Effects of Fish Oil Supplementation on Markers of the Metabolic Syndrome

Objective To investigate whether fish oil affects cardiovascular risk factors during the adolescent growth spurt. Study design A total of 78 boys age 13-15 years with a mean body fat percentage of 30% +/- 9% were randomly assigned to consume fish oil (providing 1.5 g of n-3 long-chain polyunsaturated fatty acid/day) or vegetable oil (control) for 16 weeks. The oils were included in bread. Results After the intervention, the red blood cell (RBC) content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were 1.2% +/- 0.5% and 6.7% +/- 1.6%, respectively, in the those receiving fish oil (FO group), compared with 0.6% +/- 0.3% and 4.1% +/- 0.9% in the control group. Systolic blood pressure (SBP) was 3.8 +/- 1.4 mm Hg lower (P<.006) and diastolic blood pressure (DBP) was 2.6 +/- 1.1 mm Hg lower (P<.01) in the FO group compared with the control group. Plasma triacylglycerol (TAG) concentration and insulin sensitivity were unaffected by either of the treatments. Plasma high-density lipoprotein (HDL) and non-HDL cholesterol were increased by 5% and 7%, respectively, in the FO group, and by 2% and 0% in the control group (P<.01-.02). The changes in RBC EPA content were inversely correlated with the changes in SBP and DBP and directly correlated with the increases in HDL cholesterol and non-HDL cholesterol concentrations. No association was seen between RBC EPA and plasma TAG concentration or insulin sensitivity. Conclusion Fish oil improves BP in normotensive and normolipidemic slightly overweight adolescent boys. (J Pediatr 2010; 157: 395-400).