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Other common name(s): none (Note that there are several brand names for prescription forms of this supplement)

Scientific/medical name(s): K, K+, potassium chloride (KCl), potassium citrate, potassium acetate, potassium bicarbonate, potassium gluconate, potassium bicarbonate


Potassium is an essential mineral found in most foods. Along with sodium and calcium, potassium helps regulate major body functions, including normal heart rhythm, blood pressure, water balance in the body, digestion, nerve impulses, muscle contractions, and pH balance (the balance of acidity and alkalinity in the body). The body cannot make potassium on its own and must get it from foods. Potassium is found in foods such as apricots, potatoes, bananas, oranges, pineapples, green leafy vegetables, whole grains, beans, nuts, and lean meat. Most salt substitutes also contain large amounts of potassium. Potassium supplements may be prescribed by doctors for patients with imbalances in blood chemicals.


Potassium is a mineral that is required for the body to work normally. Most people get all the potassium they need from what they eat and drink. Available scientific evidence does not support claims that potassium supplements can prevent or treat cancer in humans. Excess potassium in the body can be toxic.

How is it promoted for use?

Some alternative medical practitioners maintain that low levels of potassium in the body may be linked to cancer, heart disease, high blood pressure, osteoporosis, depression, and schizophrenia. Some proponents claim that a diet high in sodium and low in potassium promotes tumor growth by changing the normal pH and water balance in human cells.

What does it involve?

Most foods contain potassium, so people usually get plenty of potassium from what they eat and drink. Normally, the kidneys control the level of potassium in the blood and get rid of excess in the urine. The Food and Nutrition Board of the National Academies of Sciences has set Adequate Intake of potassium at 4.7 grams per day for most adults. No upper limit was set for potassium intake from foods. Still, those with kidney disease, Addison's disease, or those taking certain blood pressure medicines may need to consume less than the Adequate Intake of potassium.

Potassium supplements are needed only by those who have low levels of potassium in their blood, a condition known as hypokalemia. The causes of hypokalemia can include diarrhea and vomiting, diabetes, certain kidney diseases, excessive sweating, overuse of laxatives, and some types of diuretics. (Diuretics are drugs that remove water from the body through urine, or "water pills"). Use of potassium supplements can be dangerous unless carefully watched by health care providers. This may mean frequent blood tests to check potassium levels.

What is the history behind it?

In the 1930s, Max Gerson began developing a controversial dietary treatment for cancer known as the Gerson Diet Therapy (see Gerson Therapy). The cornerstone of his diet was the use of potassium supplements and low sodium intake. He claimed the diet could restore proper balance of salt and water within human cells and help stop tumor growth. However, this theory has not been supported by clinical or experimental data published in respected peer-reviewed journals.

What is the evidence?

Some animal and human studies have suggested that eating foods high in potassium and low in sodium might help prevent high blood pressure, or hypertension. Dietary Approaches to Stop Hypertension, also called the DASH diet, was designed to help control blood pressure. The DASH diet can reduce blood pressure and risk of heart disease. It mainly works through weight loss, reduced salt intake, moderation in drinking alcohol (for those who drink), and eating foods that are rich in potassium. These measures are especially helpful in older people and in African Americans, although the exact reasons are uncertain. For people who already have high blood pressure, these measures can be used along with medicines to gain better control over blood pressure. This can help reduce risk of stroke and heart attack.

Some studies that observe large groups of people have found that in a number of countries where there are high-potassium diets, cancer rates are lower. In areas where there are low-potassium diets, these studies showed the cancer rates are higher. These types of studies, however, do not prove a direct connection, because there are many other factors involved. A few of these studies of individual potassium intake (rather than national averages) have found links with cancer risk. However, the main sources of potassium in foods are fruits and vegetables. This may mean that people with a diet high in potassium are at lower risk for cancer because of other compounds in these foods. Since fruits and vegetables also contain vitamins, phytochemicals, and other antioxidants, it may be that compounds besides potassium account for their helpful effects. When researchers look at large groups with different lifestyles and habits, it is also possible that their findings can be explained by other factors that were not examined.

Choosing foods from a variety of fruits, vegetables, and other plant sources such as nuts, seeds, whole grains, and beans is likely to be healthier than eating large amounts of one type of food. The American Cancer Society's most recent nutrition guidelines recommend eating a balanced diet with an emphasis on plant sources, which includes:

  • Five or more servings of vegetables and fruit each day
  • Choosing whole grains over processed and refined grains
  • Limiting processed meats and red meats
  • Balancing calorie intake with physical activity to get to or stay at a healthy weight
  • Limiting alcohol intake

One researcher has suggested a link between low potassium and high sodium levels in cells and an increased risk of cancer. But available scientific evidence does not support the idea that changes in dietary potassium intake have any impact on potassium concentrations inside cancer cells.

Are there any possible problems or complications?

This product is sold as a dietary supplement in the United States. Unlike companies that produce drugs (which must be tested before being sold), the companies that make supplements are not required to prove to the Food and Drug Administration that their supplements are safe or effective, as long as they don't claim the supplements can prevent, treat, or cure any specific disease.
Some such products may not contain the amount of the herb or substance that is on the label, and some may include other substances (contaminants). Actual amounts per dose may vary between brands or even between different batches of the same brand. In 2007, the FDA wrote new rules to improve the quality of manufacturing for dietary supplements and the proper listing of supplement ingredients. But these rules do not address the safety of the ingredients or their effects on health.
Most such supplements have not been tested to find out if they interact with medicines, foods, or other herbs and supplements. Even though some reports of interactions and harmful effects may be published, full studies of interactions and effects are not often available. Because of these limitations, any information on ill effects and interactions below should be considered incomplete.

Too much potassium supplement or salt substitute can cause potassium to build up in the blood, resulting in a condition known as hyperkalemia. The symptoms of hyperkalemia include muscle weakness, numbness and tingling, abnormal heart rhythm, muscle paralysis, trouble breathing, and even heart failure and death. Severe kidney failure and Addison's disease (a hormone deficiency) may also cause hyperkalemia. But even people with normal kidneys can overdose on potassium if they take too many supplements at once.

People who are taking potassium-sparing diuretics (such as triamterene, amiloride, and spironolactone) can build up dangerously high potassium levels if they use potassium supplements or salt substitutes. The blood pressure medicines known as ACE inhibitors (such as lisinopril, enalapril, and captopril) can cause the same problem. Those with kidney failure, diabetes, or Addison's disease should only take potassium supplements under the careful supervision of a doctor.

Other side effects of potassium supplements may include stomach or intestinal irritation, nausea, vomiting, abdominal pain, gas, and diarrhea. Talk with your doctor or pharmacist if you are thinking about potassium supplements. Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.

Additional resources

More information from your American Cancer Society

The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-227-2345).

Dietary Supplements: What Is Safe?

Complementary and Alternative Methods and Cancer

Placebo Effect

Learning About New Ways to Treat Cancer

Learning About New Ways to Prevent Cancer

The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management


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Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.

Last Medical Review: 10/21/2010
Last Revised: 10/21/2010