Polyunsaturates and KCL to Control Mild Hypertension

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00000511
Recruitment Status : Completed
First Posted : October 28, 1999
Last Update Posted : December 13, 2013
National Heart, Lung, and Blood Institute (NHLBI)
Information provided by (Responsible Party):
Frank M. Sacks, Brigham and Women's Hospital

Brief Summary:
To test the efficacy of omega-3 fatty acids in untreated mild hypertensives and magnesium, calcium, and potassium supplementation supplementation in non-hypertensives. These clinical trials were conducted in sequence over a four year period.

Condition or disease Intervention/treatment Phase
Cardiovascular Diseases Heart Diseases Hypertension Vascular Diseases Dietary Supplement: mineral supplements Dietary Supplement: Trial 1: fatty acids, omega-3; Trial 2: Mineral supplements Behavioral: dietary supplements Phase 2

Detailed Description:


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.


Trial 1: Subjects were randomized to a fish oil treatment group of 6 or 12 grams/day of omega-3 fatty acids or to a placebo group. At the end of 12 and 24 weeks, participants in the three groups were crossed-over to one of the other two treatments for an additional 12 weeks. The primary outcome was clinic blood pressure on 3 days at the end of the treatment period.

Trial 2: Subjects were randomly assigned to one of four treatments and placebo: magnesium supplementation; potassium supplementation; calcium supplementation; all 3 supplements; matching placebos. The trial was double-blinded. Each of the treatments was administered for six months with measurements taken at baseline and at the end. The primary outcome was 24-hour ambulatory systolic BP.

The study completion date listed in this record was obtained from the Query/View/Report (QVR) System.

Study Type : Interventional  (Clinical Trial)
Allocation: Randomized
Intervention Model: Crossover Assignment
Primary Purpose: Treatment
Study Start Date : December 1983
Actual Primary Completion Date : November 1994
Actual Study Completion Date : November 1994

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Potassium

Arm Intervention/treatment
Placebo Comparator: Potassium, Magnesium, Calcium, The 3 together, Placebo
Parallel study design, 4 treatment groups
Dietary Supplement: mineral supplements
Dietary Supplement: Trial 1: fatty acids, omega-3; Trial 2: Mineral supplements
Behavioral: dietary supplements

Primary Outcome Measures :
  1. Blood Pressure [ Time Frame: End of study ]
    14 hour ambulatory BP

Information from the National Library of Medicine

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Ages Eligible for Study:   21 Years to 70 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Mild hypertensives, ages 21 to 70, with no evidence of end-organ damage.. Untreated hypertensives.

Responsible Party: Frank M. Sacks, Professor of Medicine, Brigham and Women's Hospital Identifier: NCT00000511     History of Changes
Other Study ID Numbers: 30
R01HL034593 ( U.S. NIH Grant/Contract )
R01HL034593-05 ( U.S. NIH Grant/Contract )
First Posted: October 28, 1999    Key Record Dates
Last Update Posted: December 13, 2013
Last Verified: December 2013

Additional relevant MeSH terms:
Cardiovascular Diseases
Heart Diseases
Vascular Diseases