The Effects of Supplemental Fish Oil on Blood Pressure and Morning Cortisol in Normotensive Adults: a Pilot Study

Abstract

PURPOSE: To determine the effects of 6wk of supplementation with fish oil (FO) on blood pressure and the morning salivary cortisol concentration in normotensive adults. METHODS: Testing was performed following an overnight fast. Subjects (n=40; 35+/-13y, mean+/-SD) rested supine for 40min, at which time blood pressure and heart rate were measured. Saliva was collected and analyzed for cortisol. Subjects were then randomly assigned to either: 4g/d of Safflower Oil (SO); or 4g/d of FO supplying 1,600mg/d eicosapentaenoic acid and 800mg/d docosahexaenoic acid. Testing was repeated following 6wk of treatment. RESULTS: Compared to SO, there was a significant decrease in systolic blood pressure with FO (SO=1.3+/-5.8 mmHg; FO=-6.8+/-10.2 mmHg; p=0.004), a significant reduction in pulse pressure (SO=0.2+/-7.8 mmHg; FO=-6.4+/-8.8 mmHg; p=0.02), and a tendency for a decrease in mean arterial pressure (SO=1.2+/-5.3 mmHg; FO=-2.5+/-7.3 mmHg; p=0.08). There was a tendency for salivary cortisol to decrease with FO (SO=0.005+/-0.129 µg/dL; FO=-0.068+/-0.148 µg/dL; p=0.072), however, this change was not significantly correlated with the change in systolic blood pressure (r=0.021, p=0.929). CONCLUSION: 6wk of supplementation with FO significantly decreases systolic blood pressure in normotensive adults and this change was not significantly correlated with a reduction in salivary cortisol.