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How Much Salt is Too Much?

 
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The standard nutrition labels you see on most packaged foods say your daily sodium intake should be less than 2,400 mg. A diet of average American food can easily contain much more sodium, mostly in the form of ordinary table salt. So how much is really too much?

One research group tested the effects of different salt concentrations in the body by measuring blood pressure after an intravenous infusion of 7,000 mg of sodium (in the form of NaCl, 18 g) for 378 healthy volunteers and 198 subjects with high blood pressure. This is 3 times the value recommended on our food labels. To get a baseline blood pressure, researchers then gave the test subjects a low sodium diet and a diuretic to flush out the salt.

For 26% of the healthy volunteers, the difference in blood pressure between high and low salt content was 10 mmHg or more. These were defined as salt sensitive. For the subjects with high blood pressure, 51% were found to be salt sensitive by this definition.

Salt sensitivity can also be defined in terms of the difference in blood pressure for the subject on a high salt diet (5,700 mg sodium per day) compared to low salt diet (200 mg sodium per day). For the overall population of adults who do not have high blood pressure, one third are reported to be salt sensitive. African Americans and elderly subjects are more likely to be salt sensitive than younger white adults.

Researchers in Japan identified a defect in kidney function as the cause of salt sensitivity. They suggest their findings may form the basis for development of drugs to treat this condition. However, for many people, an increase in dietary potassium is enough to suppress salt sensitivity.

Our kidneys work best with more potassium than sodium in our diets, according to researchers at the University of California. Potassium is abundant in fruits and vegetables, but not grains (bread, pasta, etc.) The average American diet may have more issues with potassium deficiency than with salt excess.

Dietary salt is a controversial subject. For a brief history of the debate, see https://www.empowher.com/media/reference/shaking-conventional-thinking-about-sodium-and-hypertension

Besides blood pressure, your sodium and potassium consumption can affect your risk for kidney stones. See https://www.empowher.com/news/herarticle/2009/08/17/diet-bones-and-kidney-stones

So if you love salt, you may not need to give it up. Talk to your doctor about how well your kidneys are taking care of your electrolyte balance.

by Linda Fugate, Ph.D.

References:

Katori M and Majima M, “A missing link between a high salt intake and blood pressure increase”, Journal of Pharmacological Sciences 2006; 100:370-390.

Morris, RC, et al., “Relationship and interaction between sodium and potassium”, Journal of the American College of Nutrition 2006; 25(3):262S-270S.

Add a Comment2 Comments

It can be quite a shock when you really look at labels and see how much sodium is in some packaged foods. Especially with sweet foods where you would not expect a lot of sodium to be hiding in the sugar.

It is important to note that CDC guidelines recommend a maximum daily sodium intake of 2,300mg. However, they suggest only 1,500mg for adults with high blood pressure, those aged over 40 years old, and all African American adults. So that is a lot of people (about 70%) who should really only have 1,500mg of sodium a day. That's tricky to do!

I did a review on the CDC guidelines early this year with suggestions of how to get down to 1,500mg of sodium a day. I hope it helps!
http://www.my-blood-pressure.com/lower-salt.html

September 3, 2009 - 1:53am
EmpowHER Guest
Anonymous

Very good article, thank you! A sentence got my attention: "The average American diet may have more issues with potassium deficiency than with salt excess". It is already hard to raise awareness to consume less sodium in the U.S. considering how much people eat out or eat processed foods in the country. Raising awareness for consuming more potassium might be even harder!
Thanks again for the article.
Umit Demir
Eatlowsodium.com Owner

September 2, 2009 - 1:44pm
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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.

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