In 1942, a 33-year-old woman walked into a hospital with a blood pressure so high, it was destroying her eyes. Her kidneys were failing. At the time, there were no effective treatments. So in a last-ditch effort, her doctor — a German refugee named Walter Kempner — put her on a radical experiment: nothing but rice, fruit, and juice. Almost zero salt. He told her to come back in two weeks [1].
But Kempner had a thick German accent. She misunderstood — and came back in two months [1].
When she returned, instead of being dead or malnourished, her blood pressure had dropped from 190/120 to 124/84. Her eye damage had resolved. Her previously swollen heart had shrunk [1]. By accident, Kempner had stumbled onto something extraordinary.
That was over 80 years ago. Yet we're still arguing about salt. And depending on which side you believe, you're either slowly destroying your heart — or you're following advice that could actually make things worse.
There are viral videos telling you that you don't need to cut down on your intake. While at the same time, the American Heart Association says we should ideally stay below 1,500 mg of sodium a day to improve blood pressure and heart health [2].
Thankfully, a brand new study just dropped — a massive digest of all the research to date — that finally clarifies what the evidence actually says.
Table of Contents
- The Scientific Consensus on Salt
- Dahl and the Genetic Factor
- The Contrarian View
- What the New Study Found
- Practical Takeaways
- References
The Scientific Consensus on Salt
Kempner's accidental discovery was followed by decades of research. And the consensus that formed was clear and nearly unanimous. The American Heart Association isn't an outlier.
Quick note: sodium and salt aren't the same — salt is about 40% sodium, which is why the WHO's 2,000 mg sodium limit means about a teaspoon of salt [3].
A landmark study in 1988 — INTERSALT — tracked sodium in the urine of 10,000 adults across dozens of countries and found a clear association: more sodium, higher blood pressure [4].
Then a randomized controlled trial — the DASH-Sodium trial — went further. It tested three sodium intake levels across two different diets, and in both, reducing sodium led to significant drops in blood pressure — especially for those who started with the highest levels. The combined effects of the low sodium DASH diet versus the high sodium control diet on systolic blood pressure were -5.3, -7.5, -9.7, and -20.8 mmHg across baseline blood pressure strata [5].
And when researchers followed a group that had participated in a sodium reduction trial for 24 years, those with an intake under 2,300 mg had a 25% lower risk of death than those getting between 3,600 and 4,800 mg [6].
Lower salt, lower blood pressure, longer life. Case closed — or so it seemed.
Dahl and the Genetic Factor
But even in the early days, there were hints that the story wasn't so simple.
In the early 1960s, a physician named Lewis Dahl at Brookhaven National Laboratory started feeding rats high-salt diets. Some rats got hypertension. Others were completely fine. So he selectively bred them. Within just three generations, he had two distinct lines: salt-sensitive rats that died of hypertension on a high-salt diet, and salt-resistant rats that were totally immune to it [7].
It was the first clear proof that salt sensitivity has a genetic component — and that not everyone responds to salt the same way. Remember that. It becomes important later.
Dahl spent the next 15 years proving salt's dangers — he even fed commercial baby food to his salt-sensitive rats and watched them all develop hypertension, which triggered a US Senate investigation into sodium in infant food. In 1975, he won the Ciba Award — the highest prize in hypertension research [7].
The Contrarian View
But then a widely-discussed study raised a serious objection to the consensus.
In 2014, cardiologist Salim Yusuf and epidemiologist Andrew Mente at McMaster University published a study that would ignite a scientific war. Their team analyzed urine samples from over 100,000 people across 17 countries, looking for indicators of sodium and potassium levels. Over a follow-up period of almost 4 years, they checked to see how heart attacks, strokes, and deaths related to these levels [8].
Partly, what they found matched the established picture. When sodium intake was high, there was an increased risk of death, heart attacks, and strokes [8].
But they found something else that was surprising. Low sodium intake was also associated with elevated risks of heart attack and stroke. As compared with the reference range, an estimated sodium excretion below 3,000 mg per day was also associated with an increased risk of death and cardiovascular events [8].
In other words, the data revealed a J-shaped curve. It wasn't a case of "the less sodium, the better." Instead, there was an optimal range that the research placed between 3,000 and 6,000 mg a day [8].
As Mente put it in an interview: "Sodium is an essential nutrient. It's not tobacco. Without sodium, you die. The optimal level of tobacco is zero, but with sodium, it's not zero" [9].
How Much Salt Should You Actually Be Eating?
Salt recommendations depend on your blood pressure, medications, and kidney function. Get personalized dietary guidance based on your health profile.
Try Health Roadmap — FreeThe response from the medical establishment was immediate — and personal.
Yusuf, the study's lead, later described it bluntly: "There has been a smear campaign by a group of people against anybody who questions salt. The moment you stand up and say, 'Well, it might not be as bad as we think,' you get attacked personally" [10].
Daniel Jones, speaking on behalf of the American Heart Association, fired back: "This is a flawed study, and no health policy should be based on this study" [11].
Critics of the prevailing view were quick to point out a glaring potential problem. Both the WHO's recommendation of staying under 2,000 mg/day and the American Heart Association's ideal target of 1,500 mg/day are significantly below this sweet spot of intake. The worry, according to Mente, is that if we try to lower our sodium intake this much, we might actually be doing harm and raising our risks — the opposite of what we're trying to accomplish.
So the critics conclude that maybe most of us shouldn't really be trying to lower our sodium intake, after all. Especially if our potassium intake is adequate. Because there was another important finding of this study and others as well. Higher potassium intake lowers our risks of heart attacks and strokes [8]. It does so by helping to lower blood pressure, especially when it's high [12].
And there are certain conditions where the people who have them need to try to increase sodium intake. One example is postural orthostatic tachycardia syndrome, or POTS. It's a condition where the body struggles to keep blood flowing to the brain when a person stands.
All of this has generated a lot of confusion that's made people unsure whether they should set the saltshaker down or pick it up.
What the New Study Found
So who's right — the guidelines that say cut sodium as low as possible, or the PURE researchers who say that could actually hurt you? A brand new study gives us the clearest answer yet.
The study isn't just another trial that gives us one more data point. And it isn't even a meta-analysis that pulls together the results from several trials. Instead, it's essentially a meta-analysis of meta-analyses of randomized controlled trials and observational studies. It's like a massive digest of all the research conducted to date on the topic of sodium intake and heart health [13].
The headline findings reinforce the consensus. Low sodium intake is associated with reduced risk of heart-related and all-cause mortality. It slashed the risk of death from strokes by 26%. High sodium intake raised stroke mortality by 40%. Each extra 1,000 mg/day of sodium raised heart disease and stroke risks by 4% and 6%, respectively [13].
So that settles it, right? Not so fast. What about Mente's J-curve — the finding that going too low also increases risk?
This is where it gets interesting. The umbrella review found no signal of elevated risk at low intakes. No J-curve [13].
But if low sodium is safe, why did the PURE study find the opposite? The PURE researchers had proposed a mechanism: when sodium drops very low, your body panics. It activates a backup system — hormones that squeeze your blood vessels tighter and force your kidneys to hold onto every last grain of sodium. Think of it like a thermostat that overreacts to a small temperature drop by cranking the heat to maximum.
This system — called the renin-angiotensin-aldosterone system — can contribute to heart disease when it's chronically overactive [13].
So is this backup system a real danger? The umbrella review checked. They found evidence of partial activation — but the response was mild. And with sustained lower intake, the body adapts. Evidence suggests that with prolonged sodium reduction exceeding one year, compensatory RAAS activation diminishes over time [13].
But the researchers found something that adds important nuance — and it brings us back to Lewis Dahl's rats from the 1960s.
The response to low salt intake was not uniform across populations. It significantly lowered blood pressure in the Western Pacific, Europe, and Southeast Asia — but not in the Americas [13].
Similarly, high salt intake wasn't significantly associated with heart disease deaths in U.S. populations, but was strongly linked in Japanese populations. This could reflect different dietary patterns. It may also be a function of differences in sensitivity to sodium [13].
So was Mente wrong? Not entirely. The umbrella review found no J-curve for mortality — but his observation about population differences turned out to be real. Dahl proved that salt sensitivity is genetically determined — some rats were profoundly affected, others barely at all. Sixty years later, the same pattern shows up across human populations. One size doesn't necessarily fit all. The critics of existing salt guidelines will likely feel vindicated by that part.
And it's also fair to admit: it is theoretically possible for our sodium intake to be too low. It's estimated we need about 500 mg a day for our bodies to function normally [2]. But in today's world, it's almost unheard of to get to such a low level. While blood levels of sodium that are too low are relatively common in hospitalized patients, they generally are caused by serious health problems, not by eating too little salt [14].
And remember Walter Kempner, the German refugee from our opening? His rice diet — under 230 mg of sodium per day, far below what anyone recommends — ran for nearly 60 years at Duke University, treating over 17,000 patients. When researchers digitized those records, they found even that extreme level appeared safe, with a five-year survival probability of 95.6% [15].
For most of us, our problem is on the other end of the spectrum. The global average sodium intake is nearly 4,000 mg/day [13]. Worrying about the salt recommendations because it's possible to have too little is like pushing back against exercise guidelines because it's possible to over-train and cause injury.
Practical Takeaways
So let's get really practical. What are the takeaways?
First, for most of us, the guidelines presented by the WHO and the American Heart Association make good sense. They are backed up by the best evidence we have to date. Keeping our sodium intake low is linked to lowered blood pressure. And that, in turn, is linked to lower risks for a number of problems connected to heart health.
Okay, but should we shoot for 2,300? Or 2,000? Or even 1,500 mg of sodium a day?
Mente has pointed out how extreme the lowest targets are. Authors of a journal article proposed using prison populations to study the effects of lower intakes because adults find it very difficult to cut their sodium consumption to the 1,800 to 2,300 mg/day range [16]. Mente commented, "The fact that a prison population is proposed as a way to make the study feasible just really strongly speaks to how off the charts the current recommendations are" [17].
Here's the honest answer. For most of us, the lower our sodium intake, the better.
We do have substantial evidence that we continue to reap benefits in terms of blood pressure reduction as we lower our consumption. An earlier meta-analysis found the relationship holds at both the high and low ends of the spectrum of sodium consumption [18].
And when it comes to cutting back on sodium intake, it's helpful to realize most of the salt we consume isn't what we add at home. It's from packaged foods, which often contain very high levels [19]. So cutting back on those is an easy way to reduce intake. And it will help us shift to much healthier whole foods at the same time.
Even a little change can go a long way. A recent study in China had people switch out regular salt for a salt substitute. Instead of standard table salt, which is 100% sodium chloride, the salt substitute was 75% sodium chloride and 25% potassium chloride [20].
That little dietary tweak cut stroke risk by 14%, a combined measure of major heart problems and strokes by 13%, and risk of death by 12% over not quite 5 years of follow up. Average blood pressure among those using the salt substitute dropped 3.34 points [20].
Lead investigator Bruce Neal put the scale of the impact in perspective: About 10 million major cardiovascular events happen each year in China. About 1 million of those could be avoided by this single change. One swap in the salt shaker. A million fewer heart attacks and strokes [21].
A salt substitute is a great intervention because it actually kills two birds with one stone. It cuts sodium intake and, at the same time, increases potassium intake. And here's something really fascinating. A follow-up analysis found that the majority of the blood pressure reduction in that China study came from the addition of potassium, not the subtraction of sodium [22].
Ideally, we'll want to both keep sodium intake low and boost potassium. But because most of us don't get very much potassium in our diets, increasing our intake is an easy win.
A meta-analysis on potassium and blood pressure shows just how significant the impact can be. When daily potassium intake reached 3,500 to 4,700 mg, the blood pressure reduction was an amazing 7.16 mmHg [23].
So potassium intake is critical in balancing sodium in our systems. And we want to prioritize natural food sources like leafy green vegetables, beans, lentils, and bananas. But we also need to keep in mind the risks with too much potassium for people with kidney disease.
So remember Walter Kempner's patient from 1942 — the woman who was supposed to die? She survived because of something as simple as changing what she ate. Eighty years of research since then has only reinforced what Kempner stumbled onto by accident: for most of us, less salt means lower blood pressure and a longer life. The skeptics are right that not everyone responds equally — but the global average intake is nearly double what the evidence supports. Cut back on packaged foods, switch to a potassium-enriched salt substitute, and eat more leafy greens.
How Much Salt Should You Actually Be Eating?
Salt recommendations depend on your blood pressure, medications, and kidney function. Get personalized dietary guidance based on your health profile.
Try Health Roadmap — FreeReferences
1. https://www.drmcdougall.com/education/information-all/walter-kempner-mdfounder-of-the-rice-diet/
3. https://www.who.int/news-room/fact-sheets/detail/sodium-reduction
4. https://www.bmj.com/content/297/6644/319
5. https://pmc.ncbi.nlm.nih.gov/articles/PMC5742671/
6. https://pmc.ncbi.nlm.nih.gov/articles/PMC5098805/
7. https://pmc.ncbi.nlm.nih.gov/articles/PMC4393342/
8. https://www.nejm.org/doi/full/10.1056/NEJMoa1311889
10. https://www.medscape.com/viewarticle/824749
12. https://academic.oup.com/ckj/article/18/7/sfaf173/8177122
13. https://pmc.ncbi.nlm.nih.gov/articles/PMC12624901/
14. https://www.ncbi.nlm.nih.gov/books/NBK470386/
15. https://pmc.ncbi.nlm.nih.gov/articles/PMC11773661
16. https://www.ahajournals.org/doi/10.1161/HYPERTENSIONAHA.118.11103
17. https://www.tctmd.com/news/faulting-salt-new-pure-analysis-argues-against-low-sodium-intake
18. https://pmc.ncbi.nlm.nih.gov/articles/PMC8055199/
19. https://pmc.ncbi.nlm.nih.gov/articles/PMC9962803/
20. https://www.nejm.org/doi/full/10.1056/NEJMoa2105675
21. https://www.tctmd.com/news/massive-ssass-study-shows-switch-salt-substitute-cuts-stroke-cvd
