Potassium is an important mineral for sustaining life, but there is such a thing as “too much of a good thing.” Learn the function of potassium in the body, why potassium homeostasis is key for heart health, and the different levels of potassium in food.

What Is Potassium?

Potassium is an essential electrolyte that your body, specifically your heart, nerves, and muscles, needs to work properly.

Potassium regulates a wide range of physiologic functions including muscle contraction, regular heartbeat, and the movement of nutrients into cells and waste products out of cells. A diet rich in potassium helps to offset some of sodium’s harmful effects on blood pressure.

Potassium and Heart Health

The rhythmic contractions of the heart are controlled by periodic changes of the membrane potential, called action potentials, within the cells of the heart muscle (cardiac myocytes). Potassium is both essential to generating a regular heartbeat and stabilizing the heart, helping to stave off potentially deadly cardiac arrhythmias.

Most of the potassium that you need will be consumed in your diet. Foods that are rich in potassium help manage your blood pressure by lessening the effects of sodium. Potassium does this through its ability to promote sodium excretion in urine and ease tension in your blood vessel walls.

Meeting your daily potassium requirement helps keep your heart working at its best. A healthy potassium blood level is between 3.5 and 5.0 milliequivalents per liter (mEq/L). Potassium levels that are too high or too low can cause or exacerbate heart failure.

Studies have shown that increasing potassium intake can reduce the risk of cardiovascular diseases, such as high blood pressure, heart disease, and stroke, but the mechanism responsible for this is unknown. Some researchers believe that potassium may prevent atherosclerosis, or hardening of the arteries, but more research is needed to support these claims.

Low Potassium Levels

Low potassium levels in the blood, also known as hypokalemia, can be due to a number of conditions including:

  • Medicines, such as diuretics (water pills) or certain antibiotics
  • Diarrhea or vomiting
  • Eating disorders (such as bulimia)
  • Hyperaldosteronism (over production of the male hormone aldosterone)
  • Laxative overuse, which can cause diarrhea
  • Chronic kidney disease
  • Low magnesium level
  • Excessive sweating (hyperhidrosis)
  • Genetic disorders, such as hypokalemic periodic paralysis or Bartter syndrome

Mildly low potassium levels usually cause no symptoms, but larger decreases may cause the following symptoms:

  • WeaknessFatigueConstipationMuscle twitchesMuscle cramps or weaknessMuscles paralysisAbnormal heart rhythmsKidney problems

High Potassium Levels

Having too much potassium in the blood, a condition called hyperkalemia, can be dangerous to your heart health. The kidneys are responsible for maintaining the balance of potassium in the blood. The following condition may put you at risk of hyperkalemia:

  • Chronic kidney disease
  • Diabetes
  • Congestive heart failure
  • Medications that disrupt potassium balance, such as certain blood pressure-lowering drugs
  • Major burns or trauma to the body
  • Chronic alcoholism

At first, you may not notice any symptoms, but hyperkalemia may cause symptoms of:

  • Abdominal (belly) pain and diarrhea
  • Chest pain
  • Heart palpitations or arrhythmia (irregular, fast or fluttering heartbeat)
  • Muscle weakness or numbness in limbs
  • Nausea and vomiting

Dietary Sources of Potassium

Potassium is an essential nutrient that is naturally present in many foods and is present in all body tissues. Potassium levels are tightly regulated because it is required for normal cell function. This mineral helps to maintain the balance between intracellular fluid volume and transmembrane electrochemical gradients. 

When to Seek Medical Attention

Severe hyperkalemia can lead to heart stoppage and death. At first, you may not notice any symptoms, but hyperkalemia may cause symptoms of:

  • Abdominal (belly) pain and diarrhea
  • Chest pain
  • Heart palpitations or arrhythmia (irregular, fast, or fluttering heartbeat)
  • Muscle weakness or numbness in limbs
  • Nausea and vomiting

If you experience any of these symptoms, call an ambulance or head to the emergency room immediately.

Although potassium supplements are available, most people can get the potassium they need from the food they eat and the fluids they drink. Potassium-rich foods include:

  • Apricots and apricot juiceAsparagusAvocadosBrown riceCantaloupe and honeydew melonCoffee and teaFat-free or low-fat (1%) milkFat-free yogurtMost fishMilkGrapefruit and grapefruit juice (talk to your healthcare provider if you’re taking a cholesterol-lowering drug)Leafy greens like spinach and kaleHalibutLima beansMushroomsOranges and orange juicePeasPotatoes (white and sweet potatoes)Prunes and prune juiceRaisins and datesTomatoes, tomato juice, and tomato sauceTuna

Planning a Low Potassium Diet

High potassium levels in the blood can cause serious heart troubles, especially if you are at high risk of heart failure, but before you severely restrict the potassium in your diet you may want to check in with a healthcare professional to talk about the risks of high potassium and how a low-potassium diet can help.

Talk to Your Healthcare Provider

If you are at high risk for hyper- or hypo- kalemia or experience any of the aforementioned symptoms, seek immediate medical attention. Dietary changes can help prevent and treat high or low potassium levels.

Talk to a healthcare professional to understand any risk you might have for hypo- or hyper- kalemia, as they may recommend foods that you may need to limit, avoid, or increase depending on your potassium status.

Summary

Potassium is good in the heart and is found abundantly in the foods we eat and fluids we drink but too much can cause serious heart problems, especially in those with diabetes, hypertension, or kidney disease, who are at high risk of heart failure. Before starting a low potassium, diet check in with a healthcare professional to safely plan your course.

A Word From Verywell 

The body does a great job of tightly regulating potassium levels, and most of the time you won’t feel symptoms if your levels are slightly high or low. Even more, most U.S. adults get a healthy amount of potassium in their diet through milk, coffee, tea, other nonalcoholic beverages, bananas, avocados, and potatoes and do not have to make changes in their diets or use potassium supplements to meet their daily requirements.

If you have a condition that weakens your heart, that may not be the case. You may need to pay close attention to the amount of potassium you ingest. But before making any drastic changes to your diet, consult a healthcare professional who will help you adjust your diet in the safest way possible.

Frequently Asked Questions

  • How does potassium affect your heart rate?
  • High potassium levels in the blood can trigger an irregular heartbeat that is sometimes accompanied by a racing heart and chest discomfort. If left untreated severe hyperkalemia can lead to heart stoppage and death.
  • Can drinking a lot of water help to lower potassium?
  • It’s always a good idea to stay hydrated, especially with water, given that it is essential to maintaining electrolyte balance, but drinking an excessive amount can lead to a potentially life-threatening loss of potassium in the urine, sometimes called water intoxication.
  • Are there ways to flush excess potassium from your body?
  • Water pills, also known as diuretics, are commonly used to help rid the body of extra potassium. They work by making your kidney create more urine which flushes out potassium in the process. The drug Kayexalate (sodium polystyrene sulfonate) may also be used to treat high potassium as it removes potassium through your intestines before it is absorbed in the body.

High potassium levels in the blood can trigger an irregular heartbeat that is sometimes accompanied by a racing heart and chest discomfort. If left untreated severe hyperkalemia can lead to heart stoppage and death. 

It’s always a good idea to stay hydrated, especially with water, given that it is essential to maintaining electrolyte balance, but drinking an excessive amount can lead to a potentially life-threatening loss of potassium in the urine, sometimes called water intoxication.

Water pills, also known as diuretics, are commonly used to help rid the body of extra potassium. They work by making your kidney create more urine which flushes out potassium in the process. The drug Kayexalate (sodium polystyrene sulfonate) may also be used to treat high potassium as it removes potassium through your intestines before it is absorbed in the body.