Boosting Potassium, Not Just Cutting Sodium, May Be the Best Way to Lower Blood Pressure

Adding more potassium to your diet could be an easier, more effective way to lower blood pressure than cutting salt alone, new research finds.

The study, published in the American Journal of Physiology–Renal Physiology, builds on what scientists have long understood: That sodium and potassium work together to regulate blood pressure.

“Usually, when we have high blood pressure, we are advised to eat less sodium,” study author Anita Layton, PhD, a professor of applied mathematics, computer science, pharmacy, and biology at the University of Waterloo in Canada, told Health.

The new research, however, “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,” Layton said in a news release.

For the study, Layton and her team dug into how the ratio of potassium to sodium impacts the body.

Using a mathematical model, the study authors simulated how different sodium-to-potassium ratios affected bodily systems, including the renal system (kidneys), cardiovascular system, and gastrointestinal system. “I basically used math as my microscope,” said Layton.

Ultimately, researchers found more dietary potassium helped lower blood pressure, even with “high” or “normal” levels of sodium intake—whenever potassium went up, regardless of sodium levels, blood pressure went down.

The researchers also discovered a notable difference when they adjusted for sex in the mathematical models: Men were more likely to have a greater reduction in blood pressure after increasing their potassium-to-sodium ratio than premenopausal women. (That’s a key differentiator because blood pressure tends to tick up after menopause.) 

Researchers say, however, that it’s important to take these findings with a grain of salt: Computer models are a fast, inexpensive, and ethical way of simulating the human body, but Layton stressed they are an “approximation of physiology.”

An understanding of the balance of sodium and potassium in the body and its effects on heart health isn’t necessarily new.

When you consume too much sodium, more water gets drawn into your blood vessels, swelling their blood volume. This makes your blood pressure increase, which can damage the vessels’ walls and lead to the buildup of plaque in your arteries. This stunts healthy blood flow and stresses your heart over time.

Potassium has the opposite effect: It relaxes the walls of your blood vessels, reducing the tension in your arteries so blood can circulate more easily, said Michelle Routhenstein, RD, a preventive cardiology dietitian at Entirely Nourished, a nutrition counseling and consulting practice. (Routhenstein was not involved in the new study.)

“One of the ways sodium and potassium work in tandem is through the kidneys,” Routhenstein told Health. Your kidneys have specialized proteins, called transporters, that use potassium to funnel sodium out of your body through your urine. Basically, the more potassium you eat, the less sodium you retain.

Potassium supplements carry potential safety risks, so getting potassium through food is the way to go, said Layton and Routhenstein.

The FDA set potassium’s daily value at 4,700 milligrams, while the American Heart Association recommends a daily intake of 3,500 to 5,000 milligrams to treat high blood pressure.

Most adults don’t get anywhere close to that amount, said Routhenstein. (At a minimum, men should aim for at least 3,400 milligrams of potassium per day, while women should shoot for at least 2,600 milligrams.)

Bananas get all the glory, with one medium fruit serving up 422 milligrams of potassium. However, there are many other potassium-rich foods that can help you lower blood pressure, like apricots, lentils, baked potatoes, spinach, and salmon.

There’s no “golden” potassium-to-sodium ratio that’s recommended for everyone. Your health history, lifestyle, and dietary needs all play a role in how much of each mineral you should eat per day, said Routhenstein.

The American Heart Association suggests limiting daily sodium intake to 1,500 to 2,300 milligrams, especially if you have high blood pressure. (Pair that with 4,700 milligrams of potassium, and you’re looking at double the potassium to sodium, or a 2:1 ratio.) 

This may be easier for some people than others. For example, if you order most of your meals, it’ll take more time and effort to make lasting changes.

“I’ve helped many people get off their blood pressure medication while they’re only going out to eat,” said Routhenstein. “In those situations, the potassium is where we focus first because we have more ability to control that.” 

Working with a registered dietitian who specializes in heart disease can help you figure out what works best for you.

If you want to start making small changes on your own, here are a few tips to help you work toward your ideal balance:

• Limit your daily sodium to 2,300 milligrams. Do your best to spread your intake throughout the day, rather than eating it all at once.
• Increase your potassium—slowly. Many potassium-rich foods are also high in fiber, and too much of that too quickly can cause GI distress like gas and bloating, and maybe even dramatic shifts in your blood pressure.
• Make one potassium-rich swap for each meal. For breakfast, swap strawberries for bananas; at lunch, use spinach instead of iceberg lettuce; and at dinner, add kidney beans or lentils.

Remember, your diet also needs to be enjoyable for it to stick. “It should be personalized because trying to make changes quickly is not sustainable,” said Routhenstein. “And with heart health, you need to have a long-term game plan.”