Why do people take potassium?
Most people who eat a healthy diet should get enough potassium naturally. Low potassium is associated with a risk of high blood pressure, heart disease, stroke, arthritis, cancer, digestive disorders, and infertility. For people with low potassium, doctors sometimes recommend improved diets — or potassium supplements — to prevent or treat some of these conditions.

Potassium deficiencies are more common in people who:

Use certain medicines, such as diuretics
Have physically demanding jobs
Athletes exercising in hot climates and sweating excessively
Have health conditions that affect their digestive absorption, such as Crohn’s disease
Have an eating disorder
Smoke
Abuse alcohol or drugs
How much potassium should you take?
The Institute of Medicine has set an adequate intake for potassium. Getting this amount of potassium from diet, with or without supplements, should be enough to keep you healthy. The FDA has determined that foods that contain at least 350 milligrams of potassium can bear the following label: “Diets containing foods that are good sources of potassium and low in sodium may reduce the risk of high blood pressure and stroke.”
There is no set upper limit for potassium. So it’s not clear exactly how much potassium you can take safely. However, very high doses of potassium can be deadly.

Can you get potassium naturally from foods?
Good natural food sources of potassium include:

Bananas
Avocados
Peanuts and tree nuts such as almonds, pecans and walnuts
Citrus fruits
Leafy, green vegetables
Milk
Potatoes
Keep in mind that some types of cooking, such as boiling, can decrease the potassium content in some foods.