Adults with end-stage kidney disease (ESKD) treated with haemodialysis (HD) experience 15-20% mortality each year, mostly due to excess cardiovascular causes. Despite decades of research, the high rates of premature death remain largely unchanged. There is an unmet need for strategies to reduce this risk. Dietary modifications are important potential lifestyle intervention to improve health outcomes in HD and have been prioritized as an important area of research uncertainty by patients and healthcare professionals. The aim of this thesis is to investigate the association between diet at different levels (nutrients, food groups and dietary patterns) and survival in adults receiving HD. The “DIETary intake, death and hospitalization in adult with end-stage kidney disease treated with Haemodialysis (DIET-HD) study”, an international prospective cohort study of around 10000 patients treated with HD in Europe and South America, is the core of this work. The primary exposure of the study was informed by a systematic review of randomized controlled trials evaluating the benefits and harms of omega-3 fatty acids (n-3 PUFA) supplementation in chronic kidney disease. Low quality evidence suggested some cardiovascular benefit of omega-3 supplements in HD patients. However, this survival benefit was not seen in patients with higher consumption of dietary n-3 PUFA within the DIET-HD study. Overall, while the DIET-HD study found no association between n-3 PUFA dietary intake, existing dietary patterns considered healthy in the general population (such as Mediterranean and Dietary Approaches to Stop Hypertension diets) or data driven dietary patterns specific to the HD population and mortality, there was some evidence that higher fruit and vegetable intake may be associated with reduced all-cause death through non-cardiovascular pathways. Definitive answers on the role of diet on the health of HD patients will be provided only by large-scale, pragmatic interventions studies.