Phenotyping the Effects of Nutrient Quality on Metabolic Health : Starring the Liver & Adipose Tissue

• Main Author: Schutte, Sophie
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2018
• Subjects: Body fat; Insulin resistance; Nutrition; Nutrition research; Obesity; Oxidation; Pharmaceutical sciences; Public health
• ISBN: 9798380568692

The growing burden of obesity-related pathologies calls for effective dietary strategies that improve metabolic health of overweight and obese individuals. Chronic diet-related diseases are the result of perturbations in different metabolic organs and/or their elegant organ interplay, important metabolic organs in this respect are the liver and the adipose tissue. An evidently effective dietary strategy to correct metabolic parameters associated with chronic diseases is limiting the intake of daily calories, i.e. energy restriction (ER). In addition to lowering the energy quantity of the diet, increasing the quality of the diet by consuming more high quality nutrients can also be an appealing dietary approach. Poor quality Western-type diets rich in refined wheat, sugars including fructose, and SFA are an important risk factor of ill health. Combining multiple high quality nutrients within an ER-diet might be an even more powerful whole diet approach.However, measuring the effects of dietary strategies is challenging as effects of nutrition on health are usually relatively subtle may take a long time to manifest. In addition, classical blood markers assessed in nutritional intervention studies are typically late disease markers. To be able to more precisely assess the effect of dietary interventions and to elucidate underlying mechanisms, we need to adopt a comprehensive phenotyping approach in which we combine classical markers with sensitive measures, such as the ability of an individual to deal with a dietary stressor, i.e. phenotypic flexibility, and extensive high-throughput techniques. The aim of this thesis was to assess the effects of nutrient quality on metabolic health with a specific focus on the liver and adipose tissue, in overweight and obese individuals. Therefore, we applied comprehensive phenotyping, ~omics techniques, and standardized mixed meal challenge tests in two human intervention studies, one in which we studied nutrient quality within eucaloric diets and one in which nutrient quality within ER-diets was examined In addition, we executed an observational study to elucidate the physiological function and regulation of two important metabolic regulators in the liver and adipose tissue, ANGPTL4 and LPL.The effects of nutrient quality within eucaloric diets were studied in Chapter 2,in which we examined the effects of a 12 week intervention with either refined wheat or whole grain wheat bread and cereals in overweight and obese individuals. Consumption of the low nutrient quality refined wheat resulted in a pronounced increase in intrahepatic lipids. Furthermore, refined wheat consumption was associated with a decrease in gut microbiota diversity. Whole grain wheat consumption induced a trend towards lower fasting levels of liver acute phase proteins and an increase in postprandial triglycerides after a mixed meal, which may indicate greater hepatic triglyceride output. Incorporating feasible doses of whole grain wheat in the diet at the expense of refined wheat thus favorably affects liver health.The effects of nutrients quality within ER-diets were studied in Chapter 3-5,in which we examined the effects of a high quality ER-diet rich in soy protein, fiber, MUFA, and n-3 PUFA and a low nutrient quality Western-type ER-diet in subjects with abdominal obesity. Both diets induced clinically relevant weight loss after 12 weeks, accompanied by reductions in subcutaneous and visceral fat mass and intrahepatic lipids.