What is potassium?
Potassium, an element essential for maintaining normal cellular function in the body, regulates electrolyte balance, blood pressure, and electrical impulses in nerves and muscle cells.[5][6] The latter is crucial for maintaining contractile function in muscles, including the heart.
Potassium is obtained in the diet and is found in many foods, including fruits, vegetables, legumes, meat, and animal products (milk, yogurt, etc.).[1][3] In the USA, the adequate intake (AI) for potassium — the amount assumed to ensure nutritional adequacy — in adults without known health conditions is 3,400 mg/day in males and 2,600 mg/day in females, but the AI changes with age and during pregnancy (see the Dosage Information section).[1][3]
The potassium concentration in the blood is tightly regulated within a range of 3.5 to 4.5 millimoles per liter of blood (mmol/L).[5][7][6] Several factors can push blood potassium concentrations outside this range. These include dietary potassium intake, some drugs (e.g., insulin, diuretics, and potassium binders), and certain clinical conditions (e.g., chronic kidney disease and diabetic ketoacidosis).[5][7][6][8][9] Blood potassium concentrations outside the healthy reference range — hyperkalemia (high blood potassium[10]) and hypokalemia (low blood potassium[11]) — are problematic because they’re associated with an increased risk of heart problems (e.g., heart arrhythmias) or dying from a cardiovascular event.[12][13][14][15][16][17]
What are potassium’s main benefits?
Some studies have shown that short-term daily supplementation with a potassium salt (e.g., potassium chloride or potassium citrate) can lower blood pressure in adults without known health conditions[18] and in people with hypertension.[19][20] While early systematic reviews and meta-analyses found that the evidence was mixed and that there was large variability in effects between studies,[21] it now appears that supplementation with a potassium salt can cause a moderate and meaningful effect to lower blood pressure.[22][23] However, the blood-pressure-lowering effect of potassium is likely to be greatest in people with lower potassium intake at baseline, higher sodium intake at baseline, or in people who don’t use a blood-pressure-lowering medication.[23][24]
Observational studies find a correlation between higher levels of daily dietary potassium intake and a reduced risk of stroke and cardiovascular disease.[25][26] [27][28] However, because these studies estimate dietary potassium intake from food recall questionnaires, the direct protective effect of dietary potassium on cerebrovascular or cardiovascular risk cannot currently be proven.
Observational studies also show an association between higher levels of daily dietary potassium intake and better bone health.[29][30] Furthermore, randomized controlled trials show that supplementation with potassium improves aspects of bone metabolism in postmenopausal women with osteopenia[31][32] and in older adults with osteoporosis.[33][34] However, it is currently unclear whether supplementation with potassium prevents bone loss in such people.
Potassium-containing drugs — e.g., potassium chloride, potassium gluconate, potassium bicarbonate, potassium acetate, etc. — are used to treat low blood potassium (hypokalemia). Other potassium-containing drugs are also used clinically. For example, potassium citrate is used to treat some kidney defects, and potassium phosphate is used in the treatment and prevention of low blood phosphorus (hypophosphatemia).
What are potassium’s main drawbacks?
A high blood potassium concentration — hyperkalemia[10] — is associated with an increased risk of heart problems (e.g., heart arrhythmias).[14][15][16][17] Hyperkalemia-related symptoms have been associated with salt substitutes in several case studies,[35][36][37][38][39] but case studies of individual people only show what is possible rather than what is typical.
In people without known health conditions, serum potassium concentrations are between 3.5 and 4.5 millimoles per liter of blood (mmol/L).[5][7][6] A meta-analysis of randomized controlled trials found that daily supplementation with potassium chloride in the range of 22 to 140 mmol/day — equivalent to approximately 0.9 to 5.5 grams/day of potassium — caused a statistically significant but clinically meaningless increase (+0.14 mmol/L) in serum potassium.[4] Therefore, generally, supplementation with potassium is unlikely to cause hyperkalemia. Furthermore, in potassium supplementation studies, adverse effects are uncommon and biomarkers of renal function (urinary and serum sodium and creatinine) are typically unaffected.[4]
While supplementation with potassium salts (e.g. potassium chloride) can improve (i.e., lower) blood pressure,[18][19][20][22][23] some evidence shows that very high doses might increase blood pressure.[24] Consequently, if you use a potassium salt to treat high blood pressure, always use the dose recommended by your doctor.
How does potassium work?
The potassium concentration in the blood is primarily regulated by the kidneys, where potassium channels (protein structures that pass potassium ions across cell membranes) in the cells of the distal tubules regulate potassium excretion in the urine.[40][5][6] Distribution of potassium within the body’s tissues is regulated by insulin, catecholamines (e.g., noradrenaline and adrenaline), and aldosterone.[5][6]
There is a steep gradient between the potassium concentration in the blood (i.e., the extracellular potassium concentration: 3.5 to 4.5 millimoles per liter, or mmol/L) and the potassium concentration in the cells (the intracellular concentration: 120 to 140 mmol/L). This gradient is critical for maintaining normal function in every cell in the body because it helps potassium ions constantly cross the cell membrane that separates the blood from the cell, generating a membrane potential. This vitally important membrane potential drives electrical impulses in neurons and contractions in muscle cells.[5][6]
This gradient is maintained by the potassium channels found in cell membranes. One of the most important is the sodium-potassium ATPase pump, which is found in every cell in the body and uses energy — adenosine triphosphate (ATP) — to maintain the potassium (and sodium) gradient across the cell membrane.[5][6]
The correlation between higher daily dietary potassium intake and a reduced risk of stroke and cardiovascular disease[25][26] [27][28] is likely explained by the blood-pressure-lowering effect of potassium.[22][23] While some evidence shows that potassium intake causes natriuresis — increased sodium excretion in the urine — and reduces vascular resistance,[6][22][41] it is not precisely understood how supplementation with potassium lowers blood pressure.
What are other names for Potassium
- Kalium
- K+
Dosage information
The adequate intake (AI) for potassium in people without known health conditions — i.e., the daily amount assumed to ensure nutritional adequacy — is as follows:[1]
Age | Male | Female | Pregnant | Lactating |
---|---|---|---|---|
Birth to 6 months | 400 mg/day | 400 mg/day | - | - |
Infants 7–12 months | 860 mg/day | 860 mg/day | - | - |
Children 1–3 years | 2000 mg/day | 2000 mg/day | - | - |
Children 4–8 years | 2300 mg/day | 2300 mg/day | - | - |
Children 9–13 years | 2500 mg/day | 2300 mg/day | - | - |
Teens 14–18 years | 3000 mg/day | 2300 mg/day | 2600 mg/day | 2500 mg/day |
Adult 19–50 years | 3400 mg/day | 2600 mg/day | 2900 mg/day | 2800 mg/day |
Adult 51+ years | 3400 mg/day | 2600 mg/day | - | - |
Some evidence suggests that dietary potassium insufficiency might be common: the global mean potassium intake has been estimated at 2250 mg/day, with only 35% of adults estimated to be achieving adequate intakes.[2]
Potassium is found in many foods, including fruits, vegetables, legumes, meat, and animal products.[1][3] Consult the FoodData Central database to check the amount of potassium in the foods you eat.
Potassium supplements are generally safe for consumption and are unlikely to cause adverse effects if used within the recommended dosage.[4]
Frequently asked questions
Potassium, an element essential for maintaining normal cellular function in the body, regulates electrolyte balance, blood pressure, and electrical impulses in nerves and muscle cells.[5][6] The latter is crucial for maintaining contractile function in muscles, including the heart.
Potassium is obtained in the diet and is found in many foods, including fruits, vegetables, legumes, meat, and animal products (milk, yogurt, etc.).[1][3] In the USA, the adequate intake (AI) for potassium — the amount assumed to ensure nutritional adequacy — in adults without known health conditions is 3,400 mg/day in males and 2,600 mg/day in females, but the AI changes with age and during pregnancy (see the Dosage Information section).[1][3]
The potassium concentration in the blood is tightly regulated within a range of 3.5 to 4.5 millimoles per liter of blood (mmol/L).[5][7][6] Several factors can push blood potassium concentrations outside this range. These include dietary potassium intake, some drugs (e.g., insulin, diuretics, and potassium binders), and certain clinical conditions (e.g., chronic kidney disease and diabetic ketoacidosis).[5][7][6][8][9] Blood potassium concentrations outside the healthy reference range — hyperkalemia (high blood potassium[10]) and hypokalemia (low blood potassium[11]) — are problematic because they’re associated with an increased risk of heart problems (e.g., heart arrhythmias) or dying from a cardiovascular event.[12][13][14][15][16][17]
Potassium deficiency can lead to hypokalemia — low blood potassium, less than 3.5 millimoles per liter of blood (mmol/L) — which can cause a variety of signs and symptoms, including tiredness, loss of focus, loss of appetite, vomiting, and muscle weakness.[5][48][49] In more serious cases, hypokalemia can also lead to heart arrhythmias, including atrial fibrillation),[48][49][11][13][12] and is associated with an increased risk of cardiovascular-related mortality.[14][15][17]
Some studies have shown that short-term daily supplementation with a potassium salt (e.g., potassium chloride or potassium citrate) can lower blood pressure in adults without known health conditions[18] and in people with hypertension.[19][20] While early systematic reviews and meta-analyses found that the evidence was mixed and that there was large variability in effects between studies,[21] it now appears that supplementation with a potassium salt can cause a moderate and meaningful effect to lower blood pressure.[22][23] However, the blood-pressure-lowering effect of potassium is likely to be greatest in people with lower potassium intake at baseline, higher sodium intake at baseline, or in people who don’t use a blood-pressure-lowering medication.[23][24]
Observational studies find a correlation between higher levels of daily dietary potassium intake and a reduced risk of stroke and cardiovascular disease.[25][26] [27][28] However, because these studies estimate dietary potassium intake from food recall questionnaires, the direct protective effect of dietary potassium on cerebrovascular or cardiovascular risk cannot currently be proven.
Observational studies also show an association between higher levels of daily dietary potassium intake and better bone health.[29][30] Furthermore, randomized controlled trials show that supplementation with potassium improves aspects of bone metabolism in postmenopausal women with osteopenia[31][32] and in older adults with osteoporosis.[33][34] However, it is currently unclear whether supplementation with potassium prevents bone loss in such people.
Potassium-containing drugs — e.g., potassium chloride, potassium gluconate, potassium bicarbonate, potassium acetate, etc. — are used to treat low blood potassium (hypokalemia). Other potassium-containing drugs are also used clinically. For example, potassium citrate is used to treat some kidney defects, and potassium phosphate is used in the treatment and prevention of low blood phosphorus (hypophosphatemia).
A reduced-sodium added-potassium salt substitute is sometimes used to supplement a sodium-restricted (reduced salt) diet to help treat hypertension. Such salt substitutes typically contain a reduced amount of sodium chloride and an added amount of potassium chloride, and randomized controlled trials show that they can effectively reduce blood pressure.[42][43][44][45][46] However, this does not mean that more is better — some evidence shows that supplementation with potassium salts in high doses might increase blood pressure.[24]
Because high blood pressure increases the risk of cardiovascular disease and stroke-related mortality, it is possible that the blood-pressure-lowering effect of a reduced-sodium added-potassium salt substitute could reduce mortality risk. Some current evidence supports this hypothesis,[42][43][47] but due to the dearth of studies and the large between-study variability, further long-term high-quality observational studies and randomized controlled trials are needed to make firm conclusions.
A high blood potassium concentration — hyperkalemia[10] — is associated with an increased risk of heart problems (e.g., heart arrhythmias).[14][15][16][17] Hyperkalemia-related symptoms have been associated with salt substitutes in several case studies,[35][36][37][38][39] but case studies of individual people only show what is possible rather than what is typical.
In people without known health conditions, serum potassium concentrations are between 3.5 and 4.5 millimoles per liter of blood (mmol/L).[5][7][6] A meta-analysis of randomized controlled trials found that daily supplementation with potassium chloride in the range of 22 to 140 mmol/day — equivalent to approximately 0.9 to 5.5 grams/day of potassium — caused a statistically significant but clinically meaningless increase (+0.14 mmol/L) in serum potassium.[4] Therefore, generally, supplementation with potassium is unlikely to cause hyperkalemia. Furthermore, in potassium supplementation studies, adverse effects are uncommon and biomarkers of renal function (urinary and serum sodium and creatinine) are typically unaffected.[4]
While supplementation with potassium salts (e.g. potassium chloride) can improve (i.e., lower) blood pressure,[18][19][20][22][23] some evidence shows that very high doses might increase blood pressure.[24] Consequently, if you use a potassium salt to treat high blood pressure, always use the dose recommended by your doctor.
The potassium concentration in the blood is primarily regulated by the kidneys, where potassium channels (protein structures that pass potassium ions across cell membranes) in the cells of the distal tubules regulate potassium excretion in the urine.[40][5][6] Distribution of potassium within the body’s tissues is regulated by insulin, catecholamines (e.g., noradrenaline and adrenaline), and aldosterone.[5][6]
There is a steep gradient between the potassium concentration in the blood (i.e., the extracellular potassium concentration: 3.5 to 4.5 millimoles per liter, or mmol/L) and the potassium concentration in the cells (the intracellular concentration: 120 to 140 mmol/L). This gradient is critical for maintaining normal function in every cell in the body because it helps potassium ions constantly cross the cell membrane that separates the blood from the cell, generating a membrane potential. This vitally important membrane potential drives electrical impulses in neurons and contractions in muscle cells.[5][6]
This gradient is maintained by the potassium channels found in cell membranes. One of the most important is the sodium-potassium ATPase pump, which is found in every cell in the body and uses energy — adenosine triphosphate (ATP) — to maintain the potassium (and sodium) gradient across the cell membrane.[5][6]
The correlation between higher daily dietary potassium intake and a reduced risk of stroke and cardiovascular disease[25][26] [27][28] is likely explained by the blood-pressure-lowering effect of potassium.[22][23] While some evidence shows that potassium intake causes natriuresis — increased sodium excretion in the urine — and reduces vascular resistance,[6][22][41] it is not precisely understood how supplementation with potassium lowers blood pressure.
Muscle cramps are a complicated phenomenon that are associated with several factors: dehydration, glycogen depletion, overexertion, fatigue, hyperthermia, etc. For more information, see What causes muscle cramps?.
While electrolyte (potassium and sodium) depletion in the blood can trigger muscle cramps, cramps can also happen with normal levels of electrolytes. Furthermore, because blood concentrations of potassium do not typically differ between people who experience cramps during exercise and people who do not,[50] the current evidence shows that low blood potassium is unlikely to cause exercise-associated muscle cramps.
Everyone has heard that athletes eat bananas because they’re high in potassium and prevent muscle cramps; but is that true?
One ripe uncooked banana (1 serving; 115 grams) contains approximately 375 mg of potassium.[51] However, several foods contain potassium in similar or greater quantities than bananas: meat (pork, beef, and poultry), potatoes, collards, beans, watermelon.[52]
Eating bananas post-exercise may not increase the potassium in your blood in any meaningful way. One small randomized controlled trial asked 9 men to complete 60 minutes of exercise in the heat and then eat 0, 150, or 300 grams of bananas. The participants followed the exercise-and-banana protocol 3 times, on 3 different days, eating a different quantity of bananas each time. The study found that eating up to 300 grams of bananas caused a very small, but clinically meaningless, increase in plasma potassium concentration, 30 to 60 minutes after eating the bananas.[53] These results show that eating bananas is unlikely to treat or prevent a muscle cramp that is caused by potassium depletion. However, larger high-quality trials are needed to fully understand the role of potassium in muscle cramps and how to prevent/treat them.
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