Blood pressure-lowering effect of mackerel diet.

Several dietary studies were designed to evaluate the blood pressure-lowering effect of long-chain n-3 polyunsaturated fatty acids (PUFA) under similar experimental conditions. In the first 3 studies, 15 normotensive volunteers, 14 patients with mild essential hypertension and 15 patients with hyperlipoproteinemias (HLP, phenotypes IIa, IIb, IV and V), respectively, were put on isocaloric diets supplemented either with 2 cans/day of commercially available mackerel fillet in tomato pulp for 2 weeks or with 2 cans/day of herring fillet in tomato pulp for 2 weeks in a crossover regimen. Besides a significant fall of serum cholesterol and triglycerides systolic as well as diastolic blood pressure (BP) from normotensive subjects and systolic blood pressure from mildly hypertensive and hyperlipemic patients was significantly decreased at the end of the mackerel diet providing the twofold higher dose of long-chain n-3 PUFA. Plasma noradrenaline and thromboxane B2 were likewise depressed, the former in normotensive volunteers, the latter in mildly hypertensive patients. In hyperlipemics with an initial systolic BP of 160 mmHg and above the hypotensive effect appeared more pronounced as compared to hyperlipemics with systolic blood pressure below 160 mmHg. In a fourth (long-term) study providing as low as 3 cans/week of mackerel for 8 months systolic and diastolic BP of 12 male patients with mild essential hypertension appeared significantly reduced at the end of the dietary period. This indicates that even a low-dose regimen might effectively lower mildly elevated blood pressure over a long-term period.(ABSTRACT TRUNCATED AT 250 WORDS)