No association between adherence to the healthy Nordic food index and cardiovascular disease amongst Swedish women: a cohort study.

BACKGROUND
In several intervention trials, a healthy Nordic diet showed beneficial effects on markers of cardiovascular disease. We investigated the association between a healthy Nordic diet and clinical diagnosis of cardiovascular disease.

OBJECTIVE
Our aim was first to examine the association between a healthy Nordic food index (wholegrain bread, oatmeal, apples/pears, root vegetables, cabbages and fish) and the incidence of overall cardiovascular disease (ischaemic heart disease, stroke, arrhythmia, thrombosis and hypertensive disease), and secondly to test for possible effect modification by smoking, body mass index (BMI), alcohol consumption and age.

METHODS
We conducted an analysis of data from the prospective Swedish Women's Lifestyle and Health cohort, including 43 310 women who completed a food frequency questionnaire in 1991-1992, and followed up until 31 December 2012 through Swedish registries. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards models.

RESULTS
During follow-up, 8383 women developed cardiovascular disease. We found no association between the healthy Nordic food index and overall cardiovascular disease risk or any of the subgroups investigated. There was a statistically significant interaction with smoking status (P = 0.02), with a beneficial effect only amongst former smokers (HR 0.96, 95% CI 0.94-0.99 per 1-point increment).

CONCLUSION
The present results do not support an association between a healthy Nordic food index and risk of cardiovascular disease in Swedish women. There was also no effect modification by alcohol intake, BMI or age. Our finding of an interaction with smoking status requires reproduction.