MetS. Addicionalment, estimar la ingesta dietètica de polifenols en la població de l’estudi PREDIMED (PRevención con DIeta MEDiterránea) Plus i validar una versió actualitzada d'un qüestionari de freqüència d’aliments semi-quantitatiu. Les conclusions d’aquesta tesi doctoral inclouen que la ingesta dietètica de polifenols millora els criteris de la MetS, la prevalença de diabetis tipus 2, i la composició corporal, especialment el teixit adipós visceral. A més, la reducció del teixit adipós visceral millora els nivells de paràmetres inflamatoris i adipoquines. Per últim, la validació d’eines de recollida d’informació nutricional amb marcadors biològics i l’adherència a patrons dietètics saludables, com la Dieta Mediterrània, permet classificar als individus en funció de la seva ingesta dietètica.

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Tesis Doctorals - Facultat - Medicina i Ciències de la Salut

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Effects of dietary polyphenol intake on metabolic syndrome, body composition and obesity-related inflammation