SALT AND HIGH BLOOD PRESSURE
Report #6608 8/19/95
It is not reasonable to treat high blood pressure only with severe salt restriction. People with high blood pressure should eat a low-fat diet and lose weight if overweight.
Excess salt intake can raise blood pressure slightly and damage the kidneys of people (1) who already have high blood pressure and it can also cause osteoporosis, (2) and increase stomach acidity. (2) However, the vast majority of Americans will not have their blood pressure rise after taking extra salt (3) and salt restriction reduces blood pressure in people with high blood pressure only a minuscule amount. (4,5,6) On the other hand, low-fat diets and weight reduction lower high blood pressure to normal in most patients. (7) Most doctors feel that it is perfectly healthful for people with high blood pressure or fluid retention to avoid adding extra salt by not adding salt to food, not cooking with salt and avoiding salty tasting foods, but it is not reasonable for the vast majority to severely restrict salt by avoiding all foods that contain significant amounts of salt or taking diuretics at the same time that they are on a low-salt diet. Severe salt restriction is associated with an increased risk of developing a heart attack (8). Easting only very low-salt foods can harm you by raising blood pressure. (9) and the bad LDL cholesterol in your bloodstream. (10,11). Salt deficiency causes your kidneys and adrenal glands to produce large amounts of the hormones, renin and aldosterone, which raise blood pressure. Most doctors will recommend salt restriction.
By Gabe Mirkin, M.D., for CBS Radio News
1) MR Weir, DR Dengel, MT Behrens, AP Goldberg. Salt-induced increases in systolic blood
pressure affect renal hemodynamics and proteinuria. Hypertension 25: 6 (JUN
1995):1339-1344.
2) TFT Antonios, GA Macgregor. Salt intake: Potential deleterious effects excluding
blood pressure. Journal of Human Hypertension 9: 6 (JUN 1995): 511-515.
3) Science 1982(April);216(2):38-40.
4) Silman AJ, Locke C, Mitchel P. Humpherson P. Evaluation of the effectiveness of a
low- sodium diet in the treatment of mild to moderate hypertension. Lancet 1983(May
28):1179.
5) BR Davis, A Oberman, MD Blaufox, S Wassertheilsmoller, N Zimbaldi, K Kirchner, J
Wylierosett, HG Langford. Lack of effectiveness of a low-sodium high-potassium diet in
reducing antihypertensive medication requirements in overweight persons with mild
hypertension. American Journal of Hypertension 1994(Oct);7(10 Part 1):926-932. This study
provides no support for the sole use of a low-sodium/high-potassium diet as a practical
therapeutic strategy in maintaining blood pressure control in the moderately obese.
6) JD Swales. Salt and blood pressure revisited. Journal of Human Hypertension 9: 6 (JUN
1995):517-5214.
7) Wt and dietary fat more important. Hypertension 1991;18(suppl 1):115-120.
8) MH Alderman, S Madhavan, H Cohen, JE Sealey, JH Laragh. Low urinary sodium is
associated with greater risk of myocardial infarction among treated hypertensive men.
Hypertension 25: 6 (JUN 1995):1144-1152.
9) M Egan, K. Stepniakowski, TL Goodfriend Renin and aldosterone are higher and the
hyperinsulinemic effect of salt restriction greater in subjects with risk factors
clustering. American Journal of Hypertension 7: 10 Part 1:OCT 1994:886-893. Greater
activation of the renin-aldosterone axis may contribute to the rise of blood pressure and
the larger increase of insulin during marked salt restriction in the high compared to low
risk subjects. These findings may partially explain the variable effects of salt
restriction on insulin levels in different studies.
10) severe sodium restriction raises LDL. Klin Wochenschrift 1990;68:664-668. 11) Klin Wochenschrift 1991 69 suppl):51-57.