In 2007, according to the National Kidney and Urologic Diseases Information Clearinghouse, 527,283 adults in the United States had end-stage kidney disease requiring treatment, most from complications of either diabetes or high blood pressure. If you have kidney disease, medically termed renal disease, you may need to limit your potassium intake because your kidneys can no longer adequately filter potassium out of the blood. Potassium can build up, causing a potentially life-threatening complication called hyperkalemia.
If you have end-stage kidney disease, you need to see your doctor regularly. He or a dietitian trained in treating renal patients will set a daily potassium limit for you, since every person has different requirements. In general, renal patients should restrict their potassium intake to between 1,500 and 2,700 mg of potassium per day, reports the UpToDate website. The dietary recommendation for potassium is 4,700 mg per day for adult Americans, the site notes, so cutting potassium intake requires dietary changes for most people.
The goal of dietary potassium restriction is to keep the blood levels of potassium within normal limits. Serum potassium levels normally range between 3.5 to 5 milliequivalents per liter, or mEq/L. A level over 6 mEq/L can cause dangerous heart arrhythmias, but you can have a dangerously high potassium level with no noticeable symptoms.
Foods considered high in potassium contain more than 250 mg per serving. Foods in this category include many dairy products; most beef products; many types of seafood, including lobster, salmon and scallops; beans and legumes; whole-grain breads; and some fruits and vegetables. Avoid salt-substitutes, which contain large amounts of potassium. Vegetables high in potassium include potatoes and tomatoes, while fruits high in potassium include bananas, oranges, dried fruits and avocados. Low-potassium choices include poultry, tuna, eggs, apples, many berries, carrots, corn and white bread. Soaking vegetables in water for two hours and discarding the water helps leach out potassium, but this may still not lower potassium sufficiently to allow you to eat them frequently.
Nearly all foods contain some potassium. When you have potassium restrictions, you still need to get an adequate amount of protein, vitamins and minerals in your diet, which is why you need to work with your doctor or dietitian to design a diet that supplies your needs while keeping potassium levels under control. You can limit your potassium intake not only by avoiding foods highest in potassium but also by limiting portion sizes. Eating a large amount of even a low-potassium food can raise your potassium intake to unsafe levels.