Many fruits and vegetables are good sources of potassium, but there are some conditions, like kidney or heart failure, that require a diet low in potassium. Some fruits and vegetables that are low in potassium (with less than 100mg of potassium in ½ a cup) are: Applesauce, blueberries, cranberries, lemon or lime (½ medium), pears, cabbage, cucumber, green beans, leeks, iceberg lettuce, water chestnuts and bamboo shoots.
Potassium is required for every cell in the body to function normally. It is needed for normal heart rhythm and normal blood pressure. It is involved with fluid balance, normal muscle growth, and regulation of acid levels in the body.