Potassium is an important mineral to the body and plays roles at both the cellular and electrical level. Potassium is the principal positively charged ion (cation) in the fluid inside of cells, while sodium is the principal cation in the fluid outside of cells. Potassium concentrations are about 30 times higher inside than outside cells, while sodium concentrations are more than ten times lower inside than outside cells. Together with sodium, they maintain the cell membrane potential (to read more on this read the article on sodium).
Because of the control of membrane potential is very important for muscular contraction of the soft tissue and regulation of heart rhythm.
There are a limited number of enzymes that require the use of potassium for production and activity, according to the Linus Pauling Institute at Oregon State University. For instance, the use of adenosine triphosphate (ADT) in the production of energy requires the presence of both sodium and potassium.
Potassium deficiency (hypokalemia)
The symptoms of hypokalemia are related to alterations in membrane potential and cellular metabolism. They include fatigue, muscle weakness and cramps, and intestinal paralysis, which may lead to bloating, constipation, and abdominal pain. Severe hypokalemia may result in muscular paralysis or abnormal heart rhythms (cardiac arrhythmias) that can be fatal.
Hypokalemia is most commonly a result of excessive loss of potassium, like from prolonged vomiting, the use of some diuretics, and some forms of kidney disease.
There are some conditions that may increase the risk of hypokalemia:
- The use of potassium-wasting diuretics (thiazide diuretics or furosemide)
- Severe vomiting or diarrhea
- Overuse or abuse of laxatives
- Anorexia nervosa or bulimia
- Magnesium depletion
- Congestive heart failure
Food and Nutrition Board of the Institute of Medicine established an adequate intake level (AI) for potassium based on intake levels that have been found to lower blood pressure, reduce salt sensitivity, and minimize the risk of kidney stones.
|Adults||19 years and older||4,700||4,700|
The richest sources of potassium are fruit and vegetables.
The next table shows some food sources of potassium and how much potassium they hold.
|Potato, baked with skin||1 medium||926|
|Prune juice||6 fluid ounces||528|
|Plums, dried (prunes)||½ cup||637|
|Orange juice||6 fluid ounces||372|
|Tomato juice||6 fluid ounces||417|
|Raisin bran cereal||1 cup||362|
|Artichoke, cooked||1 medium||343|
|Lima beans, cooked||½ cup||485|
|Acorn squash, cooked||½ cup (cubes)||448|
|Spinach, cooked||½ cup||420|
|Sunflower seeds||1 ounce||241|
The epidemiological data suggest that a modest increase in fruit and vegetable intake (rich sources of dietary potassium), especially in those with hypertension and/or relatively low potassium intakes, could significantly reduce the risk of stroke.
Increasing potassium intake by consuming a diet rich in fruit and vegetables may help lower blood pressure and may have other health benefits. Supplemental potassium might help lower blood pressure in some individuals, but potassium supplements should only be used in consultation with a medical provider.
Multivitamin supplements contain potassium but doses higher than 99 mg are prescribed to prevent and treat potassium depletion and hypokalemia. Intake of very high doses of potassium, as a part of a treatment of hypokalemia, must be prescribed by a doctor which will monitor serum potassium levels. Because of possible serious side effects, before taking potassium supplements consult your healthcare provider.
Hyperkalemia occurs when potassium intake exceeds the capacity of the kidneys to eliminate it.
Conditions that increase the risk of hyperkalemia are:
- acute or chronic renal (kidney) failure,
- the use of potassium-sparing diuretics,
- insufficient aldosterone secretion (hypoaldosteronism).
Gastrointestinal symptoms are the most common side effects of potassium supplements, including nausea, vomiting, abdominal discomfort, and diarrhea. Taking potassium with meals or taking a microencapsulated form of potassium may reduce gastrointestinal side effects. The most serious adverse reaction to potassium supplementation is hyperkalemia.
Linus Pauling Institute recommends increasing potassium intake to at least 4.7 grams/day by increasing consumption of potassium-rich foods, especially fruit, vegetables, and nuts.