Low Salt Diet

Low salt diet and the importance of potassium

Salt (or dietary sodium) is now typecast as the villain in the high blood pressure saga. This is a bit unfair because without sodium, there would be no life. Sodium is one of the essential basic constituents of our bodies and is central to most processes that sustain life and is present in very single cell of our bodies and in every drop of blood.

Potassium plays an important role too, and probably we should talk more about potassium, or at least remember it when we talk about a low salt diet because there is an important relationship between the two and their effects upon blood pressure. A review in the prestigious scientific journal, the New England Journal of Medicine stated the following:

“Recent evidence as well as classic studies point to the interaction of sodium and potassium, as compared with an isolated surfeit of sodium or deficit of potassium, as the dominant environmental factor in the pathogenesis of primary hypertension and its associated cardiovascular risk”.

(Horacio J. Adrogué, M.D., and Nicolaos E. Madias, M.D. N Engl J Med 2007; 356:1966-1978)

The modern diet

The problem with the modern diet, particularly in advanced countries, is that they contain way too much sodium and not enough potassium - a low salt diet needs to reverse this.

The main culprit is today’s industrialized food processing methods. It is estimated that 12% of dietary sodium chloride originates naturally in foods, whereas approximately 80% is the result of food processing, and the rest is what we add in cooking or from the salt cellar.

Like many problems caused by modern living, scientists think that how our bodies evolved to cope with conditions centuries ago is now working against us. Because salt was so essential to life and yet low in foods available naturally (the reverse being true for potassium) our kidneys evolved to conserve salt and get rid of potassium. Now that modern foods have reversed the dietary balance, our kidneys sometimes keep back too mush salt and let go too much potassium.

We must therefore pay more attention to the balance of sodium and potassium when considering a low salt diet. Potassium depletion plays a significant role in hypertension. Dietary potassium helps keep blood pressure down both by its direct effects and by reducing the bad effects of sodium.

It is important to note that potassium in the diet, as we have it in fruit and vegetables, is more effective than supplements which often contain potassium with chloride which reduces its anti-hypertensive effect. (see reference here).

So in summary what the science tells us is that a low salt diet should be low in sodium and also high in potassium - preferably from fruit and vegetables).

How does sodium raise blood pressure?

People are often curious as to why sodium raises blood pressure – what does it do?

There appear to be two main effects of sodium in raising blood pressure. First, sodium has an effect on increasing water retention in the body – this expands the circulating amount of blood in the body, raising blood pressure. Secondly, it has an effect of reducing the ability of blood vessels to relax. If you remember, one of the mechanisms by which blood pressure can be reduced is by relaxation of blood vessels.

There are other somewhat more complex interactions that form part of the story but that is beyond our scope here.

How to reduce sodium in the diet

U.S. guidelines call for less than 2,300 mg of sodium per day, and anyone with high blood pressure should take no more than 1,500 mg per day as should anyone who is likely to be salt sensitive, which includes African –Americans.

Here are some tips to help with your low sodium diet:

• Eat more fresh food – prepared at home.

• Do not add salt at the table

• Avoid foods high in sodium - the following are some of the worst culprits:

Frozen meals These can contain a quarter or more of your total daily requirement of 2300 mg.

Cereals Canned Foods & soups Because they are made to last they are high in preservatives, and often have salty sauces. Avoid these or look for ‘no salt added versions’.

Preserved Meats These are loaded with sodium. The amounts vary – you will need to read the label. If in doubt – leave it out.

Flavorings Worcester sauce, ketchup, spaghetti sauce, soy sauce all have high salt levels.

Start going for healthier flavours that can give food an interest such as lemon juice, vinegar, herbs and spices. You can experiment with more exotic and healthy fruit based marinades etc. Beware though, some spices or canned products may defeat your objective so check.

Salty Snacks Potato chips/crisps, pretzels, peanuts are more often than not salted for flavor and will contribute a hefty portion of your daily ration of sodium.

Pre-Packaged foods Avoid foods that appear healthy but come with packet of flavoring. Invariably this contains sodium.

Eat out with care If you like eating out, there is no need to give it up. You will need to find a few favored restaurants where the chef knows how to do low sodium dishes or who will prepare according to your needs, using less salt and ensuring that fresh rather than processed ingredients are used.

Importantly you will need to learn to read labels and stick to foods that are lower in sodium.

    Key points

  • A high potassium, low salt diet is the cornerstone of a blood pressure-friendly diet and is effective in lowering blood pressure in people with high blood pressure.
  • If you understand the basic principles, you will be able to create your own low salt diet version of just about all your favorite meals, or at least find suitable substitutes.

  • The main source of sodium in the diet is not the salt cellar or the natural salt content of foods but the processing methods used these days.
  • Eating food prepared from fresh ingredients cooked at home is therefore the most effective way to reduce your sodium intake.
  • Shop wisely and use the labels on food to guide you. You should aim for a daily intake of no more than 1500mg.
  • Start slowly and reduce your intake gradually.

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This page was last modified on : May 11, 2011.