The best foods high in potassium — and why you need them

Bananas are just the beginning: almost every food in the plant kingdom, from potatoes to papayas, supplies some amount of potassium.

So, it might be surprising to learn that nutrition experts have flagged the mineral as a nutrient of public health concern. That's because most Americans aren't getting enough, and there's evidence that the risks of some common chronic diseases may rise with inadequate potassium intake. The recommended adequate intake is 3,400 milligrams (mg) per day for adult men and 2,600 mg for adult women, yet surveys suggest many Americans fall short.

Why the gap? Some of it stems from "the same story we've heard before: people aren't eating enough fruits and vegetables, and especially legumes," says Teresa Fung, adjunct professor of nutrition at Harvard's T.H. Chan School of Public Health. Compounding the problem, she adds, is that the modern American diet is heavily weighted toward ultra-processed foods, which are typically low in potassium and high in sodium — the exact opposite of what the body needs.

Furthermore, a study published in the Journal of the American College of Nutrition identified a troubling trend: blood potassium levels in the US population declined measurably between 1999 and 2016, with hypokalemia (low blood potassium levels) rising from about 4% to over 11% during that period. The researchers pointed to declines in potassium content in food crops and rising consumption of processed foods as potential causes. (Severe hypokalemia is rare in the general population and is usually due to underlying disease or certain medications.)

"Potassium is one of those nutrients that's not really on people's radar screens," says Fung. "But it should be."

What does potassium do for the body?

Potassium, like sodium, is an essential electrolyte — a mineral that carries a tiny electrical charge — and every cell in the body depends on it. It helps relax blood vessel walls and signals the kidneys to excrete excess sodium, naturally lowering blood pressure and thus helping to reduce the risk of stroke and cardiovascular disease. A number of studies suggest a potential link between lower intake of potassium and a higher risk of high blood pressure (hypertension), stroke, and other cardiovascular disease. Potassium also works with sodium to generate the electrical signals that enable muscles (including the heart) to contract and relax.

Another reason to seek out foods rich in potassium: These plant foods tend to be high in dietary fiber, which nourishes beneficial gut bacteria. Those bacteria produce compounds that maintain the gut lining and help regulate inflammation — which may play a role in protecting cognitive health.

How to boost your potassium intake

The single most effective strategy to amp up potassium is to eat more whole, minimally processed foods, particularly fruits, vegetables, and legumes, says Fung. A few practical steps:

Get in the legume habit. Beans, peas, and lentils are high-potassium foods, and they also supply a good amount of protein and filling fiber. Try to eat some daily, or at least several times a week. "A half-cup serving isn't hard to do," says Fung; canned beans make it even easier. Add them to salads, soups, tacos, casseroles, and pasta dishes — or try hummus and cut-up vegetables for a potassium-packed snack.

Enjoy potatoes and sweet potatoes, simply cooked and skin on. Both are potassium powerhouses, and a fair amount of the mineral (as well as some fiber) is in or just beneath their skins. "Of course, we're not talking about French fries or potato chips," says Fung, who likes to "quick bake" her spuds in the microwave.

Savor fruit in all forms, including a little juice and dried fruit. Both are good sources of potassium and can help you meet your daily potassium goal — but go easy, says Fung. "Juice is high in sugar, even if it's natural." With dried fruits, the drying process concentrates natural sugars and calories, and many contain added sugars, she adds. "To balance getting some potassium and not too much sugar, have a small glass of 100% fruit juice with no added sugars, or a small amount of dried fruit."

Eat more dark leafy greens. Beet greens, Swiss chard, and spinach all rank among the top sources of potassium per serving. Layer them in sandwiches, toss them with salads and pastas, or arrange them into a bed for an entree.

Increase your intake of dairy and fish. Many are potassium-rich. See "Potassium-rich foods" for details.

Follow a DASH or Mediterranean diet pattern. Both emphasize potassium-rich fruits and vegetables and limit sodium — all good news for your heart health.

Source: USDA FoodData Central.

Image: © Alrphoto/Getty Images