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

Abstract

To determine the effects of 6wk of supplementation with fish oil (FO) on blood pressure and the morning salivary cortisol concentration in normotensive adults. 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. 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). 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.