Salt: Friend or Foe?

the-salt-fixThe health effects of salt consumption is one of the most contentious topics in nutrition at the moment. Whereas some nutritionists and other health professionals argue that salt is our friend, others make the case that we would be wise to limit our intake of this white substance. Personally, I fall into the latter category.

Among all of the books, presentations, and articles that have contributed to fueling the salt debate, the recently published book entitled The Salt Fix is high on the list of those that have poured the most gasoline on the fire. In today’s article, I thought I’d share some quick thoughts on that book.

Should we abandon the idea that salt is bad for us?

I don’t have a habit of criticizing books that I don’t like here on the site. The reason I’m making an exception for The Salt Fix is that this book expresses an idea that in my opinion is very destructive, namely the idea that it’s not only unproblematic to take in a lot of salt, but that a lot of people would actually benefit from consuming more salt, as opposed to less. If this book had largely gone unnoticed by the public, I wouldn’t have been particularly concerned about its destructive nature. Unfortunately though, it not only hasn’t gone unnoticed, but some people seem to be embracing it and the message it brings out to the world. I think this is worrying, seeing as my impression is that the book is not based on good science and contains harmful nutritional advice.

To begin with, I want to point out that I have not read The Salt Fix. My thoughts in this article are based on what I’ve read about the book online, as well as statements I’ve seen the author make. I know that it’s obviously best to read a book before criticizing it, but I felt like it was okay to not do so in this situation, seeing as the book doesn’t hide what it is (I feel like I have a fairly good understanding of what it’s about) and I’m not planning to write a comprehensive critique of the book. Rather, I just wanted to share some quick thoughts on the foundational premise of the book and the message it brings out to the public. I don’t want to read The Salt Fix and don’t plan to read it, seeing as I don’t want to waste my time by reading a book that is based on a premise that is not grounded in good science. If you feel I’m misinterpreting the author’s intentions or underestimate the quality of the book, then don’t hesitate to let me know in the comment section below this post.

The Salt Fix is based on a fallacious premise

Upon seeing and reading the description of The Salt Fix, the first thought that came into my head is that the book is based on an idea that isn’t evolutionarily grounded. In order to illustrate this, I’ll share my thoughts on two statements that describe the opinions of the author and the contents of the book. The first one is a statement that the author made about our salt requirements in an interview at BeWell.com. Here’s what he had to say:

In fact, because our body drives us to consume around 8 to 10 grams of salt each day, if processed foods are lower in salt we will likely end up eating more of them to get the salt our body craves.

My comment: I have no idea what the author bases that statement on. It’s not science, that’s for sure. Such a statement would never make it through a high-quality peer-review process. Humans evolved eating a diet composed exclusively of real, whole foods. Our ancient ancestors obviously didn’t have access to table salt or highly processed, salty foods such as potato chips or crackers; hence, I don’t see how they would be able to take in as much as 8 to 10 grams of salt every day, which is a lot. It’s well-established that some of our primal forebears occupied land-water ecosystems and exploited aquatic resources (1); however, as a whole, the evidence clearly suggests that salt did not make up a large part of ancient human diets (2, 3, 4, 5, 6).

Here’s what a 2015 paper entitled Links between dietary salt intake, renal salt handling, blood pressure, and cardiovascular diseases had to say about this issue:

Observation and intervention studies in humans and animals support the view that the excess of salt in our diet is a major environmental factor participating in the development of hypertension and cardiovascular diseases. This finding is coherent with our knowledge on the environment in which the genetic makeup of terrestrial mammalian species has evolved for dozens of millions of years. The food consumed by terrestrial mammals, including primates, never contained a lot of salt. Indeed, except for rare cases, plants contain only traces of salt, and the consumption of very large amounts of fruits, roots, leaves, or seeds does not bring much salt in the organism. For omnivorous and carnivorous species, the occasional or regular absorption of meat increases salt intake, but in limited proportions because the eaten meat corresponds most often to the sodium-poor intracellular medium and not to the sodium-rich extracellular medium that is generally lost when the animal is killed or cooked. (2)

It’s only very recently that large quantities of NaCl, in the form of highly processed foods, sports drinks, and table salt, were infused into the human diet. Our nutritional requirements were determined in the past as a result of selective forces acting upon the human gene pool. It makes absolutely no sense that we should know require a lot more salt than we used to. Certain illnesses and behaviors can indeed alter one’s nutritional requirements; however, to suggest that the human body requires 8 to 10 grams of salt per day to function properly is in my opinion ludicrous.

The next statement I want to share my thoughts on is the following statement found in the description of the book on Amazon:

Too little salt in the diet can shift the body into semi-starvation mode and cause insulin resistance, and may even cause you to absorb twice as much fat for every gram you consume.

My comment: I don’t know whether it’s the author of the book or some other person who penned that sentence, but seeing as it appears in the main description of the book on Amazon, I see no reason to doubt that it reflects the ideas the author presents in the book. I very much question the validity of the statement and would argue that it’s very difficult to take in too little salt. Whole foods diets that contains no added salt are by default low in NaCl. Most contemporary hunter-gatherers, including those who live in a part of the world where our species is thought to have originated, take in very little salt, but are lean and have low blood pressure nonetheless.

Here’s what a 2013 review paper had to say about this matter:

Observations in contemporary no-salt societies confirm not only the relation between salt and hypertension but also provide evidence of successful adaptation to salt-free environment during the evolution of the human species. For example, the Australian aborigines, the African Bushmen, or the Amazonian Yanomami had no access to salt in their diet until recently. Their total salt intake was found no more than what they could obtain from natural sources—based on the typical hunter–gatherer diet, which is only around 0.25 g per day. Hypertension is simply non-existent in such societies. Yet, when such communities are urbanized and exposed to the salty modern diet, they do suffer from hypertension and its complications, in some cases at disproportionately higher rates than the rest of the population. (4)

Given that it’s only very recently that large quantities of salt were infused into the human diet, it’s not surprising that a large body of evidence indicates that it’s unhealthy to consume a lot of this mineral (2, 3, 4, 56, 7, 8).

The bottom line: As I see it, the idea that it’s unproblematic to take in a lot of salt is not based on good science and lacks evolutionary support. I would argue that most people would benefit from taking in less salt, not more!

Comments

  1. Hi Eirik. I think it could be argued that salt is both friend and foe. The human body needs some salt for good health but too much can definitely be problematic. I don’t think medical research has a good handle on what is an ideal amount. Likely it depends a lot on the individual and the ancestry of each of us.

    Just guessing here, but possibly those of us of European descent (for example) have evolved to require (or perhaps tolerate is a better word) slightly more salt than those of aborigine descent.simply because our early ancestors did have better access to it. I agree, however, that most of us do consume considerably more salt than our bodies actually need.

    I think most of us can handle salt quite well–up to a point. Obviously cultures that evolved on considerably less salt would tend to be salt-sensitive and react poorly when exposed to a saltier diet. It doesn’t necessarily follow, however, that we would all react poorly.

  2. I listened to his podcast a few weeks ago with Robb Wolf and thought it was interesting at least. I have not read the book but I thought he made some good points during the podcast.

    Regarding a higher salt intake for people or athletes who exercise a lot. You lose upwards of 800 mg of sodium per hour, whereas sports drinks typically only have 300-400 mg in them(not to mention the sugar). If you exercise more like a lot of people then you could lose 1200-1500 mg of salt.

    The current recommendation of doctors to take less than that a day means they are in the negative for fluid sodium. He said something in regards to chronic elevated aldosterone in this situation leading to problems.

    He seemed to think Cordain underestimated salt intakes of hunter-gatherers – stating that he purely used muscle meat and ignored the salt found in blood that would have been consumed.

    I thought it was interesting he said that while you may see a reduction in blood pressure with reduced salt you will get up to a 25% compensatory rise in heart rate for the body to maintain homeostasis.

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