From bugs to buttermilk: Epidemiological and molecular aspects of gut health

In the Netherlands, one in ten people suffers from gut complaints (functional gastrointestinal disorders), which can have a high negative impact on their daily activities. Because diagnosis and treatment are not straightforward, and are often impeded by the multiple factors that play a role in gut health, it is important to improve our knowledge about gut health to aid in future diagnosis and treatment of this prevalent disorder. In this thesis I describe our research on several aspects of gut health. The major focus is on the interaction between the gut microbiota and environmental factors and on its link to gut health. We find associations between microbiota composition and 126 factors including stool consistency, smoking and buttermilk consumption. In addition, I describe the associations between food intake and gut complaints. I find, for example, a lower intake of fiber and a higher intake of meat in people with gut complaints. With regard to the relation between overall wellbeing and gut health, I find an association between more severe gut complaints and a lower quality of life. I also present the results of our search for a biomarker panel to aid in the diagnosis of gut complaints. For this panel, we identified a combination of eight components originating from blood or feces that best discriminates between patients with severe gut complaints and healthy controls, and we see a correlation between this biomarker panel and the severity of gut complaints