HEMODYNAMIC AND NEUROHUMORAL EFFECTS OF FISH-OIL IN HYPERTENSIVE PATIENTS

Recent studies showed that supplementation of a large dose of fish oil is effective in lowering blood pressure. Whether supplementation of a low dose of fish oil is also effective in lowering blood pressure is controversial. The present study evaluates the hemodynamic and humoral effects of low-dose dietary fish oil supplementation in patients with mild hypertension. Eleven patients with mild hypertension were given 3 g/day of n-3 polyunsaturated fatty acids for 6 week. Twenty-four hou r blood pressure monitoring and humoral parameters were recorded befor e and during fish oil treatment. In five patients, blood pressure resp onse to angiotensin II (AII) infusion (1, 2, 3, 6, 9 ng/kg/min) was al so recorded before and during treatment. Casual mean arterial pressure was unchanged (111+/-1 mm Hg v 109+/-3 mm Hg; P=NS). Average 24-h mea n arterial pressure (MAP) also did not change during fish oil treatmen t (98+/-2 mm Hg v 99+/-3 mm Hg; P=NS). Fish oil supplementation did no t attenuate the vascular reactivity to AII infusion. Maximal MAP follo wing All infusion (9 ng/kg/min) was 128+/-5 mm Hg before and 129+/-7 m m Hg during fish oil treatment (P=NS). Plasma levels of norepinephrine , renin activity, aldosterone, and atrial natriuretic peptide remained unchanged during treatment. Plasma levels of total cholesterol slight ly increased from 200+/-10 mg/dL to 211+/-9 mg/dL (P<.05), but plasma levels of high-density lipoprotein (HDL) cholesterol, low-density lipo protein (LDL) cholesterol, and triglycerides were unaffected. A low do se of fish oil supplementation failed to lower MAP and did not attenua te the pressure increase following AII infusion. Thus, the use of low- dose fish oil as an antihypertensive agent should be reconsidered.