The best sources of potassium are not bananas. While bananas get all the credit, cooked leafy greens, beans, potatoes, and squash deliver far more potassium per serving. A single cup of cooked beet greens contains 1,309 mg of potassium, nearly three times what you’d get from a medium banana. Adults need roughly 2,600 to 3,400 mg per day, and most people fall short.
The Highest Potassium Foods by Serving
USDA data on standard serving sizes paints a clear picture: dark leafy greens and starchy root vegetables dominate the list. Here are the top sources:
- Beet greens, cooked (1 cup): 1,309 mg
- Swiss chard, cooked (1 cup): 961 mg
- Lima beans, cooked (1 cup): 955 mg
- Baked potato with skin (1 medium): 926 mg
- Yam, cooked (1 cup): 911 mg
- Acorn squash, cooked (1 cup): 896 mg
- Spinach, cooked (1 cup): 839 mg
Notice a pattern: cooking concentrates these greens significantly. A cup of raw spinach weighs about 30 grams, but a cup of cooked spinach represents several cups’ worth of raw leaves wilted down. That concentration is what pushes the potassium numbers so high. You’d struggle to eat enough raw spinach to match a single cup of cooked.
Beyond Fruits and Vegetables
Most people think of potassium as something found in fruits. In reality, legumes and starchy staples are among the richest sources. A cup of cooked lima beans delivers 955 mg, roughly a third of most adults’ daily target from one side dish. Other beans, lentils, and split peas follow a similar pattern, typically landing between 400 and 700 mg per cup.
Potatoes deserve special attention. A single medium baked potato with the skin on provides 926 mg. That’s more than twice a banana, and it’s a food most people already eat regularly. The key is keeping the skin on, since a significant share of the potassium sits just beneath it. Sweet potatoes, yams, and plantains are similarly rich.
Fish, dairy, and meat also contribute meaningful amounts. A serving of salmon or halibut typically provides 300 to 500 mg. Yogurt lands in a similar range. These foods won’t top the charts individually, but they add up over a full day of eating, especially for people who don’t eat large volumes of vegetables.
Why Your Body Needs Potassium
Potassium’s most important job is regulating blood pressure, and it does this through a surprisingly direct mechanism. Your blood vessels are lined with smooth muscle cells that contract or relax to control blood flow. Potassium stimulates a pump in those cells that moves sodium out, which causes the muscle to relax and the blood vessel to widen. Wider vessels mean lower blood pressure.
This process also reduces calcium flowing into the vessel walls, which further prevents them from tightening. On top of that, potassium helps clear norepinephrine (a stress hormone that constricts blood vessels) from nerve endings around your arteries, giving your blood vessels yet another reason to relax. People with salt-sensitive blood pressure tend to see the biggest benefit from increasing potassium intake, partly because potassium also helps your kidneys excrete more sodium through urine.
Beyond blood pressure, potassium is essential for nerve signaling and muscle contraction, including the electrical impulses that keep your heart beating in rhythm. When levels drop too low, the earliest symptoms are usually muscle cramps, fatigue, and constipation.
How Well Your Body Absorbs It
One reason food sources work so well is that your body absorbs 85% to 90% of the potassium you eat. That’s a high absorption rate compared to many other minerals. There’s no need to pair potassium foods with specific nutrients to boost uptake the way you might with iron or calcium.
A few things can interfere with absorption. Inflammatory bowel conditions like Crohn’s disease increase potassium secretion in the colon, which can lead to low levels even with adequate intake. Chronic diarrhea or heavy vomiting can also deplete potassium quickly, since the body loses it through fluid loss.
Potassium Needs During Exercise
You lose potassium in sweat, and the amount scales with intensity. Trained endurance athletes lose roughly 360 mg per hour during low-intensity exercise, 485 mg per hour at moderate intensity, and about 580 mg per hour during high-intensity sessions. That’s a 60% increase from easy to hard effort.
For a two-hour hard workout, that’s over 1,100 mg of potassium gone through sweat alone. This is one reason athletes sometimes experience muscle cramping late in long training sessions. A post-workout meal built around potatoes, beans, or leafy greens replenishes those losses more effectively than most sports drinks, which tend to prioritize sodium over potassium.
Signs of Low Potassium
Normal blood potassium falls between 3.5 and 5.0 mEq/L. Levels between 3.0 and 3.5 mEq/L qualify as mild hypokalemia, which often causes no obvious symptoms or just mild muscle weakness and fatigue. Below 3.0 mEq/L is considered severe and can cause dangerous heart rhythm problems, significant muscle weakness, and in extreme cases, paralysis.
Most healthy people who eat a varied diet won’t develop clinically low potassium. The bigger concern is chronic under-consumption: consistently getting less than your body needs without dropping low enough to trigger obvious symptoms. Over years, this pattern is associated with higher blood pressure and greater cardiovascular risk.
Who Should Be Careful With Potassium
For people with healthy kidneys, it’s difficult to get too much potassium from food alone. Your kidneys efficiently filter excess potassium and excrete it through urine. The concern shifts dramatically for people with chronic kidney disease, whose kidneys lose the ability to regulate potassium levels. In that situation, high-potassium foods can cause dangerous spikes in blood levels, and intake needs to be carefully managed with the help of a dietitian.
The National Kidney Foundation classifies foods with more than 200 mg per serving as “higher potassium” foods. For people managing kidney disease, that threshold helps guide daily choices. For everyone else, those higher-potassium foods are exactly what you should be eating more of.
Practical Ways to Get Enough
Getting adequate potassium doesn’t require exotic ingredients. A baked potato at lunch (926 mg), a cup of cooked spinach at dinner (839 mg), and a cup of yogurt as a snack (around 400 mg) puts you past 2,100 mg before counting anything else you ate that day. Add beans to a soup or swap white rice for cubed acorn squash, and you’re close to a full day’s worth.
Cooking method matters less than you might expect. While boiling vegetables does leach some potassium into the water, you retain it if you use that liquid, as in soups or stews. Roasting, baking, and steaming preserve potassium well. The biggest practical lever is simply eating more whole foods and fewer processed ones, since food processing tends to remove potassium and add sodium, exactly the opposite of what most people’s bodies need.