How to effectively lower potassium levels with medication and low-potassium foods like blueberries and tuna

Lindsay Kalter
·5 min read
Blueberries in Hands
Blueberries are a low-potassium fruit and great alternative to other high-potassium fruits like bananas. andrew welch / Unsplash
  • Too much potassium can lead to potentially harmful conditions such as hyperkalemia, which may occur in people whose kidneys don't sufficiently filter potassium.

  • Hyperkalemia is frequently managed with a simple change in diet, such as avoiding potassium-rich foods including bananas, avocados, and sweet potatoes, to keep potassium at a healthy level.

  • Diuretics and potassium binders may also be prescribed to manage hyperkalemia but should be used with caution and only under medical supervision.

  • This article was medically reviewed by Samantha Cassetty, MS, RD, nutrition and wellness expert with a private practice based in New York City.

  • Visit Insider's Health Reference library for more advice.

A healthy amount of potassium helps regulate your heartbeat, lowers blood pressure, and keeps muscles and nerves functioning at optimal levels. Although many adults in the US don't get enough potassium in their diet, some may have medical conditions that make it dangerous to get too much. 

Too much potassium can lead to potentially harmful changes in heart rhythm and should be carefully monitored and managed, says Linda Antinoro, a registered dietician at Brigham and Women's Hospital in Boston.

Before pursuing treatment, a doctor will first make sure current medications, such as ACE inhibitors or blood pressure medicine, are not the source of your potassium-related problems. 

Here's what you need to know about potassium levels, related medical complications, and the safest options for decreasing your intake, if necessary. 

What is hyperkalemia? 

Hyperkalemia is a condition that occurs when too much potassium is in the blood. Because kidneys are responsible for filtering potassium from the body, Antinoro says other medical conditions that compromise kidney function may lead to hyperkalemia. These include:

  • Addison's disease

  • Chronic kidney disease

  • Unmanaged diabetes

Hyperkalemia may occur in people whose kidneys do not sufficiently filter potassium from the body or if certain medications interfere with that process, Antinoro says. For example, chronic kidney disease and unmanaged diabetes may both contribute to hyperkalemia.

Aldosterone, the hormone responsible for instructing the kidneys to remove potassium, could be compromised by various medical conditions, including Addison's disease.

Dangerously high potassium levels are often asymptomatic, but people who do experience symptoms may feel some of the following:

  • Fatigue

  • Muscle weakness

  • Paralysis

  • Abnormal heart rhythms

  • Nausea

Potassium levels can only be detected through blood tests, Antinoro says. 

"If the levels are greater than 5.5 [milliequivalents per liter], that will be diagnosed as hyperkalemia," Antinoro says. "You would need some medical management for that."

Avoid high-potassium foods

Once the diagnosis has been made, hyperkalemia is often managed with a simple change in diet, Antinoro says. 

The daily recommended intake for healthy individuals is 3,500 mg to 4,500 mg of potassium, so someone with hyperkalemia may be limited to 2,000 mg.

To keep potassium at a healthy level, people with this diagnosis should avoid potassium-rich foods such as: 

  • Bananas –  422 mg of potassium

  • Avocados – 728 mg for one cup

  • Sweet potatoes – 542 mg for a medium-sized potato 

  • Spinach – about 800 mg for one cup cooked or canned

  • White beans – 1,190 mg for one cup

"First, cut out the bananas and avocados and leafy greens," Antinoro says. And good news, potassium isn't in every healthy whole food out there. You can still eat healthily with low-potassium foods like:  

  • Blueberries - 1 cup contains 114 mg of potassium

  • Pear - 1 medium pear contains about 206 mg 

  • String green beans - 1 cup, raw, contains about 211 mg 

  • Whole wheat pasta - 1 cup, cooked, contains 89.3 mg

  • Canned tuna (in water) - 1 can contains 299 mg

If, after changing your diet, potassium levels remain dangerously high, Antinoro says you should consult your doctor as you may need medical management to get your levels back on track.

Use of diuretics 

Diuretics – often used by people with excessive water retention, high blood pressure, kidney disease, or heart failure – can also help to lower potassium levels, Antinoro says.

Diuretics work by helping the kidneys expel more sodium into the urine, which can also result in less potassium retention.

According to a 2016 study, diuretics were associated with a 40% decrease in risk for hyperkalemia. However, these benefits were only seen with a class of diuretics that aren't intended to spare potassium.

Certain diuretics are considered potassium-sparing diuretics, which means you retain potassium instead of expelling it. In that case, potassium-sparing diuretics would worsen the situation.

Diuretics are not for everyone, Antinoro says. They can be useful but should be prescribed with caution and taken under medical supervision. Diuretics can interact poorly with other medications, including certain antidepressants, and they can be dangerous for people who suffer from chronic dehydration and severe kidney disease. 

Antinoro says it is crucial to talk with your doctor before taking diuretics.

Use of potassium binders 

If diuretics are not a safe option, doctors may prescribe potassium binders. These are medications that bind to excess potassium in the gut and are then expelled through the stool. For some, binders can cause uncomfortable side effects, including diarrhea, nausea, gas, and abdominal pain. 

 One drawback to potassium binders is the lack of comprehensive research on safety and effectiveness. The first potassium binder was approved by the FDA in 1958, and it wasn't until 2015 that a second one came on the market, according to a 2020 medical paper, which also recommends that binders never be the sole medication used in a hyperkalemic emergency.

Takeaways

High potassium levels may lead to a potentially dangerous condition called hyperkalemia, but there are several avenues for intervention and treatment. 

Potassium levels can often be treated and controlled through your diet. Diuretics and potassium binders should be taken with caution and only under medical supervision.

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