Improvement of serum lipids and blood pressure during intervention with n-3 fatty acids was not associated with changes in insulin levels in subjects with combined hyperlipidaemia

Abstract

Objectives: To investigate the effect of an omega-3 fatty acid concentrate K85 on serum lipids, lipoproteins, insulin metabolism and blood pressure in subjects with combined hyperlipidaemia.

Design: After a run-in dietary period of 10 weeks, subjects were randomly allocated to receive either encapsulated K85 (n = 28) or corn oil (n = 29). The intervention was double-blind.

Setting: An outpatient centre in Stavanger, Norway.

Subjects: Fifty-seven of 141 individuals, who, after the run-in period continued to meet the inclusion criteria: serum triglycerides of > or = 2.0 mmol L-1 and total serum cholesterol of > or = 6.0 mmol L-1.

Intervention: Encapsulated K85, containing 85% eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA), or corn oil, both administered in a daily dose of 4 g for 12 weeks.

Main outcome measures: Change in metabolic and haemodynamic parameters related to intervention.

Results: Serum EPA and DHA increased significantly in the K85 group during the treatment period. The body-mass index remained unchanged. A 28% reduction in serum triglycerides was noted in the K85 group from the first 4 weeks. Total serum cholesterol was significantly reduced with both regimens. Serum high-density lipoprotein cholesterol increased significantly during the first 8 weeks in the K85 group. Significant reductions in systolic and diastolic blood pressures were noted in subjects on K85. The treatment did not affect serum glucose, plasma insulin and proinsulin levels. Insulin:glucose and proinsulin:glucose ratios remained unchanged.

Conclusions: The atherogenic risk profile was improved with K85 in subjects with combined hyperlipidaemia, but n-3 fatty acids supplementation did not affect glucose/insulin homeostasis.