Polyunsaturates and KCL to Control Mild Hypertension

BACKGROUND:

The hypothesis that omega-3 fatty acids as well as magnesium and potassium in the diet lowered blood pressure in mild hypertensives needed further documentation, although preliminary and less well controlled studies had suggested such an effect was possible. In a previous study the investigators did not find a hypotensive effect of another polyunsaturated fatty acid, linoleic acid. In addition, findings of lower blood pressures in vegetarians and results obtained from a study in which vegetarian diets were fed to normotensives led to the conclusion that dietary factors other then linoleic acid were responsible for the possible hypotensive effect of vegetarian diets. The nutrients which were selected for further study, omega-3 fatty acids, magnesium and potassium, occur in higher amounts in vegetarian diets.

Dietary supplementation with fish oils had only been done in a few studies with inconclusive results. However, the relationship of omega-3 fatty acids to the synthesis of prostacyclins, which are locally active vasodilators and which decrease with the excretion of the vasoconstrictor thromboxane, provide a possible mechanism for an effect of these compounds on blood pressure.

The role of potassium in the control of blood pressure was first suggested from cross-cultural studies in which populations consuming high levels of potassium displayed lower rates of hypertension and a decrease in blood pressure with age. Cohort studies within this country have also shown a relationship between potassium intake or the ratio of potassium and sodium, as measured by urinary excretion and blood pressure. Most constantly it found that blood pressure differences between blacks and whites have been related to differences in potassium excretion.

The results from human experimental studies involving potassium supplementation in normotensives and hypertensives have indicated mixed effects but blood pressure lowering was most consistently observed in subgroups with a family history of hypertension or those with higher blood pressure.