When it comes to heart health, some electrolytes are controversial. Others, not so much.
Potassium is not controversial. Higher potassium intakes are unarguably linked to lower blood pressure. Since high blood pressure is a primary factor contributing to heart disease risk, we like that.
Here’s what the FDA says about potassium:
“Diets containing foods that are a good source of potassium and that are low in sodium may reduce the risk of high blood pressure and stroke.”
Wait... did you catch the low in sodium part? Here’s where things DO get controversial.
The US government recommends capping sodium intake at 2.3 grams per day. This is, allegedly, a heart-healthy move. And until the past decade or so—when guys like myself and Chris Kresser started sounding alarm bells—it’s been taken as gospel.
But in the majority of cases, sodium restriction doesn’t do the heart any favors. We have data suggesting that, when sodium intake goes down (under 2.3 grams), bad outcomes like heart attack and stroke go up.
Today I want to cover the clinical research behind electrolytes and heart health. Sodium is the star here, but minerals like potassium and magnesium play important roles too in heart function, blood pressure, and more.
Later, I’ll give recommendations for electrolyte intake through diet and supplementation. Most people aren’t getting enough, and I’d like to see that change.
Of course, I’ll never have the pull that the FDA has. But maybe if I squawk loudly and frequently enough, it’ll start a groundswell. And that groundswell will slowly shift the anti-salt sentiment.
But how did this sentiment start?
Why Low Sodium Is Considered “Heart Healthy”
Most people haven’t heard of Lewis Dahl. He was a scientist that ran a number of sodium-related studies back in the 60s and 70s.
His most famous experiments featured rats (now called “Dahl rats”) that were genetically prone to salt sensitivity. When Dahl fed these rats high-sodium diets, they developed—predictably enough—high blood pressure, or hypertension.
The sodium - blood pressure link appeared to be supported by a smattering of population data. But the data was inconsistent. Many big salt eaters, for instance, weren’t hypertensive. Was it possible that something else (not sodium) was driving the correlation?
The question was never properly addressed. Instead, the 1980 US government began warning its citizens to avoid sodium.
Today these warnings are enshrined in official recommendations. We’re told to consume under 2.3 grams of sodium per day, per the FDA—and even less (1.5 grams) if you heed the American Heart Association’s advice.
And so the salt shaker has become a pariah. Salt has become a public enemy, right up there with sugar and cigarettes.
Is sodium’s reputation deserved? Let’s see what the evidence has to say.
Sodium and Heart Disease Risk
In most hospitals, heart patients are fed low-sodium diets. This is meant to reduce blood pressure, and therefore bad outcomes like heart attack and stroke.
But a 2011 study published in JAMA—one of the most prestigious journals on the planet— suggests this policy is misdirected.
The study followed nearly five thousand patients with preexisting heart disease or diabetes for close to five years. Researchers tracked their sodium excretion (as a proxy for sodium consumption), and compared it with rates of stroke and heart attack after the five-year follow up.
The results should surprise sodium cynics. The patients at the lowest sodium intakes (in line with government recommendations) had higher rates of stroke and heart attack than patients at more moderate intakes of about 5 grams of daily sodium. You had to reach about 8 grams of sodium before the risk spiked up again.
And this result occurred in the very folks—high risk patients—that low-sodium diets are supposed to help. Well, they didn’t help.
I know what you’re thinking. That’s just one study... It doesn’t prove low sodium diets aren’t heart healthy.
That’s right. It’s important to look at systematic reviews—or papers that compile the literature on a given topic.
One such review, published in JAMA in 2018, looked at nine clinical studies that asked one question: Does restricting salt help with heart failure?
Across the literature, the evidence was “inconclusive”. In other words, there isn’t a good case for sodium restriction in heart failure patients.
But what about sodium driving up blood pressure? Surely there’s something to that.
Sodium and Blood Pressure
One of sodium’s primary functions is to increase fluid volume in your blood vessels. This helps get blood to your brain (among other places), and it’s a big reason why low serum sodium brings a host of cognitive symptoms.
So yes. Boost your sodium intake high enough, and you will increase blood volume enough to raise blood pressure.
But how does this play out in the real world, where real people are consuming varying amounts of sodium?
To answer this question we turn to the 1988 Intersalt Study, which analyzed over 10,000 people across the globe to explore the link between dietary sodium and blood pressure. The punchline? In most populations, there was no link between salt consumption and hypertension.
More recent research has strengthened this finding. Researchers wondered: What happens when you take a few thousand people with normal blood pressure, and see where they fall on the sodium intake / blood pressure graph?
The result was a doozy. Those at lower sodium intakes (under 2.5 grams) had HIGHER blood pressure than those at higher sodium intakes. If sodium was driving hypertension, how could this result happen?
Potassium and Blood Pressure
Okay, that was my sodium rant. Now I need to talk about potassium, because it’s all tied up in this blood pressure question.
Potassium, like sodium, helps regulate fluid balance inside and outside your cells. This keeps your blood flowing through your veins, your brain suspended in fluid, and—yes—your blood pressure within healthy ranges.
Higher potassium intakes are uncontroversially associated with lower blood pressure, and the FDA-recommended 4.7 grams per day is a good science-based target. (Hey, they get it right sometimes!).
Only 3% of Americans, however, hit the potassium target. This contributes to higher blood pressure and increased heart disease risk.
And this increased risk is blamed on sodium. Let me explain how.
Think about the Standard American Diet (SAD), infamous for causing the metabolic problems that drive heart disease.
The SAD is a high sodium diet, it’s true. (Processed foods are usually salty foods). But it’s also high in sugar and low in potassium-rich fruits and vegetables.
Here’s a fun fact: People who eat more salt are also more likely to drink sugary beverages. Talk about a confounding factor that makes sodium look bad...
Potassium is the other big confounder. High salt generally means low potassium, which is bad news for blood pressure. But in the context of a high-potassium diet, there’s no evidence that moderate sodium intakes (~5 grams per day) increase the risk of hypertension.
Magnesium and Heart Health
Tribute must now be paid to magnesium, a mineral which literally helps regulate the beating of your heart. Magnesium also influences blood vessel relaxation, calcification, clotting, and even inflammation.
Inflammation is a key driver of atherosclerosis, the process underlying heart disease. Specifically, inflammatory particles like cytokines and macrophages contribute to the formation of plaque in the arteries. When these plaques eventually break off, a heart attack or stroke can occur.
By modulating this immune-driven process, magnesium may modulate heart disease risk. This is evidenced by the fact that magnesium deficient patients have higher levels of systemic inflammation.
Magnesium supplementation is also a promising therapy for alleviating cardiac arrhythmia, a condition in which the heart doesn’t beat properly.
According to one estimate, up to 30% of people are subclinically deficient in magnesium.
But since it’s difficult to assess magnesium status in the blood, I suspect deficiency rates are even higher. These hidden magnesium deficiencies likely contribute to the high rates of heart disease we see in society.
Optimizing Electrolytes For Heart Health
Every electrolyte has a sweet spot for health. Although our best numbers look at population based recommendations, it’s important to note that individual needs and tolerances will be a big factor.
Just as a quick aside: the half life of caffeine (how long it takes the body to metabolize half a dose of caffeine) is, on average, 8 hours. Yet, it is well understood that some people can metabolize the same in 4 hours, while others take 36!
These ranges are still unclear for many electrolytes. So, when it comes to optimal electrolyte amounts and ratios, rest assured — what you need may be different than what your neighbor needs.
For sodium, the sweet spot appears to hang around 5 grams per day. For potassium, it’s about 4.7 grams per day. And for magnesium, it’s around 600 mg per day, based on the diets of hunter/gatherer societies.
Most of your potassium and magnesium should come from dietary sources. This means eating dark leafy vegetables, starchy tubers, meat, and fruits.
If you’re on a low-carb or keto diet, the last two categories are restricted, so you’ll need to double down on dark leafy greens like spinach and kale to get enough electrolytes.
Keto or not, I recommend folks supplement with a gram of potassium and 200 mg magnesium per day in addition to dietary sources. The harder part is hitting 5 grams of sodium, but that seems to be the sweet spot for heart health outcomes, general energy, and wellbeing.
I created LMNT to help folks hit these science-based sodium, potassium, and magnesium targets. And to give people a palatable low-sugar electrolyte option.
In case you were wondering, I didn’t put calcium in LMNT because calcium deficiency is more rare. Plus there’s some evidence that calcium supplements increase arterial calcification.
Anyways, however you get your electrolytes—from diet, LMNT, homebrews, or ad hoc supplements—I hope that you do. Your heart will be healthier for it.