Report #6569 7/30/95
If you have high blood pressure, the odds are that restricting salt
will lower your blood pressure only a minuscule amount. However,
excessive salt intake may cause osteoporosis or a weakening of
The theory is sound. The evidence is weak. The theory is that when
you take in more salt than you need, the extra salt causes your body
to hold more water which enlarges your blood volume and raises your
blood pressure. However, the vast majority of Americans will not
have their blood pressure rise after taking extra salt (1) and salt
restriction does not lower blood pressure in people with normal
blood pressure and it reduces blood pressure in people with high
blood pressure only a minuscule amount. (2,3,4) On the other hand,
low- fat diets and weight reduction lower high blood pressure to
normal in most patients. (5)
However, when you take in more salt than you need, urine levels of
hydroxyproline rise considerably, showing that bone is being broken
down./ Increasing salt intake increases calcium loss in the urine.
(6) Ingesting large amounts of salt also is associated with an
increased risk of stomach cancer.(6)
Severely restricting salt intake by eating only low-salt foods can
harm you by raising blood pressure. (7) and the bad LDL cholesterol
in your bloodstream. (8,9). Salt deficiency causes your kidneys and
adrenal glands to produce large amounts of the hormones, renin and
aldosterone, which raise blood pressure. It is all right to stop
adding salt to your food and cooking, but it is not reasonable to
try to treat high blood pressure by seeking out and eating only
foods that contain very little salt. If you have high blood
pressure, lose weight if you are overweight. Most doctors will
recommend salt restriction.
By Gabe Mirkin, M.D., for CBS Radio News
1) Science 1982(April);216(2):38-40.
2) 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.
3) 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
4) JD Swales. Salt and blood pressure revisited. Journal of Human
Hypertension 9: 6 (JUN 1995):517-5214.
5) Wt and dietary fat more important. Hypertension 1991;
6) TFT Antonios, GA Macgregor. Salt intake: Potential deleterious
effects excluding blood pressure. Journal of Human Hypertension 9:
6 (JUN 1995): 511-515.
7) 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.
8) severe sodium restriction raises LDL. Klin Wochenschrift 1990;
68:664-668. 9) Klin Wochenschrift 1991 69 suppl):51-576383.