Winter squash, sweet potatoes, white beans and bananas are some of the richest sources of dietary potassium. These foods contain between 400 and 900 milligrams of potassium per serving. An average adult needs about 4,700 milligrams of potassium daily.
Potassium is found in high quantities in starchy vegetables, greens and legumes. Some vegetable sources of potassium include broccoli, beet greens and acorn squash. One cup of cooked broccoli contains about 475 milligrams of potassium. Half a cup of beet greens contains about 644 milligrams of potassium. Tomatoes contain higher levels of potassium when they are cooked or processed into sauce - one quarter-cup of tomato paste has about 664 milligrams of potassium.
Other sources of potassium include some dairy products, meat and seafood. One cup of fat-free yogurt contains roughly 579 milligrams of potassium, while a cup of 1 percent milk contains about 366 milligrams. In dairy products, a lower fat content generally equals a higher potassium content.
Three ounces of cooked pork tenderloin contain about 382 milligrams of potassium, while three ounces of cooked chicken breast have roughly 218 milligrams. Three ounces of cooked halibut have 490 milligrams of potassium. Salmon and tuna are also sources of dietary potassium, with 326 and 201 milligrams per three-ounce serving, respectively.