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The War on Salt May Damage Our Health

Author: Jian Gao, PhD

Editor: Mr. Frederick Malphurs

April 7, 2024                                                                                                                                  

 

Restricting salt intake is the ‘law’ of the land – the academics, medical journals, government agencies, best-seller writers, and of course the pontificators have all jumped on the bandwagon, aiming at “an ideal limit of no more than 1,500 mg per day for most adults.”1 Even WHO (World Health Organization) has launched ‘WW III’ against salt: “Massive efforts needed to reduce salt intake and protect lives.”2

Disappointingly, the population-wide low-salt intake policy is ill-conceived based on erroneous data analyses and illogical reasoning, which is doing more harm than good.

We Owe Our Lives and Civilization to Salt

Salt, more exactly, sodium, is an essential mineral – we humans cannot survive without it – thanks to sodium, our heart keeps beating, our nerves can send signals to each other, our muscles can move, and our cells can feed themselves. Furthermore, the latest research suggests life on earth started from salt.3

Salt, the only rock we eat, has also fueled civilization from the very beginning. In fact, maps show early roads and “towns were placed and interconnected haphazardly without any scheme or design. That is because the roads were simply widened footpaths and trails, and these trails were originally cut by animals looking for salt,” wrote Mark Kurlansky in his NYT bestseller Salt: A World History.

“A substance so valuable it served as currency, salt has influenced the establishment of trade routes and cities, provoked and financed wars, secured empires, and inspired revolutions.”4 In fact, “The history of the Americas is one of constant warfare over salt. Whoever controlled salt was in power. This was true before Europeans arrived, and it continued to be the reality until after the American Civil War.”

“Until about 100 years ago, when modern geology revealed its prevalence, salt was one of the world’s most sought-after commodities.”5

Salt Is Not the Root Cause of the Worldwide Hypertension Epidemic

Salt intake was very high before the 1900s in Europe and the US because salt was used to preserve food. For instance, based on detailed records kept for revenue because of heavy taxation, the French consumed 13-15 grams each day.6 Salt intake was much higher in the Scandinavian countries, over 50 grams per day.  In the 16th century in Sweden, it is calculated the daily salt intake was about 100 grams per day when there was a high consumption of salted fish.6

Despite very high salt consumption, before the 1900s, hypertension prevalence was low – between 5 and 10% in western Europe and the US, and even lower in other regions (less than 5%).7

Since the introduction of refrigerators for home use in the 1930s, salt consumption has drastically reduced. Now the average salt consumption worldwide is about 9.8 g (3.95 g sodium) on average.8 In the US, the average daily salt intake is about 8.5 g (3.4 g sodium according to the FDA),9 and it is 7.1 grams in UK.10  

Strikingly, while the salt consumption has gone down, the hypertension incidence has skyrocketed in the last century – now it is between 30 and 40% across developed countries, and it is even higher in the US (48%) according to a CDC report.11

The opposite trends are evident too in fast-developing countries. For instance, in China, the hypertension prevalence was 11.3% in 1991. By 2015, it jumped to 37.2%.12 During the same period, cooking salt intake dropped by almost half from 12 to 6.3 grams per day.13

Clearly, the hypertension crisis was not created by salt consumption. And the argument that millions of years ago humans did not eat much salt so we should not is preposterous. It is true our early ancestors did not have table salt to add or processed food to eat, but those who lived close to oceans ate a lot of salt from seafood. Even for those who lived inland, many animals and insects they ate contained substantial salt (e.g., there are 0.453 g sodium per 100 g in some eatable crickets),14 and even some fruits are high in salt (e.g., there is up to 3.4 g sodium per 100 g in tiger nuts, a type of root vegetable).15 And bear in mind early humans and animals alike were constantly moving in search of salt sources such as salt lakes and salt licks.5

In essence, how much salt our early ancestors ate is anybody’s guess. And it is irrelevant anyway – one can readily argue our early ancestors died young because they did not have enough salt to eat – the life expectancy of our early ancestors (2.31 to 1.65 million years ago) was only about 12.8 years;16 and even just thousands of years ago, the average life span in ancient Greek and Roman times were in the range of 20 to 35 years17 

Taken together, it cannot be any clearer salt was not the culprit behind the worldwide hypertension epidemic. Correlation cannot prove causation, but it can disprove causation – we cannot blame frostbite for sunburn.

Salt is further exonerated by large cohort studies. The first large scale international study named INTERSALT study funded by multiple governments and other organizations around the world in the 1980s did not find any meaningful association between salt intake and blood pressure.18 In fact, after removing the four outliers (four primitive societies), among the 48 industrialized societies there appeared to be a negative trend – higher salt intake was associated with lower median blood pressure. Even one of the INTERSALT researcher members, Lennart Hansson, accepted “It did not show blood pressure increases if you eat a lot of salt.”19 

The null finding from INTERSALT was further confirmed by two other large studies (one was in Scotland and the other was international) – after adjusting for confounders such as age and education, these studies showed no correlation between salt intake and blood pressure.20-21   

Ironically, INTERSALT, which found no meaningful association between salt intake and blood pressure, has become one of the cornerstones for the low salt intake policy after some data dredging.19

Paradoxically, the largest salt-health study named PURE (Prospective Urban Rural Epidemiology; 102,216 participants from 18 countries) opposing the low salt intake policy showed a linear relationship between salt intake and blood pressure, albeit relatively weak.22 Along the observed linear relationship between salt intake and blood pressure, strikingly, the study, published in the New England Journal of Medicine in 2014, found low salt intake was associated with high risk of cardiovascular disease and total mortality.

But why did the PURE study observe a linear relationship between salt intake and blood pressure? In all probability, confounding was the culprit – the participants in the PURE study for sure consumed more processed food than those in the INTERSALT study conducted 30 years earlier. Nowadays processed food accounts for about 80% of daily salt intake.6 In addition to salt, processed food is also laden with other food additives and toxic chemicals that have been shown to induce hypertension.23-26 In essence, salt became the scapegoat for the toxic chemicals in the food.

In any event, salt intake cannot be the root cause of the worldwide hypertension epidemic – the opposing temporal trends of salt intake and hypertension prevalence has put that question to rest.

Salt Intake Restriction Acting Like a Diuretic Palliates the Symptom

Yet, the greatest smokescreen for the salt-hypertension theory and thus the low salt intake policy is the finding from randomized controlled trials (RCTs) showing restricting salt intake lowers blood pressure. Given that RCTs, the gold standard in gauging causal relationships, have demonstrated salt intake reduction can lower blood pressure, high salt intake must be the culprit behind the hypertension epidemic, and therefore, everybody on the planet needs to reduce salt intake.  

Unfortunately, this dogma cannot be more mistaken. Many things (e.g., water pills, dehydration, starvation, Atkins diet) can also lower blood pressure but they are not the root causes of the hypertension epidemic. It is true salt restriction can meaningfully lower blood pressure for about half of those who are hypertensive,27 but it does so by acting like diuretics (water pills) reducing water in blood vessels rather than addressing the root causes.

Counterproductively, the low salt intake policy has distracted the public from identifying and managing the root causes – research has clearly shown environmental chemicals induce hypertension,28-37 and other factors such as chronic psychological stress and micronutrient deficiency (e.g., vitamin D and potassium) play a role too.38-47

Low Salt Intake Can Damage Your Health

The low-salt-intake (LSI) advocates have been promulgating the extrapolation that millions of lives can be saved worldwide by just lowering blood pressure by 2 mm Hg. That could be true if blood pressure were lowered by addressing the root causes rather than reducing salt intake which works like a diuretic.

The linear relationship between salt intake and total mortality that the LSI advocates have claimed cannot be true – sodium in salt is an essential mineral, meaning humans cannot survive without it and there must be an optimal range – the notion that “less is better” makes no sense.

Bear in mind, to gauge the effect of a treatment or diet, the most important measure is total mortality, not a specific disease. Dying of other diseases while reducing blood pressure is not exactly the right thing to do. And let’s not forget restricting salt intake only meaningfully lowers blood pressure for about half of the hypertensives,27 does almost nothing to lower blood pressure for the normatives,48 and even raises blood pressure for some (about 15% of the normatives).49

Numerous studies have demonstrated a U-shaped relationship between salt intake and total mortality – both low and high salt intake kill people.7,50 However, the U-shaped relationship and the study authors have been ferociously attacked by the LSI proponents.51

The LSI proponents have claimed the linear relationship is correct because the estimate of salt intake is based on 24-hour urinary sodium collection, and the U-shaped relationship is wrong because the estimate of salt intake is based on spot urinary sodium collection.

Unfortunately, the LSI experts are mistaken. My recent study published in Research Methods in Medicine and Health Sciences has clearly demonstrated:

  • The U-shaped relationship is correct (it is not caused by the spot urinary sodium collection method) – low salt intake is associated with high mortality.
  • The linear relationship is erroneous (the finding is a result of random chance due to small sample sizes (the studies are too small) – the low salt intake policy is doing more harm than good.
  • Both the 24-hour and spot collection methods, in fact, underestimate the harmful effects of low salt intake and overestimate the adverse effects of high salt intake.
  • Mostly likely, the high mortality of those with high salt intake is due to the chemicals in the processed food rather than salt itself because a normal kidney can readily excrete 10 times the salt a person normally consumes each day.52,53

Incredibly, the LSI proponents did find the U-shaped relationship between salt intake and total mortality when combining small studies using 24-hour collection methods (the gold standard). Yet, they try to conceal the finding by hiding the U-shaped graph in the Supplementary Appendix (page 15; Figure S4) without mentioning it at all in the abstract or main text published in the 2022 January issue of the New England Journal of Medicine (NEJM).54 Knowing few readers would go beyond abstracts let alone appendixes, how could the NEJM editors let this happen?

How Much and What Salt to Eat?

Based on existing evidence in totality, the optimal sodium intake range for overall health is between 3 and 5 g per day (7.5 – 12.5 g salt).7 In fact, this range is supported by the result found and hidden by the LSI proponents analyzing the six studies using the gold standard method (24-hour urinary sodium collection), which shows the all-cause mortality rate was at its lowest level when daily sodium intake was about 3.5 g (8.75 g salt per day).52

As with any other treatments or diets, no one size can fit all. If you are hypertensive and reducing salt intake can meaningfully lower your blood pressure, salt restriction is indeed an option. But keep in mind that sodium is an essential mineral – there is likely a price to pay if salt intake is too low, which is reflected by the high total mortality rate. The best way to lower blood pressure is to address the root causes – stress, toxic chemicals (in food, water, air, and consumer products), gut dysbiosis, and micronutrient deficiency (especially vitamin D and potassium).  

Given the optimal range, is one type of salt better than another? Not so much for blood pressure itself but maybe for overall health. By and large, sea salt from oceans nowadays is heavily polluted with heavy metals and other toxic chemicals from the rapid industrialization around the world in the last 40 years. On the other hand, table salt is pure (only contains sodium bound with chloride) but does not contain other minerals our body needs.

Two better alternatives are Redmond Real Salt (minded from an ancient seabed in Redmond Utah) and Himalayan Salt (mined from the Punjab region of Pakistan) – both containing more minerals that our body needs without modern pollutants. For more information about salt and health, The Salt Fix by Dr. James DiNicolantonio, a cardiovascular research scientist, is a great book to read.

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About the Author and Editor: Jian Gao, PhD, is a healthcare analyst/researcher for the last 25 years who devoted his analytical knowledge and skills to understanding health sciences and clinical evidence. Mr. Frederick Malphurs is a retired senior healthcare executive in charge of multiple hospitals for decades who dedicated his entire 37 years’ career to improving patient care. Neither of us takes pleasure in criticizing any individuals, groups, or organizations for the failed state of healthcare, but we share a common passion – to reduce unnecessary sufferings inflicted by the so-called chronic or incurable diseases on patients and their loved ones by analyzing and sharing information on root causes, effective treatments, and prevention.

Disclaimer: This article and any contents on this website are informational or educational only and should by no means be considered as a substitute for the advice of a qualified medical professional. It is the patients and caregivers’ solemn responsibility to work with qualified professionals to develop the best treatment plan. The author and editor assume no liability of any outcomes from any treatments or interventions.

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