Potassium
Potassium
Other name(s):
KCl, potassium chloride
General description
Potassium is a reactive, metallic element. It’s found in nature as a "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 normal blood pressure. It’s also needed for keeping electrolyte and pH balance (the acidity of the blood and other bodily fluids).
Most potassium in our body is found in muscle and lean tissue cells. Potassium is in most foods. It’s readily absorbed by the body.
Potassium salts are 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 crucial in conducting 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
Potassium reduces high blood pressure (hypertension).
A diet rich in fruits, vegetables, and high-potassium, low-fat dairy products has been shown to decrease blood pressure and decrease calcium excretion. But potassium supplements aren’t usually recommended. This is because they can cause side effects, such as cardia arrest.
Unsubstantiated claims
Please note that this section reports on claims that have not yet been substantiated through studies.
Research in animals shows that potassium may prevent strokes. It may also prevent kidney damage due to high blood pressure. However, 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 grams per day.
Age Group |
AI (g/d) |
Infants (0 to 6 months) |
0.4 |
Infants (7 to 12 months) |
0.7 |
Children (1 to 3 years) |
3.0 |
Children (4 to 8 years) |
3.8 |
Children (9 to 13 years) |
4.5 |
Adolescents and Adults (14+ years) |
4.7 |
Pregnancy |
4.7 |
Lactation |
5.1 |
Potassium comes as an oral liquid and tablet.
It’s widely available in foods. This is because it’s a main component 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. The following table lists 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 leaching out into the water. Use a small amount of water when cooking vegetables. Be careful not to overcook vegetables. Steaming foods will also help retain potassium levels.
Low potassium levels (hypokalemia) can cause muscle weakness, lethargy, and irregular heart rate (arrhythmia). Low levels make it tricky for the nerves to fire signals. This gets in the way of muscle contraction. Other signs of low potassium levels include nausea, bone fragility, and enlarged adrenal gland (adrenal hypertrophy). They also include decreased growth rate, weight loss, and 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 the following:
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. If you’re taking more than 300 mg per day, your healthcare provider will watch you closely. High potassium leads to decreased calcium excretion. This is often a good thing.
Side effects, toxicity, and interactions
High potassium levels (hyperkalemia) are dangerous. 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 cause by kidney problems or hormonal imbalances. They can also be due to excessive 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 also cause potassium levels to rise. But this often isn’t dangerous.
Since high potassium levels can cause cardiac arrest, supplements usually aren’t recommended. 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 can cause low potassium levels. You shouldn’t take potassium-sparing diuretics are available with potassium supplements. If you’re taking a water pill, 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. It has a bitter taste. This reduces the risk of high potassium levels because the taste limits how much people use. Talk to your healthcare provider, though, before you try this. Low potassium levels may play a bigger role in high blood pressure than high levels of sodium.
Updated:  
March 21, 2017
Sources:  
Treatment and prevention of hyperkalemia in adults. UpToDate.
Reviewed By:  
Poulson, Brittany, RD, CDE,Wilkins, Joanna, R.D., C.D.