Genetic variation not only predisposes to disease, but also influences physiological processes in the human body. Some of these influence how our internal biochemistry works, for example how efficiently our organism can specific nutrients. As an example, genetic variants in a key protein of the human lipid metabolism (FADS1), change levels of omega-3 and omega-6 fatty acids in blood, but also influence the risk of developing cancer. In this project we aim at obtaining a better understanding of these processes at this specific example, especially focusing on how multiple genetic variants may interact in the process of developing cancer. If successful, our work may help mitigate the risk of developing cancer by providing a better understanding of the biochemical process that underlie its development, and to find out whether some fatty acids may be more beneficial to protect the body from disease than others.