As part of a so-called healthy lifestyle, guidelines from health professionals and the Government tell us to restrict salt to less than a teaspoon of day, equivalent to 2300 milligrams of sodium, which constitutes half the make-up of salt.
But has anyone ever questioned the rationale behind this and published the results? Dr James Dinicolantonio, a cardiovascular research scientist, has, and his results might astound you. He explains how we have been demonising the wrong white crystal all along, and goes as far as to say that implementing the outcome of his findings might even save your life. Far-fetched? Read on...
How did the current guidelines to restrict salt come about?
The knee-jerk reaction by just about everyone, ourselves included, is to initially think that the guidelines can’t be wrong. After all, if they are endorsed by the government and health professionals alike, and have been in place for quite a while, and maybe even your GP has told you to cut down on salt if your blood pressure has been creeping up, how can it be wrong?
Well, the first thing to understand is that the guidelines are based partly on a gross oversimplification of the salt intake of our ancestors, which was actually much higher than originally believed, and also on a hypothesis, which has never been substantiated by any evidence. In fact, there is now considerable evidence against the hypothesis, but by the time this was coming to light, the government and health bodies that had put their heart and soul into the low salt message were too far down the line to want to lose face with an about-turn! (The situation is the same with saturated fat, by the way, but that’s another story. Or blog).
In fairness, as far as theories go, it is actually quite a plausible one in its simplified form. It was postulated some time ago that consuming a lot of salt would cause the body to retain water to maintain the correct concentration of sodium in the blood. Maintaining this concentration is pretty important, by the way, as we’ll see in a moment. So, this means that there is extra water in your blood, and to pump this increased volume of blood around requires extra force, hence the increase in blood pressure, which is essentially a reflection of the effort being made by the heart. Sounds about right so far, doesn’t it?
So what’s wrong with the current guidelines?
Salt is such an important part of our diet, and an important part of us, even, (we did, after all, evolve from the sea) that the body is adept at regulating the concentration itself, because it is essential to life; in other words, our salt “thermostat” is a survival mechanism. Unless you are one of a few salt-sensitive individuals, you have to eat a colossal amount of salt to see even a slight elevation in blood pressure. Put simply, if you eat more salt than the body needs, then sodium is filtered then dumped via the kidneys, and if you don’t eat enough, then the body retains it by reabsorbing it after filtering at the kidneys. And it would seem that trying to override this innate ability to control sodium by changing your diet is pretty much impossible.
Incidentally the kidneys deal with the amount of recommended daily sodium intake (either filtering it and dumping it, or filtering it and reabsorbing it) every five minutes, which gives you some idea of just how capable the body is when it comes to dealing with fluctuations in salt intake.
Is there any downside to a salt-restricted diet?
Now, if that was the end of the story, it would all be fine. The worst case scenario to unnecessarily restricting salt would simply be that your food tastes more bland than it needs to whilst the kidneys reabsorb back every morsel of sodium that it filters. However, the picture of salt restriction is a little more sinister than that. Let’s have a look in a bit more detail at what happens when you restrict salt.
First, we need to understand how important it is to maintain the correct concentration of sodium in the blood. If the blood has too little salt in it, then water from the blood moves into tissues so that blood concentration increases, swelling tissue cells in the process. The converse also happens. If the blood has too much salt in it, then water moves from the tissue cells into the blood to dilute it, causing cell shrinkage. Both swelling and shrinkage of cells can cause an enormous amount of damage or even death (for example, in the case of brain cells swelling), which is why the kidneys go to great lengths to maintain the blood sodium concentration.
It starts with dizziness and fatigue...
So, in the case of a low salt diet, once the kidneys are at full whack in terms of reabsorbing back every drop of sodium, but the blood concentration is still too low, then it’s time to dump water from the blood. In comes dizziness and fatigue from low blood volume.
Apart from the dizziness and fatigue, you could be forgiven for thinking, “But at least my blood pressure is low!” However, if we keep going with the salt thermostat story, you’ll see that you don’t even get that from it....
Your body thinks you are severely dehydrated...
Once the volume of blood drops below a certain level, sensors in two of the main arteries (aorta and carotid, if you’re interested) detect this and tells the brain that the body is at a point of life-threatening dehydration. This is one of those situations where the brain yanks the body’s emergency cord. In other words, this is a life-or-death crisis which need to be fixed NOW, meaning that not a lot of thought is given to the health implications of its emergency contingency plan further down the line. (And why would it? There’s no point factoring in long-term health consequences if you’re going to be dead).
The risk of cardiovascular disease increases....
So the first thing that happens is that the smaller arteries constrict themselves by becoming more rigid, which raises blood pressure back up (kind of defeating the whole object of a low salt diet!), so that the heart can continue to pump the lower volume of blood around. In moments of temporary but acute dehydration, this is no bad thing, as it ensures a continuous blood flow to your brain and other vital organs. Do it day after day for a number of years, though, and permanently hardened, rigid arteries will be having an impact on your cardiovascular health. Your blood pressure certainly won’t be reduced long-term; more likely, chronically elevated.
Part and parcel of this emergency situation is that the heart rate increases. An elevated heart rate (which will be at least an extra four beats per minute) has a rather alarming association with cardiovascular disease because the heart can only receive an oxygen supply when it is in the relaxed state and not contracting. A faster heart rate means that it is contracting more often, so there is less relaxation time, resulting in an overall inadequate supply of oxygen to the heart, making a heart attack more likely.
This is why, if you are on a salt-restricted diet to reduce blood pressure, you are unlikely to see a drop of anything more than about 2%, which is nothing, certainly not what your doctor was hoping for. You will, however, see an increase in heart rate of about 10%. Ask your doctor which of those two changes has the most impact on likelihood of cardiovascular death....
You become predisposed to metabolic syndrome, obesity and diabetes...
As we’ve said, when you restrict salt to the point that your blood volume is low, your body will do anything to hold on to it. Unfortunately, one of the mechanisms employed to achieve this is to increase insulin output, and it does this by creating a state of insulin resistance. This means that the body is less able to shuttle glucose into cells to be used for energy, making it produce more insulin to try to compensate (and hanging on to sodium, and therefore blood volume in the process). Inevitably, a state of insulin resistance ends up with you converting most of your food to fat for storage instead. This has been explained in a previous blog, but essentially a cascade of hormone reactions effectively start to derail your metabolism: you can’t convert food to energy so not only do you lack energy, but you store the glucose as fat instead, so now you’re getting fatter, and your hunger goes into overdrive because your body thinks you are starving, so you eat even more whilst becoming all the time more tired, sick, fat and lethargic. Insulin resistance is the precursor to diabetes and dementia (sometimes dubbed diabetes type 3). Obesity itself predisposes to chronic inflammation as visceral fat releases inflammatory hormones, now known to be associated with most of our western diseases: cardiovascular disease, many types of cancer, diabetes, Alzheimers. Essentially, the body is now sick and primed for disease.
Kidney function declines, existing kidney problems deteriorate...
Salt-restricted diets have been touted as a way to prolong optimum kidney function for longer (kidney function naturally declines with age), a sort-of “spare the kidneys for as long as possible” idea. However, it’s now known to be nonsense: a low salt diet causes the kidneys to have to reabsorb most of the sodium that goes through its filter system, which requires an enormous amount of energy, effectively depleting them over time, and wearing them out more quickly. Kidney function actually improves when salt isn’t restricted.
Trying for a baby? Even fertility declines....
Here’s a couple of other things that happen down the line: fertility is reduced, birth weight is reduced, and weaning time is increased. These are things that any farmer knows, hence the importance of salt licks for reproducing livestock.
When you consider that sodium is essential for optimal heart contraction, digestion, cell-to-cell communication, bone formation, optimal functioning of cells and muscles, and nerve impulse transmission between organs, you can understand how many other conditions arise from long-term salt restriction. This is the rationale behind Dr Dinicolantonio’s claim that eating salt “might save your life”. Maybe not so far-fetched after all...
If you’re left wondering what does cause high blood pressure, as you probably guessed, the comment about demonising the wrong white crystal in the introduction was a reference to refined sugar. Sugar raises insulin, and constantly elevated insulin levels will raise blood pressure. It’s not the only cause, of course. Stress is heavily implicated, too, both causing a state of chronic inflammation and disease. If you’re sceptical, try this for just one week. Cut out all refined sugar and as much refined carbohydrate as you can (since it quickly converts to glucose during digestion), whilst eating as much salt as is required for food to taste “right”, and do this for a week. Take your blood pressure before you start and at the end. If you’re on antihypertensive medication, take your blood pressure daily, in case you need to reduce the dose.
So now you’re probably thinking, well how much salt should I eat? We’ve already mentioned adding enough salt to make food taste “right”, and it really is that simple. Bear in mind that, unless you are one of a few salt-sensitive individuals, you would have to eat a colossal amount of salt to see an elevation in blood pressure, way more than you would want to eat, and way more than the amount that makes your food palatable. Salt isn’t addictive. In direct contrast to sugar, it doesn’t feed into the reward pathways of the brain, making you crave more and more. Also in contrast to sugar, it’s essential to life, and so we naturally eat more when we need it, and less when we don’t. All animals and all human populations, regardless of location and culture, have been shown to have a natural set point of salt intake when it’s unrestricted. For us humans, it’s between about one and a half and just under three teaspoons. Bear in mind, though, that our bodies can sometimes need more than this because of modern health and lifestyle habits, such as medications, including antidepressants and diuretics, caffeinated drinks, and low carb and intermittent fasting diets (which cause a significant drop in insulin).
You will, quite simply, naturally eat what you need, once you let your body tell you what that is, rather than the other way round. Just one recommendation: eat real, unadulterated rock salt or sea salt. Not that bleached stuff with artificial anti-caking agent and god knows what else, usually sold as “table salt”. You will then benefit from a nice blast of other essential minerals, such as potassium, iodine and magnesium whilst avoiding the nasties.
In summary, there is no doubt that it is time to recognise that science has moved on, and in fact, did so some time ago. Dietary guidelines now need to move on, too.
Reference and Recommended Reading: The Salt Fix by Dr James Dinicolantonio
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