We eat foods not nutrients. What is more, we eat them in combinations. Consequently, capturing our complex food habits is likely an advantage in nutrition research. The overall aim of this doctoral thesis was therefore to investigate dietary patterns in the Swedish population –nutrient intakes, nutritional biomarkers and health aspects. Prostate cancer is the most common cancer among men in the developed world. However, the impact of dietary factors on disease risk is largely unknown. In Study I we investigated the association between a Mediterranean- and a Low-carbohydrate-high-protein dietary pattern and prostate cancer risk, in a cohort of elderly Swedish men. The latter (but not the former) was associated, inversely, with prostate cancer risk when taking validity in food records into account. Diet is one of our main exposure routes to environmental contaminants. Hence, such exposure could act as a mediating factor in the relation between diet and health. In Study II we investigated the association between; a Mediterranean- and a Low-carbohydrate-high-protein dietary pattern, as well as the official dietary recommendations, and circulating levels of environmental contaminants, in an elderly Swedish population. The first two patterns were positively related to levels of both persistent organic pollutants and heavy metals, whilst the dietary recommendations were inversely associated to dioxin and lead. Finally, although dietary patterns are likely to influence health, little is known about current dietary patterns in Sweden. In Study III we used a data-reduction method to identify dietary patterns in a nationwide sample of the Swedish population. Two major patterns were derived; a Healthy pattern of foods generally considered healthy (e.g. vegetables, fruits, fish and vegetable-oils) and a Swedish traditional pattern (with e.g. meats, potatoes, sauces, non-Keyhole milk-products, sweet-bakery products and margarine). Derived patterns were associated to population characteristics and the Healthy dietary pattern was inversely associated to anthropometric variables in Study IV. Dietary characteristics of the patterns were well reflected in correlations to nutrient intake and (to a lesser extent) in nutritional biomarkers. In conclusion dietary patterns for overall health should be considered, as well as other lifestyle-factors, when interpreting results in nutrition epidemiology and establishing dietary recommendations.