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Potassium 

Other name(s):

KCl, potassium chloride

General description

Potassium is a mineral element. It’s found in nature as a type of salt. It comes as potassium chloride or potassium nitrate. It plays a major role in making nerve signals that are needed for skeletal smooth muscle and heart muscle contractions.

It helps keep blood pressure normal. It’s needed for keeping electrolyte and pH balance. This is the acidity of the blood and other fluids in the body.

Most potassium in our body is found in muscle and lean tissue cells. Potassium is in most foods. It’s easily absorbed by the body.

Potassium salts dissolve in water (water soluble). It’s found in solution as a positively charged particle (cation). Potassium is the major cation inside living cells.

We need potassium to keep the electrochemical balance across cell membranes. This is vital to transmit nerve signals. This leads to skeletal muscle contraction, hormone release, and smooth muscle and heart contraction.

Potassium levels are controlled in the kidneys by a hormone called aldosterone.

Medically valid uses

Foods high in potassium may help manage high blood pressure (hypertension).

A diet full of fruits, vegetables, high-potassium foods and low-fat dairy foods has been shown to lower blood pressure and calcium excretion. Potassium supplements may be advised for some health conditions. But talk with your healthcare provider before taking potassium supplements.

Unsubstantiated claims

There may be benefits that have not yet been proven through research.

Research in animals shows that potassium may prevent strokes. It may prevent kidney damage due to high blood pressure. But these effects in humans aren’t known.

Recommended intake

There is no Recommended Dietary Allowance (RDA) for potassium. The daily Adequate Intake (AI) has been set based off the average intake of healthy people. It’s given in milligrams (mg) per day.

Age Group

AI (mg/d)

Infants (0 to 6 months)

400 mg

Infants (7 to 12 months)

700 mg

Children (1 to 3 years)

3,000 mg

Children (4 to 8 years)

3 3,800 mg

Children (9 to 13 years)

4,500 mg

Adolescents and Adults (14+ years)

4,700 mg

Pregnancy

4,700 mg

Lactation

5,100 mg

Potassium comes as an oral liquid and tablet.

It’s available in many foods. This is because it’s a main part of living cells. Good sources include vegetables and fruits, such as bananas, citrus fruits, and tomatoes. They also include milk and yogurt, and fresh meats. According the National Institutes of Health, most people in the U.S don't get enough potassium. Below is the potassium content of some food sources.

Food

Potassium content

Tomato paste (1 cup)

1,221 mg

Avocado (1 medium)

1,097 mg

Potato, baked w/ skin (1 potato)

844 mg

Navy beans (1 cup, boiled)

669 mg

Prunes, dried (10 prunes)

626 mg

Dates, dried (10 dates)

541 mg

Cantaloupe, raw (1 cup pieces)

494 mg

Honeydew, raw (1 cup pieces)

461 mg

Banana, raw (1 medium)

451 mg

Milk, skim (8 fluid oz)

406 mg

Milk, whole (8 fluid oz)

370 mg

Yogurt (6 oz)

350 mg

Apricots, raw (3 medium)

313 mg

Nectarine, raw (1 medium)

288 mg

Tomato, raw (1 tomato)

273 mg

Orange, raw (1 medium)

250 mg

Strawberries, raw (1 cup)

247 mg

Pear, raw (1 medium)

208 mg

Peach, raw (1 medium)

171 mg

Potassium is lost during cooking. Adding potassium chloride to cooking water may keep it from leaking out into the water. Use a small amount of water when cooking vegetables. Be careful not to overcook vegetables. Steaming foods will help retain potassium levels.

Low potassium levels (hypokalemia) can cause muscle weakness, lethargy, and irregular heart rate (arrhythmia). Low levels make it hard for the nerves to fire signals. This gets in the way of muscle contraction. Other signs of low potassium levels include:

  • Nausea

  • Fragile bones

  • Enlarged adrenal gland (adrenal hypertrophy)

  • Decreased growth rate

  • Weight loss

  • Irrational behavior

Deficiency doesn’t occur under normal conditions. This is because it’s in many foods. But certain issues can lead to potassium deficiency. These include:

  • Vomiting and diarrhea that lasts a long time

  • Water pill (diuretic) use

  • Laxative and steroid abuse

  • Anorexia

  • Chronic starvation

  • Hormone problems

If you’re taking certain water pills, your healthcare provider may give you a potassium supplement. He or she should closely track your potassium levels.

Side effects, toxicity, and interactions

High potassium levels (hyperkalemia) are dangerous and can be deadly. Symptoms of too much potassium are similar to signs of low levels. These can include muscle weakness, heart rhythm issues, and cardiac arrest. Cells have trouble responding to nerve impulses with too much potassium. This affects muscle contractions.

High potassium levels can be caused by kidney problems or hormonal imbalances. They can also be due to excess supplement use.

Crushing injuries that cause cell damage and red blood cell hemolysis can cause more potassium to go into the bloodstream. This can cause high levels of potassium. Intense exercise can cause potassium levels to rise. But this often isn’t dangerous.

High potassium levels can cause cardiac arrest. Because of this, supplements usually aren’t advised. You shouldn’t take them unless your healthcare provider tells you to.

Women who are pregnant or breastfeeding should talk to their healthcare providers before taking any supplements.

Some water pills (diuretics) can cause low potassium levels. These medicines are used to lower high blood pressure. They are also used to treat swelling (edema). These medicines increase the amount of potassium lost in the urine. They can cause low levels of potassium. This includes the medicines:

  • Furosemide

  • Bumetanide

  • Chlorothiazide

  • Metolazone

Other types of diuretics decrease the amount of potassium that your kidneys get rid of. They can cause your potassium levels to rise. These are called potassium-sparing diuretics. You shouldn’t take potassium supplements if you take these kinds of medicines. They include amiloride and spironolactone.

Other medicines for blood pressure can cause high potassium levels. These are called angiotensin converting enzyme (ACE) inhibitors.

If you’re taking a water pill or ACE inhibitor, talk to your healthcare provider before taking any supplements.

Additional information

People may use potassium chloride as a salt replacement when trying to lower their blood pressure. Talk to your healthcare provider before you try this.

Online Medical Reviewer: Cynthia Godsey
Online Medical Reviewer: Diane Horowitz MD
Online Medical Reviewer: Rita Sather RN
Date Last Reviewed: 3/1/2019