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A surprising effect
We've been told our whole lives that salt raises your blood pressure and if you want to bring yours down, you have to cut the salt. But science is evolving fast on this and we now understand there's a lot more to the story because the recommendations worldwide are to stay under a specific amount of salt in the food. But does that apply equally to everyone? Does that apply to you?
To answer this question, scientists took 213 people and they put them on two different diets, high salt and low salt. So, what's high salt and what's low salt? Just to give you an idea, the recommendations worldwide are to try to stay under two grams of sodium daily. So, WHO and European organizations, that's the cut off. In the US, it's a little different. Sometimes under 2.3. Some recommend the ideal range is under 1.5, but that's the general ballpark.
Now, that's 2 grams of sodium. Table salt, the regular salt we use at the table, roughly half of that is sodium. So, 2 g of sodium would be about 5 g give or take of salt, which is about a level teaspoon. And that's total sodium daily, right? Including the sodium that's naturally present in foods and sodium added total over the course of the day, two grams. So it's pretty low. So that's just to give us some reference.
Now the investigators estimated the sodium intake of the participants before the trial on their usual diet and it came down to about 4.5 grams a day. So about twice those recommendations, the cap given by the WHO and other organizations. And then on the two diets of the trial, the low sodium diet, they ended up eating about 1.3 grams of sodium a day. The investigators actually wanted to shoot for 0.5 grams daily, but they couldn't get the participants to cut back so much. So they ended up eating about 1.3. And on the high salt diet, it was about 5 grams a day of sodium. So big difference between the diets, about a three-fold difference, give or take. And interestingly, these two levels of intake from the trial, they do cross the guidelines. So one is lower and one is a lot higher. So there should be a really good test of the value of this cutoff used in the guidelines.
So this is the average of all the participants. This is what they reported. They start out at baseline on their regular diet and then they go on to the study diets, high salt and low salt, for about a week, and then measure the blood pressure before and after. And what they report is that the blood pressure was higher on average on the high salt diet, about an 8 point difference, 8 millimeters of mercury, which is in the range of some common blood pressure lowering medications. So it's a substantial difference. This is for systolic blood pressure, the top value on your reading.
Then they switched everybody to the other diet. This is called a crossover trial. Everybody goes on both diets. So the people who were on the high salt diet go on low salt and vice versa. The difference was a little smaller but overall the same general direction of effect. The folks on high salt had higher blood pressure.
Startling Implications
Now, this is where it gets interesting because this is the average of everyone. Now, let's look at the results individually, per person. Each of these bars is one person, one individual participant. And these are the results comparing low salt to high salt, basically the effect of increasing salt in the diet by about three-fold, which is what they did in the study. So, you see that some people saw a massive increase in their blood pressure, close to 50 points, which is gigantic. The vast majority were much lower than that: some around 20 points, many around 10 points.
But look at this other side over here. There were a significant chunk of people whose blood pressure came down on high salt. Some, the most extreme, saw a decrease of 30 to 40 points. Massive. The majority again are around 10 points or so, a little five to 10 points.
Now this study had some limitations, but this is not an isolated finding. Numerous studies have now done this, broken down the results per participant, and this is a pretty consistent finding. We see a huge spread. Some people go up, some people go down, and some people don't see much of a difference. The exact number of people that have this paradoxical response, where their blood pressure actually improves on high salt, varies. One analysis estimates that it's about 15% of the population. So this has been seen and reported so many times it even has a name. It's called inverse salt sensitivity. If your blood pressure goes up significantly on high salt, that's called salt sensitivity. If you don't see much of a change, that's called salt insensitivity. And if it comes down, it's called inverse salt sensitivity.
Next, we're going to talk about some powerful ways to lower blood pressure that are neglected and not talked about much, both for these folks, particularly interesting for people with inverse salt sensitivity, but also ones that work in general. But first I want to point out a caveat. This result, this heterogeneity, and some people having this paradoxical response, in all rigor, this could just be variability. If you run the trial, there's going to be a spread of results, and if you test the same people again, those people are now going to go up, so they're not legitimately inverse salt sensitive. The real way to nail this is to run the trial twice. Basically, you want to test the exact same people twice on the same exact diets and check that the response is the same. Both times, when you raise the salt, their blood pressure drops. As far as I know, this has not been done specifically for this population of inverse salt sensitivity, so it hasn't been formally proven. I think it's very likely that this is real, not just because we see it over and over, but because some studies have even identified genetic differences between these folks and those who have a more typical response where blood pressure goes up with salt. So I think it's probably real, but for rigor, we should state that.
And if this is a real phenomenon, think about the implications, because the guidelines and recommendations are the same for everyone, but they could have a monumentally different impact on different people. It's true that most people in that experiment saw their blood pressure go up when they upped the salt. So the average aligns with the guidelines and recommendations, and it's true that a lot of people in our society, a lot of Westerners and a lot of non-Westerners as well, consume too much sodium and would be better off consuming less. That's all true, and in fact that's my case. When I reduce sodium, my blood pressure comes down 10 points or more. But according to that experiment, it's also true that for a chunk of people that doesn't apply, and that's potentially millions of people. Now, of course, guidelines for millions of people have to give some general direction that has to be aligned with the average, so that's understandable. But at an individual level, do you care what the average of the population is? Not at all. You care what happens to you. So measuring your own blood pressure, which is quick, painless and non-invasive, and playing with the factors in your food and watching what happens over time, is going to be much more informative for you and your health than going by these cut offs that are the average for everyone.
Now, how does this work? Why do some people seem to have this paradoxical response? The exact details are being worked out, but one proposed mechanism is that when most people cut salt, there's a specific pathway called the renin-angiotensin pathway that signals to your kidney to hold on to more sodium, to reabsorb it, to pull it from the urine, and basically for your body to conserve more sodium. Your body is sensing that there's less sodium coming in through the diet, so it's compensating by holding on to more of it. It's an evolutionary mechanism. In most people this compensation is incomplete, especially over the long run, and so blood pressure ends up going down if you cut salt. But the proposed idea here is that in some individuals their compensatory mechanism is so effective that they overshoot. Their body now conserves so much sodium when they cut salt that their blood pressure actually goes up.
Now the million-dollar question is: if you have inverse salt sensitivity, should you just load up on salt in the diet? There's very little research on these folks to understand the long-term consequences of each choice. It's probably true that these people don't need to be as strict as everybody else. But one thing to bear in mind is that there are other consequences and other conditions linked to excessive salt intake beyond high blood pressure and cardiovascular disease. For example, the risk of stomach cancer goes up as well.
Neglected triggers for blood pressure
Let's talk about some key natural mechanisms to lower blood pressure that are usually not talked about much, because sodium and salt are the main things we hear about. Let's go over the five main ones quickly. These work in general for most people, but they're especially interesting for people with inverse salt sensitivity.
One key nutrient when it comes to blood pressure regulation is magnesium. Magnesium supports nitric oxide production in your endothelium, the lining inside the arteries. That helps you relax your blood vessels, and blood pressure comes down. Magnesium is present in a lot of healthy foods, but it's very often under-consumed in our society. The most concentrated food in magnesium is actually pumpkin seeds. Hemp seeds and cacao powder are two other really concentrated sources. Chia seeds and black beans are other good sources of magnesium as well.
The next powerful trigger for regulating blood pressure is potassium. Potassium has a fascinating mechanism: it signals your kidney to excrete more sodium, to get rid of it. This works in general for most people, and it has been shown in randomized trials that increasing potassium in your diet helps lower blood pressure. But this could be particularly interesting for people with inverse salt sensitivity, because remember, the problem there may be that they hold on to too much sodium. So if potassium counters that, it could be a great strategy that hasn't been shown scientifically. Again, unfortunately, we have very little research on inverse salt sensitivity people, but this is something I would 100% test if I were in those shoes. The most concentrated sources of potassium, which a lot of people don't know, are green vegetables. Beet greens or Swiss chard, beans and fruit are good sources as well. It's funny that if you ask people what has potassium, everybody says banana. A medium banana has about 400 milligrams of potassium, but the same weight of cooked beet greens has about 900.
Next trigger. One common question that comes up a lot when we talk about blood pressure is insulin. A lot of people ask, is insulin a trigger? Is it a cause of hypertension? We know that when we lose weight, our insulin levels consistently drop, especially fasting insulin. So it could be that insulin is one of the mechanisms, one of the reasons weight loss is so powerful at bringing down blood pressure, because insulin can also signal to the kidney to hold on to more sodium. Just like we saw with potassium, weight loss works in general. It has been shown in randomized trials to be very powerful, but it could be particularly interesting and particularly effective for people with inverse salt sensitivity.
The last two triggers, quickly. One is reducing alcohol intake. Randomized trials have shown a drop of about five millimeters of mercury in systolic blood pressure when alcohol intake is reduced. However, this is seen in people who regularly consume substantial amounts, more than two drinks a day, which is pretty substantial. If your intake of alcohol is more modest, you might not see as big a drop. Finally, improving sleep quality and reducing stress levels also seem to help reduce blood pressure. There's some promising data there, and we covered all the tips and tricks to naturally improve your sleep in a previous video. So check that out, and I'll see you in there.