ORIGINAL ARTICLE Adherence to a healthy Nordic food index and risk of myocardial infarction in middle-aged Danes: the diet, cancer and health cohort study VB Gunge 1 , I Andersen 2 , C Kyrø 1 , CP Hansen 3 , CC Dahm 3 , J Christensen 4 , A Tjønneland 1 and A Olsen 1 BACKGROUND/OBJECTIVES: For decades, the Mediterranean diet has been in focus regarding healthy eating as it has been associated with reduced risk of non-communicable diseases. Less interest has been given to health benefits of other regional diets. The aim of the present study was to assess whether adherence to a healthy Nordic food index was associated with lower risk of myocardial infarction (MI) among middle-aged Danes. SUBJECTS/METHODS: Data were obtained from the Danish Diet, Cancer and Health cohort study of 57 053 men and women aged 50 - 64 years recruited between 1993 and 1997. The healthy Nordic food index comprised healthy Nordic food items selected a priori (fish, cabbage, rye bread, oatmeal, apple and pears and root vegetables). Information on incident MI was ascertained through linkage with national registries. Hazard ratios (HR) with 95% confidence intervals (CI) were estimated from sex-specific Cox proportional hazard models. RESULTS: In total, 1669 men and 653 women developed MI during follow-up (13.6 median years). In adjusted models, those with an index score of 5 - 6 points (highest scores) had significantly lower MI risk (men: HR = 0.77, 95% CI = 0.62, 0.97; women: HR = 0.55, 95% CI = 0.37, 0.82) relative to those scoring 0 points in the index (lowest score). A significantly lower MI risk was found per 1-point increment in the index in both men (HR = 0.95, 95% CI = 0.92, 0.99) and women (HR = 0.93, 95% CI = 0.88, 0.98). CONCLUSIONS: A healthy Nordic diet is associated with lower MI risk among middle-aged Danes, suggesting that Nordic diets should be considered in recommendations for dietary changes in the promotion of coronary health. European Journal of Clinical Nutrition advance online publication, 1 March 2017; doi:10.1038/ejcn.2017.1 INTRODUCTION Myocardial infarction (MI) is a common presentation of coronary heart disease (CHD), a major cause of morbidity and mortality worldwide. 1 Around 80% of CHD cases are believed to be preventable by modifiable lifestyle factors, including a healthy diet. 1 Evidence consistently demonstrates lower risks of CHD with adherence to the Mediterranean diet in Mediterranean, American and other Western populations. 2 This has led to promotion of the Mediterranean diet in non-Mediterranean countries, including the Nordic countries. 3 However, differences in local resources and food cultures may restrain other populations from complying with the Mediterranean diet. A relevant field of study therefore is whether the lower risk of CHD applies for a healthy Nordic diet embracing food items originating from the Nordic climate within a Nordic population. Evidence emerging from Nordic studies suggest inverse associations between healthy Nordic diets or indices with total mortality risk, 4 colorectal cancer 5 and with cardiovascular risk factors. 6–10 The majority of studies, however, have been con- ducted in 'high-risk' populations, for instance, in centrally obese 11 or hypercholesterolaemic individuals, 7 and are thus not fully representative for the general population. To our knowledge, only one recent population-based study examined the association of a healthy Nordic food index with cardiovascular disease, including clinical diagnosis of CHD, and this study found no evidence of an association. 12 The association of adherence to a healthy Nordic diet in relation to coronary health thus remains unclear and warrants further investigation, particularly among the general healthy population. The Nordic diet has in general been characterised by its unhealthy features like sugar and high-fat dairy products. 13 This diet, however, also includes foods with anticipated health- enhancing effects, for example, apple and pears, whole-grain cereals and fish. The aim of this study is to investigate whether greater adherence to a healthy Nordic food index (HNFI) comprising healthy food items, that are part of the traditional Nordic diet, is associated with lower risk of MI in a cohort of middle-aged Danes. MATERIALS AND METHODS Study population The study is based on data from the Danish Diet, Cancer and Health cohort study. The enrolment and data collection procedures have previously been described. 14 In short, during 1993 - 1997, a total of 160 725 men and women living in greater Copenhagen or Aarhus areas were invited to participate in the cohort. Those invited also had to be aged 50 - 64 years, born in Denmark, and to have no diagnosis of cancer registered in the 1 Unit of Diet, Genes and Environment, Danish Cancer Society Research Centre, Copenhagen, Denmark; 2 Department of Public Health, Section of Social Medicine, University of Copenhagen, Copenhagen, Denmark; 3 Department of Epidemiology, School of Public Health, Aarhus University, Aarhus, Denmark and 4 Unit of Statistics, Bioinformatics and Registry, Danish Cancer Society Research Centre, Copenhagen, Denmark. Correspondence: A Olsen, Unit of Diet, Genes and Environment, Danish Cancer Society Research Centre, Strandboulevarden 49, Copenhagen DK-2100, Denmark. E-mail: anja@cancer.dk Received 7 May 2016; revised 25 September 2016; accepted 28 December 2016 European Journal of Clinical Nutrition (2017), 1 – 7 © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved 0954-3007/17 www.nature.com/ejcn