Every year, millions of people throughout the world suffer from fragility fractures. Hip fractures are the most severe type of fractures and is associated with high burden of morbidity, healthcare costs and mortality. Worldwide about one in five women and one in ten men will suffer from a hip fracture in their lifetime. In the last decade the importance of a healthy diet for the prevention of fractures has been emphasized. Indeed, a healthy diet seems to be a key in preventing osteoporosis and many nutrients and bioactive components, including fatty acids, may play a role. We hypothesize that the estimated intake of specific dietary fatty acids will associate with the odds of osteoporosis and the risk of hip fractures. In this study we also aim to carry out a relative validation of the fatty acid intake from the FFQ by the use of biomarker fatty acid composition from adipose tissue in a sub sample of the cohort. Biomarker fatty acids in plasma and its different compartments (triglycerides (TG), phospholipids (PL), cholesteryl esters (CE)) as well as of adipose tissue and the erythrocyte and platelet membranes, are reflective of the dietary intake of different fatty acids. The analyses will be carried out in the Swedish Mammography Cohort (SMC) and the Cohort of Swedish Men (COSM) using data from the investigations 1997 and 2009. Data from the clinical cohorts will be used for the relative validation of estimated fatty acid intake from the FFQ. The project will start with data from SMC.