The effect of healthy Nordic diet on cardio-metabolic markers: a systematic review and meta-analysis of randomized controlled clinical trials.

Abstract

The Nordic diet (ND), is supposed to be associated with a reduced cardiovascular risk; however, clinical trials have led to inconsistent results regarding the effect of this diet on cardio-metabolic markers. Using systematic review and meta-analysis of randomized controlled trials (RCTs), this study aimed to investigate the effect of the ND on circulating levels of total, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) cholesterol, and triglyceride (TG), as well as blood pressure in human adults. PubMed, Scopus, ISI Web of Science, and Google Scholar were searched up to February 2018 for relevant articles. Random effects model was used to estimate the overall effects. Five RCTs consisting of 513 participants were included in the present review. The meta-analysis of five eligible studies showed that ND significantly reduces the total [weighted mean difference (WMD) = - 0.38mmol/l, 95% confidence interval (CI) - 0.76, - 0.01, P = 0.044] and LDL cholesterol (WMD = - 0.30mmol/l, 95% CI - 0.54, - 0.06, P = 0.013) levels compared with the control groups; however, none was seen for HDL cholesterol and TG levels. The meta-analysis of four eligible RCTs revealed that the ND significantly reduces the systolic (WMD = - 3.97mmHg, 95% CI - 6.40, - 1.54, P = 0.001) and diastolic blood pressure (WMD = - 2.08mmHg, 95% CI - 3.43, - 0.72, P = 0.003). The Nordic dietary pattern improves blood pressure and also some of blood lipid markers and it should be considered as a healthy dietary pattern.