Fish for a Low-Potassium Diet

"People with poor kidney function generally must avoid foods high in potassium."

The Merck Manual of Medical Information could not be any clearer. Adequate amounts of potassium in the diet are crucial because the mineral helps keep blood pressure under control and "has major roles in cell metabolism and in nerve and muscle cell function," according to Merck's.

However, too much potassium in the blood is more dangerous than too little. Numerous fruits and vegetables are on lists of high-potassium foods. People with kidney problems should consider eating healthy fish instead. Add this to my Recipe Box.

Medical Checkup

You should ask your doctor to test your blood and give you an electrocardiogram if you have Addison's disease, because the illness can cause high potassium levels, or hyperkalemia.

An irregular heartbeat can also be a symptom of hyperkalemia, but the condition often has no symptoms when it is mild.

High-Potassium Foods

You should stop eating foods that are very high in potassium if you are diagnosed with hyperkalemia.

"The Well Adult" lists 16 foods on its "High-Potassium" foods list. The fruits on the list are apricots, bananas, dates, figs, melons, oranges, prunes, and raisins. Legumes and vegetables on the list are beans, mushrooms, peas, potatoes, spinach, sweet potatoes, tomatoes and winter squash.

The smaller list in Merck's includes bananas, beans, melons, oranges, peas, potatoes, spinach and tomatoes.

High-Potassium Fish

You should reduce the amount of shellfish you eat if you have too much potassium in your blood.

Fish is generally a high-potassium food with at least 300 milligrams in a serving size. Shellfish, in particular, has a high amount of the mineral. "Nutripoints: A New Guide to Simple, Healthy Eating," warns readers to stay away from oysters and clams.

Low-Potassium Foods

You should stick to a diet with fewer than 2,000 milligrams of potassium per day if you have hyperkalemia. Foods with fewer than 100 milligrams per serving size are considered low-potassium foods.

Fish is rarely on the list of low-potassium foods, although a few nutritionists put tuna on their lists. Very low-potassium foods include applesauce, blueberries, bread, cheese, corn, grapes and pasta. Other foods listed on low-potassium lists include apples, blackberries, cherries, grapefruit, rice, pineapple, raspberries, strawberries and tangerines.

Healthful Fish

You should consider eating more healthful fish as a replacement for otherwise healthful fruits and vegetables if your potassium levels are too high.

Meats are not on most high- or low-potassium food lists, but they generally are less healthful than fish because of their saturated-fat content. Fish high on the "Nutripoints" list of healthful foods include tuna fish, baked pike, steamed and poached salmon, baked halibut, baked red snapper and baked freshwater bass.