By the time most of us hit middle age, we’ve learned to keep an eye on salt. Doctor’s orders. High sodium, after all, is a known contributor to the silent killer — hypertension. But what if a humble nutrient found in bananas, beans, and spinach quietly does more than we ever imagined to shield our hearts?

A new study led by Melissa Stadt and Anita T. Layton at the University of Waterloo reveals that potassium doesn’t just counterbalance salt’s harmful effects. It may rewire the body’s entire blood pressure system — and it does so differently in women and men.

A Tale of Two Electrolytes

High blood pressure — also known as hypertension — affects more than 1 in 3 adults worldwide. It’s the primary driver of heart disease and stroke, and it plays a role in kidney failure, heart rhythm disorders, and even dementia. But despite decades of public health campaigns, rates remain stubbornly high.

Dr. Layton believes it’s time to look beyond sodium alone.

“Usually, when we have high blood pressure, we are advised to eat less salt,” said Layton, who also holds the Canada 150 Research Chair in Mathematical Biology and Medicine. “Our research suggests that adding more potassium-rich foods to your diet, such as bananas or broccoli, might have a greater positive impact on your blood pressure than just cutting sodium.”

Sodium and potassium are both electrolytes that keep our muscles working and our bodies hydrated. But they play opposite roles in the regulation of blood pressure. Sodium tends to raise it. Potassium tends to lower it.

Over evolutionary time, our bodies may have adapted to a very different balance than the one we live with today.

“Early humans ate lots of fruits and vegetables, and as a result, our body’s regulatory systems may have evolved to work best with a high potassium, low sodium diet,” said Melissa Stadt, a PhD candidate in the Department of Applied Mathematics at Waterloo and the lead author of the study. “Today, western diets tend to be much higher in sodium and lower in potassium. That may explain why high blood pressure is found mainly in industrialized societies, not in isolated societies.”

Modeling the Modern Diet

Using a detailed mathematical model of the human body, the researchers simulated how varying levels of potassium and sodium affect the cardiovascular system. Their model simulates how sodium (Na⁺), potassium (K⁺), fluid, hormones, and nerves interact across five major systems: the kidneys, cardiovascular system, gastrointestinal tract, endocrine system, and sympathetic nervous system.

With this, they didn’t just run a single scenario. They played out dozens. What happens when sodium doubles? What if potassium spikes at the same time? What if a man and a woman eat the exact same salty meal — who reacts more strongly?

These simulations offered a clearer view of how the ratio between the two electrolytes influences blood pressure.

The model also uncovered something unexpected: sex matters.

Men, the study found, are more susceptible to developing high blood pressure than pre-menopausal women. But paradoxically, they may also see a greater benefit from improving their potassium-to-sodium ratio. Women’s kidneys are less aggressive in reclaiming sodium from urine, which means they naturally excrete more of it — giving them a leg up in regulating blood pressure.

This insight could guide more personalized dietary recommendations in the future.

Layton and Stadt argue that mathematical modeling offers a powerful way to test biological hypotheses without the high costs — or ethical concerns — of clinical trials. It allows scientists to explore variables that would be impossible to isolate in real-world studies.

“These kinds of experiments identify how different factors impact the body quickly, cheaply, and ethically,” the researchers noted.

What Should We Do?

So what does this mean for the average person standing in the grocery store?

Most experts agree we still eat too much sodium. But instead of just obsessing over salt shakers and nutrition labels, people might consider what’s missing from their diets.

Adding potassium-rich foods like leafy greens, beans, sweet potatoes, and yes, bananas, could shift the balance in your favor.

For scientists like Layton and Stadt, the bigger lesson is that our bodies evolved in a very different dietary world. Understanding that mismatch — and how to fix it — may be the key to fighting one of the world’s deadliest chronic conditions.

The findings appeared in the American Journal of Physiology-Renal Physiology.