If you have chronic kidney disease (CKD), choosing the right foods is one of the most important ways you can take control of your condition. That means making sure you’re getting the right amounts of nutrients like protein. One very important nutrient to watch for in your food is potassium, especially if your doctor has told you that you have hyperkalemia (high levels of potassium).
As a nephrologist, I tell my patients there’s a very good reason we focus on potassium, especially when a patient has advanced kidney disease. To understand why, it helps to know more about potassium and the kidneys.
Potassium highs and lows
Potassium is a mineral we can’t live without. It helps our muscles and nerves work well. It also helps our bodies regulate blood pressure. However, when you have CKD, your kidneys can’t remove excess potassium as well as they once did. If you continue to eat foods high in potassium, you are now putting potassium into your body faster than your kidneys can eliminate it. As a result, extra potassium can build up in your blood.
Without treatment, a high potassium level can disrupt your heart’s electrical signals and cause abnormal heart rhythms, called cardiac arrhythmias. Some arrhythmias can be life-threatening. Having a high potassium level can also cause muscle weakness or even paralysis.
Another reason people with CKD may have high potassium levels: Some of the medications we often prescribe to help slow the progression of CKD can cause high or low potassium as a side effect. Three examples are ACE (angiotensin-converting enzyme) inhibitors, Angiotensin Receptor Blockers (ARBs), and mineralocorticoid receptor (MR) antagonists. These medicines can reduce the risk of kidney failure, but they may boost potassium levels.
It’s also important to note that people with CKD are also at risk for low potassium levels (hypokalemia). That can also be a problem. The condition can cause abnormal heart rhythms and other complications. Low potassium sometimes has underlying causes—for instance, adrenal gland disorders, such as hyperaldosteronism.
Recognize the signs
A potassium imbalance doesn’t always cause symptoms. But it’s important to know the possible signs and symptoms of both high and low potassium.
High potassium can cause:
- Muscle weakness
- Numbness or tingling
- Heart palpitations
- Shortness of breath
Low potassium can cause:
- Fatigue
- Constipation
- Muscle weakness
- Heart palpitations
- Muscle cramps
Should you restrict your potassium?
That’s a question for your doctor. Not everyone with CKD needs a low-potassium diet. In fact, if you have mild CKD, a high-potassium diet can actually be beneficial, because it helps lower blood pressure. (High blood pressure can damage the kidneys.)
Regular bloodwork can help your nephrologist and care team keep track of how your kidneys are working and if your potassium is too high or too low. That can help guide your diet and empower you to make any changes you need. In general, we might consider restricting potassium when levels exceed 5.2 or 5.3 millimoles per liter (mmol/L). Your doctor may also prescribe medicines to help lower potassium.
What to eat to manage potassium levels
When I recommend that my patients limit their potassium, they often ask: “What can I eat?”
The challenge is that foods we often think of as “healthy” can be high in potassium. Some examples are greens, beans, coconut water, fruits and fruit smoothies, whole wheat breads, and cereals. You shouldn’t avoid healthy foods just because they contain potassium, but it’s important to limit how often you consume high-potassium foods.
I recommend working with a Temple dietitian for individualized advice about eating well with CKD. In addition, here are four helpful strategies:
1. Know which foods are high and low in potassium
Never isn’t a word I typically use with my patients. Instead, I encourage a balanced approach. That means eating more of the foods that help them manage their CKD, while limiting the ones that don’t.
To help my patients get started, I often review with them examples like these, from the National Kidney Foundation, of high- and low-potassium food choices.
High-potassium foods include:
- Fruits: Avocados; bananas; melons (cantaloupe and honeydew); oranges, mangos; papayas; kiwifruits; prunes; and dried fruits, like dates and figs
Vegetables: Broccoli, brussels sprouts, sweet potatoes, parsnips, pumpkin, vegetable juices, potatoes (including French fries), winter squash, and tomato-based products
- Legumes: Peas, lentils, and beans (dried, black, baked and refried)
- Dairy and other: Milk, yogurt, nuts and seeds, and bran products
Low-potassium foods include:
- Fruits: Apples, grapes, tangerines, blueberries, raspberries, canned peaches and pears, and pineapples
- Vegetables: Asparagus, cabbage, celery, corn, cucumber, eggplant, green or wax beans, green peas or beans, iceberg lettuce, onions, radishes, turnips, and raw tomato (one to two slices)
- Starches: Rice, noodles, pasta, and bread
2. Be mindful of salt substitutes
Many foods marketed as low-sodium use potassium chloride as a substitute. Some salt substitutes for use at home also fall into this category. This substitution can cause harm to people who are trying to limit potassium.
Instead of using salt or salt substitutes, try seasoning foods with
- Lemon juice
- Ground pepper
- Fresh garlic
3. Remove some of the potassium from your favorite foods
You may be able to enjoy your favorite high-potassium vegetables—like potatoes—by slicing them thinly and then pre-soaking them in water before you cook them. A dietitian can tell you more about this cooking method, called leaching.
More ways to lower potassium:
- Drain the liquid from canned fruits and vegetables
- Avoid the juices from cooked meats
- If you love orange juice, try eating an orange instead—the potassium in orange juice is much more concentrated
4. Consider a plant-forward diet
There is some evidence that choosing plant-based foods more often than meat may help slow the progression of CKD.
You don’t need to become a vegetarian. Just consider choosing meatless meals more often than you might be doing now. You might make meatless Mondays a family routine.
Choose meatless proteins carefully, though, because some plant-based meat substitutes may be high in sodium.
Get expert care for kidney health
A diet for kidney health is just one part of comprehensive renal care. At Temple Health, our Nephrology team is here to help patients at every stage of kidney disease.
Call 800-TEMPLE-MED (800-836-7536) or request an appointment online.
You can also visit the National Kidney Foundation for more information.
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