NAFLD cirrhosis and liver cancer are fairly common and severe diseases with limited knowledge on prevention, especially the role of diet composition for the development of these diseases are unclear. The main aim of this study is to investigate associations of substituting one particular food for another with different carbohydrate and/or fat composition on incidence of NAFLD cirrhosis and liver cancer in a middle-aged population of men and women. We have two primary research questions in this project: 1) Is an isocaloric substitution of foods high in saturated fat with foods high in unsaturated fat associated with a decreased risk of NAFLD cirrhosis and liver cancer in Swedish men and women? 2) Is an isocaloric substitution of foods low in fiber and/or whole-grains with foods high in fiber and/or whole-grains associated with a decreased risk of NAFLD cirrhosis and liver cancer in Swedish men and women? Our secondary questions are: 1) Is a caloric addition of foods high in unsaturated fat associated with a decreased risk of NAFLD cirrhosis and liver cancer in Swedish men and women? 2) Is a caloric addition of foods high in fiber and/or whole-grains associated with a decreased risk of NAFLD cirrhosis and liver cancer in Swedish men and women? We will investigate the present aims in a prospective cohort study of of the two pooled cohorts COSM and SMC. The findings of this project coulld increase our current knowldge on the link between diet composition and the development of severe liver disease. If clear and robust associations are found, this might have implications for the prevention of NAFLD cirrhosis and liver cancer.