Effects of an isocaloric healthy Nordic diet on insulin sensitivity, lipid profile and inflammation markers in metabolic syndrome -- a randomized study (SYSDIET).

BACKGROUND: Different healthy food patterns may modify cardiometabolic risk. We investigated the effects of an isocaloric healthy Nordic diet on insulin sensitivity, lipid profile, blood pressure and inflammatory markers in people with metabolic syndrome. METHODS: We conducted a randomized dietary study lasting for 18-24 weeks in individuals with features of metabolic syndrome (mean age 55 years, BMI 31.6 kg m(-2) , 67% women). Altogether 309 individuals were screened, 200 started the intervention after 4-week run-in period, and 96 (proportion of dropouts 7.9%) and 70 individuals (dropouts 27%) completed the study, in the Healthy diet and Control diet groups, respectively. Healthy diet included whole-grain products, berries, fruits and vegetables, rapeseed oil, three fish meals per week and low-fat dairy products. An average Nordic diet served as a Control diet. Compliance was monitored by repeated 4-day food diaries and fatty acid composition of serum phospholipids. RESULTS: Body weight remained stable, and no significant changes were observed in insulin sensitivity or blood pressure. Significant changes between the groups were found in non-HDL cholesterol (-0.18, mmol L(-1) 95% CI -0.35; -0.01, P = 0.04), LDL to HDL cholesterol (-0.15, -0.28; -0.00, P = 0.046) and apolipoprotein B to apolipoprotein A1 ratios (-0.04, -0.07; -0.00, P = 0.025) favouring the Healthy diet. IL-1 Ra increased during the Control diet (difference -84, -133; -37 ng L(-1) , P = 0.00053). Intakes of saturated fats (E%, beta estimate 4.28, 0.02; 8.53, P = 0.049) and magnesium (mg, -0.23, -0.41; -0.05, P = 0.012) were associated with IL-1 Ra. CONCLUSIONS: Healthy Nordic diet improved lipid profile and had a beneficial effect on low-grade inflammation.