Influence of a healthy Nordic diet on serum fatty acid composition and associations with blood lipoproteins : results from the NORDIET study

Background: The fatty acid (FA) composition of serum lipids is related to the quality of dietary fat. The aim of this study was to investigate the effects of a healthy Nordic diet (ND) on the FA composition of serum cholesterol esters (CE-FA) and assess the associations between changes in the serum CE-FA composition and blood lipoproteins during a controlled dietary intervention. Methods: The NORDIET trial was a six-week randomised, controlled, parallel-group dietary intervention study that included 86 adults (53±8 years) with elevated low-density lipoprotein cholesterol LDL-C. Serum CE-FA composition was measured using gas chromatography. Diet history interviews were conducted, and daily intake was assessed using checklists. Results: Food and nutrient intake data indicated that there was a reduction in the fat intake from dairy and meat products and an increase in the consumption of fatty fish with the ND, decreasing the levels of saturated fatty acids (SFA) in the diet, slightly decreasing the levels of monounsaturated fatty acids (MUFA) and moderately increasing the levels of polyunsaturated fatty acids (PUFA). Concomitantly, the levels of CE-SFA 14:0, 15:0 and 18:0, but not 16:0, decreased during the ND, and these changes differed from those observed in the control diet group (p<0.01). In contrast, serum 22:6n-3 increased during the ND compared with the control diet (p<0.01). The changes in CE-SFA 14:0, 15:0 and 18:0 during the intervention correlated positively with those in LDL-C, HDL-C, LDL-C/HDL-C, ApoA1 and ApoB (p<0.01), whereas the changes in CE-PUFA 22:6n-3 were negatively correlated with changes in the corresponding serum lipids. Conclusions: The decreased intake of saturated fat and increased intake of n-3 PUFA in a healthy Nordic diet are partly reflected by changes in the serum CE-FA composition, which are associated with an improved serum lipoprotein pattern