Peripheral body fat, lifestyles and adipokins
Instituto de Saúde Pública da Universidade do Porto (ISPUP), Unidade de Investigação e Desenvolvimento Cardiovascular (UIDC/FM/UP), Faculdade de Medicina da Universidade do Porto (FMUP)
The amount and type of body fat distribution, rather than general obesity, seem to determine a differential production of adipokines inflammatory proteins produced by the adipocytes, known to have an important role in atherosclerosis. Central fat has been described to have a direct association with some adipokines levels, such as leptin and an inverse association with adiponectin, but the role of peripheral fat fat accumulated in the upper or/and lower members, on adipokines levels has been neglected, probably due to its potential opposing effects to central fat and also due to methodological limitations related to its measurement.
Therefore, firstly this project aims to validate a simple method of prediction of the total peripheral fat in the body, using anthropometric measures (skinfold thickness and body circumferences), which could further be used in future large-scale population-based studies. Then, we intend to study the peripheral vs. central fat effects on adipokine levels (adiponectin and leptin), regarding sex-related differences, since a gender-effect on these associations is expected.
Moreover, we propose to relate the adipokine levels with lifestyles, namely diet, physical activity, alcohol intake and smoking for clarifying their influence in the adipose tissue distribution and its metabolic products. Different approaches (single nutrients and dietary patterns) and methodologies (food questionnaires and biochemistry measurements) of studying diet and the possibility of having repeated information on physical activity, alcohol and smoking habits will assure a more comprehensive understanding of these associations.
This project is based on a prospective cohort of 2485 non-institutionalized adults (≥18 years), representative of the Porto population - the EPIPorto study, which represents an exceptional methodological advantage. This project will include all the participants aged between 18-60 years, to minimize some body fat redistribution, which occurs frequently with ageing. We will be able to use a set of information already collected for these participants during the baseline (1999-2003, n=1645) and the follow-up assessments (2005-2008, n=917), and collect new information, under the supervision of a research team, widely experienced in the collection, storing and analysis of data of large population cohorts. Data will be gathered, according to standardized procedures and techniques, by a well-trained health professional.
In a sub-sample of 300 subjects, data on anthropometrics (weight, height, skinfold thickness and body circumferences) and bioelectric impedance of two compartments will be newly collected. These same participants will undertake a measurement of the peripheral fat of the body, by a dual-energy x-ray absorptiometry (DXA) equipment. To estimate dietary intake an 86-item semi-quantitative food-frequency questionnaire formerly validated for the adult Portuguese population by our group, will be applied, by face-to-face interviews. A blood sample will be also collected to perform measurements of adiponectin and leptin levels, as well as the fatty acid profile of the erythrocyte membranes. Biochemistry measurements of adipokines serum concentrations will be also performed in more 1200 participants of EPIPorto, for whom serum samples are stored. For the same participants, information on potential confounders and lifestyles, such as diet, physical activity, alcohol intake and smoking are already available.
This study will provide important insights on the unknown effects of peripheral body fat on adipokines, taking into account gender differences, and enhance the knowledge on the influence of modifiable lifestyles on adipokines, which may be important factors linking obesity to individual cardiovascular outcomes.