Dietary quality, greenhouse gas emissions related to food consumption, and human health: A population-based cohort study in northern Sweden

Abstract

The overall aim of this thesis was to assess dietary quality and dietary-related greenhouse gas emissions (GHGEs), and their association with health outcomes, in a population-based cohort in northern Sweden. Dietary data were collected among participants within the cohort Västerbotten Intervention Programme by a food frequency questionnaire between 1990–2016. Dietary GHGEs were estimated using the RISE Food and Climate Database. Dietary nutrient density was calculated by the Nutrient Rich Foods (NRF) index in Study I and Study II. In Study I, fifteen variants of the NRF index were evaluated and the index version that best predicted all-cause mortality was further used to estimate participants' nutrient density in Study I and Study II. In Study III, diet quality was assessed by the Swedish Healthy Eating Index for Adults 2015 (SHEIA15), based on the 2015 Swedish food-based dietary guidelines. Cox proportional hazard regressions were performed to investigate associations between dietary aspects and health outcomes. Study I investigated associations between the NRF index and all-cause mortality, as well as associations between diets with varying levels of nutrient density and GHGEs, and all-cause mortality. The NRF11.3 index was indicated as a predictor of mortality hazard. The study also showed that diets with higher nutrient density and lower GHGEs were associated with lower mortality hazards in women, and that diets with lower nutrient density and lower GHGEs were associated with higher mortality hazards in men. Study II investigated associations between diets with different levels of nutrient density and GHGEs, and myocardial infarction (MI), and stroke. The NRF11.3 index was not indicated as a predictor of MI or stroke. A negative association was however shown between diets with lower GHGEs and MI hazard in men. Study III investigated the association between SHEIA15, and both all-cause mortality and dietary GHGEs. Lower all-cause mortality hazards and lower dietary GHGEs were indicated with higher SHEIA15 scores. This thesis demonstrated both potential co-benefits and trade-offs between dietary quality, GHGEs of self-reported diets, and health outcomes in a Swedish population. Furthermore, two indices assessing different aspects of dietary quality of Swedish diets were suggested as predictors of all-cause mortality, of which one was further suggested as a predictor of dietary GHGEs.