Many studies confirm that regular consumption of fish and fish oil contributes to a drop in blood pressure. This effect goes along with the prevention of artherosclerosis and the reduction of triglyceride levels. Reportedly, the reduction is dose-dependent -- that is, the more you take, the greater the effect you're likely to see. Even with robust supplementation, the decrease will probably be a modest one, though. People with elevated blood pressure may see a more significant drop. Blood pressure in the normal range has been found unaffected by fish oil [source: Morris, Sacks and Rosner].
Combining supplementation with other dietary changes may enhance the effect on blood pressure. In an Australian study, overweight patients who dieted (that is, restricted their caloric intake) while taking fish oil saw a drop in blood pressure. This group also enjoyed a 38 percent reduction in triglycerides and a 24 percent increase in HDL or "good" cholesterol [source: Mori, et al.].
High blood pressure is a concern for many heart transplant patients. In one study, doctors at the University of Oslo treated several heart transplant recipients with fish oil, and found it an effective means of preventing the hypertension that frequently accompanies the heart transplant process [source: Holm, et al.].
Bear in mind that taking fish oil, especially in higher dosages, can bring with it an increased risk of bleeding. If you are already on medication to lower your blood pressure or reduce coagulation, consult your physician before taking fish oil supplements. To learn more about fish oil, visit the links on the following page.