Potassium is essential for heart health, muscles and bones, glucose metabolism, and more. Both excess and insufficient levels can be detrimental, so it’s important to get the right amount. Read more about the health benefits, food sources, optimal intake, and side effects of potassium.
What is Potassium?
Potassium is an essential mineral vital for the proper functioning of all living cells.
It is one of the most abundant positively charged ions (cation) in the human body, present in high concentrations in muscles, bone, liver and red blood cells [1, 2].
Concentration difference between potassium inside and outside of a cell is maintained by Na-K-ATPase enzyme that actively pumps potassium into the cell while moving sodium out of the cell [3, 2].
Western diets with more processed foods and fewer fruits and vegetables are lower in potassium and higher in sodium. Healthier diets consumed by our ancestors are richer in potassium .
Therefore, diets higher in potassium is associated with many positive health outcomes. However, this association may be because diets higher in potassium are generally healthier.
- Protects the heart
- Lowers blood pressure
- Improves glucose metabolism
- Supports the kidneys
- May strengthen the bones
- Interacts with certain medications
- May not suitable in chronic kidney disease
- Excess levels can be toxic
Roles & Functions
The major functions of potassium are the maintenance of the cell’s membrane potential and regulation of the fluid within the cell .
Potassium is important for [5, 6]:
- muscle contraction
- nerve impulse transmission
- normal heart functioning
- prevention of excessive fluid retention
- maintenance of proper pH within the body
- normal growth and muscle building
Potassium is required for the production of carbohydrates, proteins, and energy in the form of adenosine triphosphate (ATP) .
A large number of enzymes that participate in several major metabolic processes require the presence of potassium to function properly .
Antioxidant and Anti-inflammatory Effects
An increase in potassium concentration blocks dangerous oxygen species formation by blood vessel cells or white blood cells.
Dietary potassium may protect against cardiovascular damage through its antioxidant effects. It has a blocking effect on interleukin IL-17A production in T lymphocytes [9, 10].
Health Benefits of Potassium
Note: The benefits of adequate potassium intake may not translate to potassium supplementation benefits in people with normal dietary status.
1) Potassium Deficiency
Low potassium blood levels (hypokalemia) can be detrimental to heart health and cause a range of unpleasant symptoms. It’s effectively treated with oral or injected potassium [11, 12].
2) High Blood Pressure
Potassium supplementation lowers arterial blood pressure in humans with hypertension (high blood pressure) [13, 14].
Previous studies have found that potassium may lower blood pressure in hypertensive patients who consume a lot of sodium [15, 16].
On the other hand, it does not or only minimally decreases blood pressure in humans with normal blood pressure .
An increase in potassium intake of at least 0.78 g per day is associated with a significant reduction in systolic blood pressure by 4.9 mm Hg and diastolic pressure by 2.7 mm Hg .
The DASH (Dietary Approaches to Stop Hypertension) diet, which is also rich in potassium, may reduce blood pressure by 5 mm Hg (systolic) and 3 mm Hg (diastolic).
This diet also decreased the risk of coronary heart disease and stroke [18, 19].
African Americans have a relatively low intake of potassium and a high prevalence of elevated blood pressure and salt sensitivity. Therefore, they would especially benefit from an increased intake of potassium .
Blood pressure-lowering effect of potassium may be related to its diuretic activity, and effects on the nervous system, blood vessels, the renin-angiotensin-aldosterone system, and natriuretic hormone.
Increasing dietary potassium intake from foods may reduce the need for antihypertensive medication in patients with essential hypertension. In a study of 54 participants, 38% of hypertensive patients on the high-potassium diet had well-controlled blood pressure without any need for drug therapy .
3) Stroke Prevention
In a study of nearly 10,000 participants, increased intake of potassium was associated with lower rates of stroke but only among black men and hypertensive men .
In two comprehensive studies of over 180,000 nurses, an increase in potassium intake (by 1g/day) slightly but significantly reduced the risk of stroke .
A 10-mmol increase in daily potassium intake was associated with a 40% reduction in stroke-associated mortality among 859 individuals over the span of 12 years .
Lower blood potassium levels were associated with an increased stroke incidence in 6,500 older adults, especially in those with atrial fibrillation (irregular heartbeat) .
4) Heart Disease
A review of clinical trials on potassium and heart health suggested “low-sodium/high-potassium diets as a critical strategy for prevention and treatment of hypertension and cardiovascular disease” .
The balance between potassium and sodium is more strongly associated with an increased risk of heart disease than either sodium or potassium intake alone .
A study of 12,267 US adults, showed that higher potassium intake was associated with a lower risk of dying from heart disease .
Low dietary potassium intake in 58,730 Japanese men and women was associated with a higher risk of dying from heart disease .
On the other hand, some studies show no association between potassium intake and the risks of coronary heart disease and cardiovascular death .
5) Insulin Resistance
Potassium is important for insulin secretion from the pancreatic cells [15, 31].
Low potassium intake or blood potassium levels are associated with an increased risk for insulin resistance and diabetes, especially in African Americans and those on thiazide diuretic treatment [15, 31, 32, 33, 34].
Potassium depletion studies show that low serum potassium decreases glucose tolerance associated with reduced insulin secretion and leads to marked alterations in glucose metabolism [35, 36].
In over 7,500 Korean adults, high potassium intake was associated with a 39% reduced risk of metabolic syndrome, which involves obesity and insulin resistance .
In a small study on African-Americans, potassium supplementation prevented the progression of prediabetes to diabetes by improving glucose metabolism .
6) Kidney Disease
Study of 13,917 participants from NHANES, suggested that higher dietary intake of potassium is associated with a lower incidence of chronic kidney disease .
Potassium supplementation can reduce kidney inflammation leading to a regression of chronic kidney disease.
Chronic potassium depletion causes kidney functional and structural changes, interstitial nephritis (inflammation of the kidney), or cyst formation in animals and humans [40, 41, 42, 43].
Studies in hypertensive rats showed that a high potassium intake prevented vascular, glomerular, and tubular damage of kidneys [44, 45].
Adequate potassium intake is essential for kidney health, but the therapeutic effects of supplementation require further research.
Large observational studies have shown that both men and women getting more potassium had lower chances of developing kidney stones [46, 47].
Increasing dietary or supplemental potassium intake has been found to decrease calcium excretion in urine. Low levels of calcium in the urine decrease the risk of developing kidney stones .
In studies of 150 patients, potassium citrate was effective in reducing the stone size and symptoms of kidney stones in both adults and children [49, 50].
No valid clinical evidence supports the use of potassium for any of the conditions in this section. Below is a summary of up-to-date animal studies, cell-based research, or low-quality clinical trials which should spark further investigation. However, you shouldn’t interpret them as supportive of any health benefit.
7) Bone and Muscle Loss
Supplementation with potassium increased the rate of bone formation and decreased bone degradation in one study of older women .
“Alkaline diets” high in potassium may favor the preservation of muscle mass in older men and women. Potassium-rich foods relieve an acidic environment in the body caused by eating the typical Western diet that is rich in meat, dairy, and processed food, and protect from loss of bone density and muscle wasting .
Further research is needed to examine the effects of potassium on bone and muscle loss.
8) Rheumatoid Arthritis Symptoms
In a trial of 32 potassium-deficient patients, nearly half of those who took 6,000 mg of potassium daily for 28 days reported a significant pain reduction. Another one-third of the participants reported a moderate decrease in pain. More studies are warranted .
Animal and Cellular Research (Lacking Evidence)
No clinical evidence supports the use of potassium for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based studies; they should guide further investigational efforts but should not be interpreted as supportive of any health benefit.
Lithium Side Effects
Animal and cell-based research suggests that potassium supplementation may protect against lithium-induced kidney damage by enhancing its elimination .
In a mouse model of Alzheimer’s disease, increased potassium intake reduced amyloid-beta peptide in brain tissues, improved cognitive performance, and decreased inflammation and oxidative stress .
Potassium Sources & Intake
Major food sources containing potassium are fruit (bananas, dried apricots, prunes, dates, avocados, cantaloupe, citruses), vegetables (dark leafy greens, potatoes, tomatoes, squash), legumes (especially beans), mushrooms, dairy, nuts, and fish [56, 7].
Potassium-containing supplements are available in the form of salts: gluconate, citrate, chloride, bicarbonate, and acetate.
They are commonly used to treat low levels of potassium in patients who do not have enough potassium in their regular diet or have lost potassium due to illness or treatment with certain medications.
Supplemental potassium should be provided under medical supervision due to potential toxicity [57, 58].
Approximately 90% of dietary potassium is absorbed in the small intestine by passive diffusion .
The potassium is primarily balanced by kidney excretion in urine. Approximately 80 – 90% is excreted in the urine, while the remainder is excreted mainly in feces, with much smaller amounts being lost in sweat .
Because it is easily excreted by the kidneys rather than stored in the body, humans need to constantly consume potassium.
Recommended adequate intake of potassium for adults is set at 4.7 g/day .
In individuals whose kidney function is impaired, a potassium intake below 4.7 g/day is appropriate because of irregular heart rhythm from the resulting elevated blood potassium concentration .
Even though the Western diet has led to a diet low in potassium, potassium deficiency rarely occurs through the inadequate intake of dietary potassium .
Presently, less than 3% of the population have total potassium intakes that exceed the adequate intake of potassium. The average intake by adults is approximately 2.2 – 3.3 g/day .
Potassium deficiency can develop as a consequence of increasing losses through the gut (prolonged vomiting or diarrhea) or kidneys (Fanconi syndrome, Cushing’s syndrome, Conn’s syndrome, treatment with diuretics, amphotericin B, cisplatin, theophylline) .
- Muscle weakness and cramps
- Abdominal pain
- Mental disturbances (depression and confusion)
Severely decreased potassium levels may lead to muscle injury, paralysis, abnormal heart rhythms and impaired respiration that can be fatal .
Potassium Side Effects & Safety
There are no reports of adverse effects associated with potassium naturally occurring in food in healthy individuals .
Abdominal discomfort has been reported with slow-release and wax matrix formulations as well as oral solutions of potassium salts, but not with potassium from the diet .
Potassium chloride irritates upper digestive tract especially in association with delayed stomach emptying. Lesions and ulcerations of the gut lining may occur in some patients [65, 66].
Supplement-drug interactions can be dangerous and, in rare cases, even life-threatening. Always consult your doctor before supplementing and let them know about all drugs and supplements you are using or considering.
In patients with impaired kidney function or those who take potassium-sparing diuretics, angiotensin receptor blockers, or angiotensin-converting enzyme inhibitors, potassium-containing supplements and salt substitutes may lead to high potassium in the blood and life-threatening abnormal heart rhythms .
In patients with chronic kidney failure, potassium supplementation must be considered carefully because kidneys are the major regulator of potassium balance [7, 68].
Patients with a previous history of ulcers and bleeding must be considered carefully for oral potassium supplementation because some potassium salts can be irritating to the gut lining [7, 68].
Serum/Blood Potassium Levels
The normal range for serum potassium is narrow: 3.5 to 5.5 mmol/L; minor departure from this range (by less than 1.0 mmol/L) is associated with major health risks .
The distribution of potassium between the intracellular and extracellular fluids can markedly affect the serum potassium level without a change in total body potassium .
Hypokalemia is defined as a serum potassium concentration of less than 3.5 mmol/L.
It may be caused by the entry of potassium into cells (regulated by insulin, acid-base status, aldosterone, and catecholamines), and a total body depletion of potassium due to kidney, gut, or sweat losses.
Although poor intake is an uncommon cause, patients with extremely poor dietary intake (alcoholics) and patients on severe weight-reduction programs are in danger of developing severe potassium deficiency [70, 2, 69, 71].
Hyperkalemia is defined as a serum potassium concentration above 5.5 mmol/L. Serum potassium above 6.5 mEq/L is associated with a significant risk of death and should be handled as an emergency.
It occurs in kidney failure, adrenal gland insufficiency, and massive tissue damage such as in trauma, marked destruction of red blood cells, and in the tumor lysis syndrome [70, 2, 69, 71].
Both hypokalemia and hyperkalemia may cause asymptomatic changes in electrocardiogram (ECG), abnormal heart rhythms, and muscle weakness .