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.