The main job of the kidneys is to clean your blood of excess fluids and waste products. When functioning normally, these fist-sized powerhouses can filter 120–150 quarts of blood each day, producing one to two quarts of urine. This helps prevent waste buildup in the body. It also helps keep electrolytes, such as sodium, phosphates, and potassium at stable levels.
People with kidney disease have diminished renal function. They’re typically unable to regulate potassium efficiently. This can cause hazardous levels of potassium to remain in the blood. Some medications used to treat kidney disease also raise potassium, which can add to the problem.
High potassium levels usually develop slowly over weeks or months. This can lead to feelings of fatigue or nausea.
If your potassium spikes suddenly, you may experience difficulty breathing, chest pain, or heart palpitations. If you begin experiencing these symptoms, call your local emergency services. This condition, called hyperkalemia, requires immediate medical care.
One of the best ways to reduce potassium buildup is to make dietary changes. To do that, you’ll need to learn which foods are high in potassium and which are low. Be sure to do your research and read the nutritional labels on your food.
Keep in mind that it isn’t just what you eat that counts, but also how much you eat. Portion control is important to the success of any kidney-friendly diet. Even a food that’s considered low in potassium can spike your levels if you eat too much of it.
Foods to add to your diet
Foods are considered low in potassium if they contain 200 milligrams (mg) or less per serving.
Some low-potassium foods include:
- berries, such as strawberries and blueberries
- cranberries and cranberry juice
- green beans
- white rice
- white pasta
- white bread
Foods to limit or avoid
Foods are considered high in potassium if they contain more than 200 mg per serving. These should be eaten in very small quantities, or avoided completely.
Limit high-potassium foods such as:
- prunes and prune juice
- oranges and orange Juice
- tomatoes, tomato juice, and tomato sauce
- Brussels sprouts
- split peas
- potatoes (regular and sweet)
- dried apricots
- brown or wild rice
- whole wheat products, including pasta and bread
- bran products
- low-sodium cheese
If you can, swap canned fruits and vegetables for their fresh or frozen counterparts. The potassium in canned goods leaches into the water or juice in the can. If you use this juice in your meal or drink it, it can cause a spike in your potassium levels.
The juice usually has a high salt content, which will cause the body to hold onto water. This can lead to complications with your kidneys. This is also true of meat juice, so be sure to avoid this, too.
If you only have canned goods on hand, be sure to drain the juice and discard it. You should also rinse the canned food with water. This can reduce the amount of potassium you consume.
If you’re cooking a dish that calls for a high-potassium vegetable and you don’t wish to substitute, you can actually pull some of the potassium from the veggie.
The National Kidney Foundation advises the following approach to leaching potatoes, sweet potatoes, carrots, beets, winter squash, and rutabagas:
- Peel the vegetable and place it in cold water so that it won’t darken.
- Slice the vegetable into 1/8-inch-thick parts.
- Rinse it in warm water for a few seconds.
- Soak the pieces for a minimum of two hours in warm water. Use 10 times the amount of water to the amount of vegetable. If you soak the vegetable for longer, be sure to change the water every four hours.
- Rinse the vegetable under warm water again for a few seconds.
- Cook the vegetable with five times the amount of water to the amount of vegetable.
People with functioning kidneys need around 4,700 mg of potassium in their daily diet. However, people with chronic kidney disease (CKD) should consume much less — around 1,500 to 2,700 mg each day.
If you have CKD, you should have your potassium checked once a month by your doctor. They’ll do this with a simple blood test. The blood test will determine your monthly level of potassium millimoles per liter of blood (mmol/L).
The three levels are:
- Safe zone: 3.5 to 5.0 mmol/L
- Caution zone: 5.1 to 6.0 mmol/L
- Danger zone: 6.0 mmol/L or higher
Your doctor can work with you to determine how much potassium you should ingest daily, while also maintaining the highest level of nutrition possible. They’ll also monitor your levels to ensure that you’re staying within a safe range.
People with high potassium levels do not always have symptoms, so being monitored is important. If you do have symptoms, they may include:
- numbness or tingling
- chest pain
- irregular pulse
- erratic or low heartbeat
If you have kidney disease, meeting your nutritional needs may be easier than you think. The trick is getting the hang of what you can eat and what you should reduce or remove from your diet.
Eating smaller portions of protein, such as chicken and beef, is important. A protein-rich diet can cause your kidneys to work too hard. Reducing your protein intake by practicing portion control may help.
Sodium may increase thirst and lead you to drink too many fluids, or cause bodily swelling, both of which are bad for your kidneys. Sodium is a hidden ingredient in many packaged foods, so make sure to read the labels. Instead of reaching for the salt to season your dish, opt for herbs and other seasonings that don’t include sodium or potassium.
You’ll also likely need to take a phosphate binder with your meals. This can prevent your phosphorus levels from getting too high. If these levels get too high, it can cause an inverse drop in calcium, leading to weak bones.
You may also consider limiting your cholesterol and total fat intake. When your kidneys don’t filter effectively, eating foods heavy in these components is harder on your body. Becoming overweight due to a poor diet can also put added stress on your kidneys.
You may find eating out to be challenging at first, but you can find kidney-friendly foods in almost every type of cuisine. For example, grilled or broiled meat and seafood are good options at most American restaurants. You can also opt for a salad instead of a potato-based side like fries, chips, or mashed potatoes.
If you’re at an Italian restaurant, skip the sausage and pepperoni. Instead, stick to a simple salad and pasta with non-tomato-based sauce. If you’re eating Indian food, go for the curry dishes or Tandoori chicken. Be sure to avoid lentils.
Always request no added salt, and have dressings and sauces served on the side. Portion control is a helpful tool. You can usually order child-sized portions if the food is too high in sodium or potassium.
Some cuisines, such as Chinese or Japanese, are generally higher in sodium. Ordering in these types of restaurants may require more finesse. Choose dishes with steamed, instead of fried, rice. Don’t add soy sauce, fish sauce, or anything containing MSG into your meal.
Deli meats are also high in salt and should be avoided.
If you have kidney disease, reducing your potassium intake will be an important aspect of your day-to-day life. Your dietary needs may continue to shift and will require monitoring if your kidney disease progresses.
In addition to working with your doctor, you may find it helpful to meet with a renal dietitian. They can teach you how to read nutrition labels, watch your portions, and even plan out your meals each week.
Learning how to cook with different spices and seasonings can help you reduce your salt intake. Most salt substitutes are made with potassium, so they are off limits.
You should also check in with your doctor about how much fluid to take in each day. Drinking too much liquid, even water, may tax your kidneys.