1. ¹Research Department of Human Nutrition, The Royal Veterinaryand Agricultural University, Frederiksberg, Denmark
2. ²Steno Diabetes Center, Gentofte, Denmark
3. ³Department of Biochemistry and Nutrition, The Technical University of Denmark, Lyngby, Denmark
4. ⁴Danish Veterinary and Food Administration, Department of Food Safety and Toxicology, Division of Biochemical and Molecular Toxicology, Søborg, Denmark

Correspondence: H Pedersen, Food Biotechnology and Engineering Group, The Technical University of Denmark, Søltoftsplads, 2800 Kgs. Lyngby, Denmark. E-mail: hep@biocentrum.dtu.dk

Guarantor: Peter Marckmann.

Contributors: Helle Pederson, Martin Petersen, Artheline Major-Pedersen, Tonny Jensen, Søren Lauridsen, Nina Skall Nielsen.

Received 18 January 2002; Revised 22 July 2002; Accepted 24 July 2002.

Abstract

Objective: Fish oil supplement has been proposed as a non-pharmacological strategy to correct the atherogenic lipid profile associated with type 2 diabetes mellitus. However, fish oil may have deleterious effects on lipid peroxidation and glycemic control.

Design: In this study, 44 type 2 diabetic patients were randomized to vitamin E standardized (53.6 mg/day) supplementation (capsules) with 4 g daily of either fish oil (n=23) or corn oil (n=21) for 8 weeks preceded by a 4 week run-in period of corn oil supplementation. LDL was isolated by density gradient ultracentrifugation and oxidized in vitro with Cu²⁺. As a marker of in vivo oxidation malondialdehyde concentration in LDL (LDL-MDA) was measured.

Results: Fish oil reduced both mean lag time (before, 57.8; after, 48.8 min, P<0.001) and mean propagation rate (before, 0.018 OD/min; after, 0.015 OD/min, P<0.001), whereas corn oil had no influence on lag time and propagation rate. The changes in lag time and propagation rate differed significantly between fish oil and corn oil treatment. LDL-MDA changes differed borderline significantly between groups (FO, 110.4 pmol/mg protein; CO, 6.7 pmol/mg protein; P=0.057). Fish oil supplementation had no influence on glycemic control as assessed from HbA_1c and fasting blood glucose.

Conclusion: According to our findings, fish oil supplementation leads to increased in vivo oxidation and increased in vitro oxidation susceptibility of LDL particles. More studies are needed to clarify the clinical importance of this finding.

Sponsorship: Financially supported by The Danish Heart Association and Dansk Droge A/S. Dansk Droge A/S generously provided the fish oil and corn oil capsules.