The Nordic diet and the risk of non-communicable chronic disease and mortality: a systematic review and dose-response meta-analysis of prospective cohort studies

We aimed to investigate the association between adherence to the Nordic diet (ND) and the risk of chronic disease. PubMed, Scopus, and ISI Web of Science were searched to February 2020 to find prospective cohort studies. The relative risks (RRs) were calculated using a fixed-effects/random-effects model. The certainty of evidence was rated using the GRADE approach. Thirteen prospective cohort studies with 930,153 participants were included. The RRs for the highest compared to the lowest category of adherence to the ND were 0.78 (95%CI: 0.69, 0.87; I (2) = 51%, n = 6) for all-cause mortality, 0.78 (95%CI: 0.74, 0.83; I (2) = 70%, n = 4) for cardiovascular mortality, 0.86 (95%CI: 0.80, 0.93; I (2) = 83%, n = 4) for cancer mortality, 0.88 (95%CI: 0.79, 0.98; I (2) = 3%, n = 3) for stroke, 0.80 (95%CI: 0.68, 0.95; I (2) = 47%, n = 3) for myocardial infarction, and 0.90 (95%CI: 0.82, 0.99; I (2) = 33%, n = 4) for type 2 diabetes. There was an inverse linear association between the ND score and the risk of mortality, and an inverse monotonic association for type 2 diabetes. The certainty in the estimates ranged from very low to low.