THE EFFECT OF FISH-OIL ON BLOOD-PRESSURE AND HIGH-DENSITY LIPOPROTEIN-CHOLESTEROL LEVELS IN PHASE-I OF THE TRIALS OF HYPERTENSION PREVENTION

Objective: To study the effects of moderate doses of fish oil on blood pressure and high-density lipoprotein (HDL)-cholesterol. Methods The participants were 350 normotensive men and women aged 30-54 years who were enrolled from seven academic medical centers in phase I of the Tr ials of Hypertension Prevention. They were randomly assigned to receiv e placebo or 6 g purified fish oil once a day, which supplied 3 g n-3 polyunsaturated fatty acids for 6 months. Results: Baseline blood pres sure was (mean+/-SD) 123 +/- 9/81 +/- 5 mmHg. The mean differences in the blood pressure changes between the fish oil and placebo groups wer e not statistically significant. There was no tendency for fish oil to reduce blood pressure more in subjects with baseline blood pressures in the upper versus the lower quartile (132/87 versus 114/75 mmHg), lo w habitual fish consumption (0.4 versus 2.9 times a week) or low basel ine plasma levels of n-3 fatty acids. Fish oil increased HDL(2)-choles terol significantly compared with the placebo group. Subgroup analysis showed this effect to be significant in the women but not in the men. Increases in serum phospholipid n-3 fatty acids were significantly co rrelated with increases in HDL(2)-cholesterol and decreases in systoli c blood pressure. Conclusion: Moderate amounts of fish oil (6 g/day) a re unlikely to lower blood pressure in normotensive persons, but may i ncrease HDL(2)-cholesterol, particularly in women.