Salt Scare

By 1982, salt was called ‘A New Villain’ on the cover of TIME magazine. The 1988 publication of the INTERSALT study seemed to seal the deal. This massive study involved 52 centers in 32 countries and laboriously measured salt intake and compared this to blood pressure. Across all populations, the higher the salt consumption, the higher the blood pressure. Seemed like a slam dunk, although the effect was quite small. A 59% reduction in sodium intake would be predicted to lower the blood pressure by only 2 mmHG. If your systolic blood pressure was 140, severely restricting your salt could lower that to 138. However, no data existed as to whether this would translate into less heart attacks and strokes. But based on this influential study, in 1994 the mandatory Nutrition Facts Label proclaimed that Americans should only eat 2,400 mg per day (about one teaspoon of salt). Yet the stubborn fact remains that virtually every healthy population in the world eats salt at levels far above that recommendation. The dramatic improvements in health and lifespan of the last 50 years have occurred during a period where almost everybody was considered to be eating too much salt.

Our belief in the benefits of low salt consumption are largely based on mis-information and myth-information. The underlying assumption of the salt reduction advice is that eating too much salt is a recent phenomenon brought on by the increased consumption of processed foods. Dahl, for example, claimed in his writings that widespread use of salt as a condiment was uncommon until modern times.

Data from military archives going back to the war of 1812 show that soldiers and presumable the rest of Western society ate between 16 and 20 grams of salt per day. During the war of 1812, soldiers maintained a daily consumption of 18g/ day despite high cost. American prisoners of war complained bitterly that their 9 g/day of salt was ‘scanty and meager’. It was only after World War II, when refrigeration replaced salting as the primary means of preserving food that Americans lowered their average salt intake to 9g/ day where it has remained since. During that period pre-WWII, there was no concern of excess deaths from heart disease, stroke or kidney disease – the main things used to scare us into lowering our salt intake.

The Tides Turn

From its very inception, there were problems with the hypothesis that lowering salt could save lives. Dahl failed to notice all the various high-salt eating cultures that had no adverse health consequences. The Samburu warriors, consume close to two teaspoons of salt per day even going as far as eating salt directly from the salt licks meant for their cattle. Despite eating all this salt, the average blood pressure is just 106/72 mmHg and does not rise with age. In comparison, about one-third of the adult population in America is hypertensive with a blood pressure of at least 140/90 mmHg or higher. For reference, a normal blood pressure is less than 120/80 mmHg and generally rises with age in the United States.Villagers from Kotyang, Nepal, eat two teaspoons of salt per day, and the Kuna Indians eat one and a half teaspoons of salt per day, with no hypertension words, clearly contradicting Dahl’s hypothesis that a high-salt diet causes hypertension.

The most recent survey of global salt intake shows that no area of the world conformed to either the AHA or the WHO recommendations for salt restriction. The central Asian region had the highest salt intake, followed closely by high income Asia Pacific region including Japan and Singapore. The Japanese diet is notoriously high in sodium with copious use of soy sauce, miso and pickled vegetables. The Japanese themselves seem to suffer no ill effect as they have the world’s longest life expectancy at 83.7 years. Singapore is third in life expectancy at 83.1 years. If eating salt was really so bad for health, how could the world’s longest lived people also eat one of the world’s saltiest diets?

The concerns of a low salt diet started in 1973, when an analysis found six where the average blood pressure was low despite a high-salt diet. For example, the Okayuma, consumed more salt than most nations today (up to 3 1/3 tsp per day), and yet had some of the lowest average blood pressures in the world.

In some cases, blood pressure actually decreased as salt intake increased.  For example, North Indians consumed an,average salt intake of 2 ½ tsp per day (14 grams) or but maintained a normal blood pressure of 133/81 mmHg.  In South India, average salt intake was about half that of North India, but the average blood pressure was significantly higher at 141/88 mmHg.      

But there was still the question of the massive INTERSALT study. Further analysis of the data began to paint a significantly different picture of salt. Four primitive populations (the Yanomamo, Xingu, the Papua New Guinean, and the Kenyan) had been included in the initial analysis, which had significantly lower sodium intakes than the rest of the world. They lived a vastly different, primitive lifestyle from the others, and one had a sodium intake 99% lower than the rest. These outliers had limited generalizability to the rest of the world and because they were such outliers, had an outsized effect on the averages.

These 4 primitive societies differed from modern ones in far more than just diet. For example, the Yanomamo Indians of Brazil still live traditionally, hunting and gathering just as they had done centuries ago. They practice endocannibalism, where the ashes of loved ones are consumed because they believe it keeps them alive. There is no processed foods. There is no modern medicine. Comparing this tribe living in the forests of the Amazon to a modern American in the forests of New York is hardly fair. Isolating a single component of their diet, sodium and proclaiming it to be solely responsible for high blood pressure is the height of bad research. It is no different than concluding that wearing loincloths lowers your blood pressure.

There were other issues, too. Two populations (Yanomamo and Xingu Indians), when studied further, had the near absence of a specific gene D/D of the angiotensin converting enzyme, which put these populations at extremely low risk of heart disease and hypertension. Thus, low sodium intake may not be the major or even minor contributor to low blood pressure in these groups.

In this case, more information can be gained by removing these outliers from the study populations and seeing if the original salt hypothesis holds true. When those four primitive populations were removed and forty-eight Westernized populations were left in the study, the results were completely opposite the original findings.  Blood pressure actually decreased as salt intake increased. Eating less salt was not healthy, it was harmful.

The evidence from the United States was not encouraging either. The National Health and Nutrition Examination Survey (NHANES) are large scale surveys of American dietary habits carried out periodically. The first survey found that those eating the least salt died at a rate 18% higher than those eating the most salt. This was a highly significant, and disturbing result.

The second NHANES survey confirmed that a low salt diet was associated with a staggering 15.4% increased risk of death. Other trials found an increased risk of heart attacks of eating a low salt diet in treated hypertensive patients. Those were precisely the patients doctors had been recommending a low salt diet!

In 2003, worried, the Center for Disease Control, part of the US Department of Health and Human Services asked the Institute of Medicine (IOM) to take a fresh look at the available evidence focusing not on blood pressure, but mortality and heart disease

After an exhaustive search of the medical literature, the IOM made several major conclusions. Although low salt diets could lower blood pressure, “Existing evidence, however, does not support either a positive or negative effect of lowering sodium intake to <2300 mg/d in terms of cardiovascular risk or mortality in the general population.”. That is, lowering the salt intake did not reduce risk of heart attack or death.

However, in heart failure, “The committee concluded that there is sufficient evidence to suggest a negative effect of low sodium intakes”. Oh my. The very patients we were most strenuously recommending to reduce their salt would be harmed the most.

But dogma is hard to change. The 2015 Dietary Guidelines continues to recommend reducing sodium intake  to less than 2,300 mg of sodium (about one teaspoon of salt) per day with a recommendation of no more than 1,500 mg of sodium (about two-thirds of a teaspoon of salt) per day in hypertensives, blacks, and middle-aged and older adults.

Why is salt restriction dangerous?

Salt is crucial to maintain an adequate blood volume and blood pressure ensuring that our tissues are perfused with the oxygen carrying blood and nutrients.  Salt is composed of equal parts sodium and chloride. When we measure the electrolytes in the blood, salt (sodium and chloride) are by far and away the most common ions. For example, normal blood will contain sodium at a concentration of approximately 140 mmol/L, and chloride at 100 mmol/L, compared to potassium at 4 mmol/L and calcium at 2.2 mmol/L. No wonder we need salt so badly.

There is speculation as to the evolutionary reasons why our blood evolved to be mostly salt. Some believe that we evolved from single celled organisms in the ancient seas of the Earth. As we developed multicellularity and moved onto land, we needed to carry some of the ocean with us as ‘salt water’ inside our veins and hence salt comprises the vast majority of the electrolytes of the blood. Salt is vital, not a villain.

2018-09-25T09:47:36+00:0016 Comments

About the Author:

Dr. Fung is a Toronto based kidney specialist, having graduated from the University of Toronto and finishing his medical specialty at the University of California, Los Angeles in 2001. He is the author of the bestsellers ‘The Obesity Code’ and ‘The Complete Guide to Fasting’. He has pioneered the use of therapeutic fasting for weight loss and type 2 diabetes reversal in his IDM clinic.

16
Leave a Reply

avatar
9 Comment threads
7 Thread replies
1 Followers
 
Most reacted comment
Hottest comment thread
13 Comment authors
Gage HastingsGage HastingsJean JohnsonMonicaLucy Recent comment authors
  Subscribe  
newest oldest most voted
Notify of
Anthony
Guest
Anthony

When I am on IF or EF, my blood pressure sometimes rises above normal and i experience heart palpitations. Is this related to the loss of sodium n chlorine that foms the major electrolytes in our body?

Gage Hastings
Guest
Gage Hastings

It could be partly due to the raised adrenalin levels during a fast as well as low sodium, magnesium and potassium. Magnesium is especially important. Go on the web and look up how to make magnesium water. Magnesium is necessary for your musles to be able to relax and it also affects the walls of your arteries and veins, allowing them to relax. Low magnesium will also raise insulin resistance.

BobM
Guest
BobM

Anthony, it might be. Even on fasts of 22 hours, I take in salt. I’ve been putting salt under my tongue or drinking pickle juice (high in salt). I will also add a bit of salt to my (black) coffee or (plain) tea. For longer fasts, I take salt daily and consider taking magnesium and potassium if anything deleterious (eg, brain fog, cramps) shows up. I have been tracking my blood pressure for over 5 years. I have over 1,500 blood pressure samples in that time. I started increasing my salt intake a while ago. I can’t tell a difference… Read more »

Anthony
Guest
Anthony

Tks BobM, will start with salt and observe if the frequencies lessens

Mary
Guest
Mary

I have been increasing my salt intake and have seen my BP begin in stabilize (123/78 average). I exercise everyday except Sunday – using that as a day of rest except for a morning walk with the dog I have tried to incorporate IF into my Keto regime. Unfortunately, I an getting early morning headaches x 2 weeks (usually at 12 hour mark of last meal). My BS is usually around 90-100 (average 94) and Blood Ketone average is 1.8-2.2 in the a.m. upon rising. I am not sure where the headaches are coming from. I have tried going heavy… Read more »

JohnM
Guest
JohnM

I get an early morning headache every time I eat something sweet within a few hours of bed. It can be something as simple and seemingly innocent as a few grapes or fresh strawberries. Substitute a small piece of cheese; no headache.

Forrest Smyth
Guest

Great article Dr Fung. Of course salt is not the only thing that nutrition science has got wrong over the past 50 years! One thing I humbly question, though, is your assertion that there have been “dramatic improvements in health and lifespan” in the last 50 years. Lifespan perhaps (although the average lifespan of millennials may in fact be shorter than their parents and grandparents generations), but, as a consequence of a nutrient-deficient diet high in refined sugar, highly processed carbohydrates, natural fats being replaced by vegetable oils high in Omega 6, and chemical food additives, we now suffer from… Read more »

Carol
Guest
Carol

At our local toddlers play group I was talking to the mother of a three year old boy who had very high blood pressure since the birth and was told by her GP to cut out salt completely from her diet. Needless to say her BP never came down and she was being sent to various consultants who had no answer. I asked for her to just try, just for one week, putting salt back into her diet. A week later she came into the playgroup and just gave me the biggest hug – she blood pressure was normal and… Read more »

Gage Hastings
Guest
Gage Hastings

The zero sodium diet likely left her very deficient in magnesium as well. Very Low magnesium will definitely cause AF. Tell her to look up how to make magnesium water , also mention she might try magnesium oil as a transdermal method of increasing magnesium. A week at an ocean beach with a lot if time in the water will also raise magnesium levels as ocean water has a good deal of magnesium chloride in it.

Tom
Guest
Tom

Very interesting. But the article leaves people with high bloodpressure in the dark about what they should do about it. A friend of mine is very thin, sporty and only 50 years old. He eats very healthy, lots of vegs, fruit, nuts, etc. Hardly any sugar, processed carbs. Still he suffers from a high bloodpressure. His still relatively young parents both had strokes some years ago and of course he is very afraid to be next.
The GP tells him to either take medicin or reduce salt. He doesn’t want to take the medicine because of all the side effects.

Lucy
Guest
Lucy

maybe that bit of sugar is too much for him. Quit ALL sugar no exceptions and even limit fruit to berries and lower glycemic. Also check if he has sleep apnea.

Monica
Guest
Monica

Eating healthy often means low fat. High fat from butter, olive oil, fish, meat may actually be protective. Try it for a period and see what happens.

James
Guest
James

If I may quote Jesus Christ…. “Salt is good” 🙂

Jean Johnson
Guest
Jean Johnson

But salt that has lost its savor is good for nothing. Table salt has been processed of its minerals. Pink Himalayan and Celtic salt is whole salt and is good

Lucy
Guest
Lucy

I want to know if the low salt diet has caused this epidemic of dry eye diseases.

Gage Hastings
Guest
Gage Hastings

I was diagnosed with high blood pressure a few months ago. my BP was consistently around 160/ 90.I took a calcium channel blocker for a few weeks. No reduction in BP occurred over that time and I read about the negative side effects that can occur with prolonged use of such drugs. I decided not to worry about it for a couple months. Last week I tried a celery regimen that I discovered in the web. After just ONE week, my BP id down significantly , but only in the mornings. This morning my BP was 127/59. My evening BP… Read more »