Salt - The Non-essential Non-nutrient

By Don Matesz

Many people have been convinced that salt – sodium chloride – is important in the diet.  

Some people have written books to convince people to consume more salt.  James DiNicolantonio, for example: 

But do you really need mineral salt in your diet?  

No.  There is no dietary requirement for salt apart from food.  The Yanomami tribe of South America never uses salt on or in food.  They show no signs of either sodium or chloride deficiency.  

Salt was once so scarce that it was used as money.  Our word "salary" comes from a time when Roman soldiers were paid with wages of salt.  The high value and scarcity of salt meant that most people did not use it in food, except perhaps for those who were wealthy.  Our modern high salt intake is a consequence of modern salt extraction techniques.  

The Food and Nutrition Board of the National Academies of the U.S. states that dietary sodium deficiency does not normally occur in man regardless of salt intake:

They estimate the true obligatory daily losses and therefore true minimum sodium requirement under maximum adaptation to be about 115 mg per day, and then quadruple that to estimate that 500 mg daily would cover sodium needs under almost all conditions.
Notably they never cite any evidence for a true sodium requirement.  Instead, they talk about "sodium balance" by which they mean the amount of sodium intake required to replace what is lost in urine, sweat and feces.  In their words:

"In a temperate climate, the healthy adult can maintain sodium balance with a very low intake of sodium."

Losses by these routes will always be proportional to intake:  more in means more out, less in means less out.  They have no proof of any absolute sodium requirement.  

They make similar statements about chloride: "Under normal circumstances, dietary deficiency of chloride does not occur."

 For example "evidence" of dietary sodium and chloride deficiency they cite for example this study of infants fed an artificial formula Neo-Mull-Soy:

This is suspect simply because Neo-Mull-Soy is an industrial product substituted for God-given human mother's milk.  Note that they say that the outstanding laboratory features were severe hypokalemic metabolic alkalosis, low urinary chloride concentrations, and erythrocytopenia.  Severe hypokalemia means low (hypo-) potassium (kal-) in blood (-emia).   Loss of appetite (anorexia), failure to thrive, muscle weakness, and lethargy are all symptoms of potassium deficiency:

The fact that this condition resolved by supplementing either sodium chloride or potassium chloride does not prove that the condition was caused by chloride deficiency.  Since sodium and potassium ions have similar +1 electrical charges, sodium can substitute for potassium to some extent.  

Since the authors did not isolate chloride supplementation, they did not prove that the condition was caused by chloride deficiency.  They noted very low potassium in the blood, and symptoms consistent with potassium deficiency, and provided supplements of either sodium or potassium that could provide some relief from such deficiency.  They did not prove a chloride deficiency syndrome.  They did not prove that chloride is essential in the diet.  It may be, in some very small amount, like iodide, but this report provides no evidence.

So far, we know potassium is essential; and have no strong evidence that either sodium or chloride is essential, but we know that people on salt-free diets have no signs of either sodium or chloride deficiency. Instead, they (exemplified by the Yanomami) have life-long low blood pressure and a high immunity to cardiovascular and other degenerative diseases common among people eating salted diets.

Here are the sodium and potassium contents of commonly consumed animal products:  

Note that human mothers' milk provides 3 times as much potassium as sodium.  This ratio or greater is found in cow milk, beef, lamb, chicken and cod.  We can safely assume that this is the baseline optimal dietary K:Na ratio for humans of all ages because it is the ratio consumed by infants as well as any hypercarnivore.  We should get at least 3 times as much potassium as sodium.  The foods have the optimal ratio as they are; adding salt to them will only reduce the ratio.

Here's an hypothetical 1600 kcal menu with the sodium and potassium contents:

You can see that without adding any salt whatsoever, the sodium content far exceeds the estimated true minimum of 115 mg required to prevent negative sodium balance, and exceeds by 50% the guesstimated 500 mg that would cover all common circumstances.  In other words, it already has excess sodium; adding salt only increases the excess.  Meanwhile the potassium is safely above the estimated minimum requirement of 1600-2000 mg.

However, as stated directly above, potassium is less well conserved that sodium, and there is considerable evidence that dietary potassium exerts a beneficial effect in hypertension, cardiovascular diseases, kidney disease, bone density, and glucose regulation (diabetes) .

I personally would aim for a higher ratio of potassium to sodium if you have any of the above conditions, want to prevent any of those conditions, or want to maximize health and performance.