The importance of potassium is highly underestimated.
This mineral is classified as an electrolyte because it’s highly reactive in water. When dissolved in water, it produces positively charged ions.
This special property allows it to conduct electricity, which is important for many processes throughout the body.
Interestingly, a potassium-rich diet is linked to many powerful health benefits. It may help reduce blood pressure and water retention, protect against stroke and help prevent osteoporosis and kidney stones (1, 2, 3, 4).
This article provides a detailed review of potassium and what it does for your health.
What Is Potassium?
Potassium is the third most abundant mineral in the body (5).
It helps the body regulate fluid, send nerve signals and regulate muscle contractions.
Roughly 98% of the potassium in your body is found in your cells. Of this, 80% is found in your muscle cells, while the other 20% can be found in your bones, liver and red blood cells (6).
Once inside your body, it functions as an electrolyte.
When in water, an electrolyte dissolves into positive or negative ions that have the ability to conduct electricity. Potassium ions carry a positive charge.
Your body uses this electricity to manage a variety of processes, including fluid balance, nerve signals and muscle contractions (7, 8).
Therefore, a low or high amount of electrolytes in the body can affect many crucial functions.
Potassium is an important mineral that functions as an electrolyte. It helps regulate fluid balance, nerve signals and muscle contractions.
It Helps Regulate Fluid Balance
The body is made of approximately 60% water (9).
40% of this water is found inside your cells in a substance called intracellular fluid (ICF).
The remainder is found outside your cells in areas such as your blood, spinal fluid and between cells. This fluid is called extracellular fluid (ECF).
Interestingly, the amount of water in the ICF and ECF is affected by their concentration of electrolytes, especially potassium and sodium.
Potassium is the main electrolyte in the ICF, and it determines the amount of water inside the cells. Conversely, sodium is the main electrolyte in the ECF, and it determines the amount of water outside the cells.
The number of electrolytes relative to the amount of fluid is called osmolality. Under normal conditions, the osmolality is the same inside and outside your cells.
Simply put, there’s an equal balance of electrolytes outside and inside your cells.
However, when osmolality is unequal, water from the side with fewer electrolytes will move into the side with more electrolytes to equalize electrolyte concentrations.
This may cause cells to shrink as water moves out of them, or swell up and burst as water moves into them (10).
That’s why it’s important to make sure you consume the right electrolytes, including potassium.
Maintaining good fluid balance is important for optimal health. Poor fluid balance can lead to dehydration, which in turn affects the heart and kidneys (11).
Eating a potassium-rich diet and staying hydrated can help maintain good fluid balance.
Fluid balance is affected by electrolytes, mainly potassium and sodium. Eating a potassium-rich diet can help you maintain a good fluid balance.
Potassium Is Important for the Nervous System
The nervous system relays messages between your brain and body.
These messages are delivered in the form of nerve impulses and help regulate your muscle contractions, heartbeat, reflexes and many other body functions (12).
Interestingly, nerve impulses are generated by sodium ions moving into cells and potassium ions moving out of cells.
The movement of ions changes the voltage of the cell, which activates a nerve impulse (13).
Unfortunately, a drop in blood levels of potassium can affect the body’s ability to generate a nerve impulse (6).
Getting enough potassium from your diet can help you maintain healthy nerve function.
This mineral plays an essential role in activating nerve impulses throughout your nervous system. Nerve impulses help regulate muscle contractions, the heartbeat, reflexes and many other processes.
Potassium Helps Regulate Muscle and Heart Contractions
The nervous system helps regulate muscle contractions.
However, altered blood potassium levels can affect nerve signals in the nervous system, weakening muscle contractions.
Both low and high blood levels can affect nerve impulses by altering the voltage of nerve cells (6, 14).
The mineral is also important for a healthy heart, as its movement in and out of cells helps maintain a regular heartbeat.
When blood levels of the mineral are too high, the heart may become dilated and flaccid. This can weaken its contractions and produce an abnormal heartbeat (8).
Likewise, low levels in the blood can also alter the heartbeat (15).
When the heart does not beat properly, it cannot effectively pump blood to the brain, organs and muscles.
In some cases, heart arrhythmia, or an irregular heartbeat, can be fatal and lead to sudden death (16).
Potassium levels have a significant effect on muscle contractions. Altered levels can cause muscle weakness, and in the heart, they may cause an irregular heartbeat.
Health Benefits of Potassium
Consuming a potassium-rich diet is linked to many impressive health benefits.
May Help Reduce Blood Pressure
High blood pressure affects nearly one in three Americans (17).
It’s a risk factor for heart disease, the leading cause of death worldwide (18).
A potassium-rich diet may reduce blood pressure by helping the body remove excess sodium (18).
High sodium levels can elevate blood pressure, especially for people whose blood pressure is already high (19).
An analysis of 33 studies found that when people with high blood pressure increased their potassium intake, their systolic blood pressure decreased by 3.49 mmHg, while their diastolic blood pressure decreased by 1.96 mmHg (1).
In another study including 1,285 participants aged 25–64, scientists found that people who ate the most potassium had reduced blood pressure, compared to people who ate the least.
Those who consumed the most had systolic blood pressure that was 6 mmHg lower and diastolic blood pressure that was 4 mmHg lower, on average (20).
May Help Protect Against Strokes
A stroke occurs when there is a lack of blood flow to the brain. It’s the cause of death for more than 130,000 Americans every year (21).
Several studies have found that eating a potassium-rich diet may help prevent strokes (1, 22).
In an analysis of 33 studies including 128,644 participants, scientists found that people who ate the most potassium had a 24% lower risk of stroke than people who ate the least (1).
Additionally, an analysis of 11 studies with 247,510 participants found that people who ate the most potassium had a 21% lower risk of stroke. They also found that eating a diet rich in this mineral was linked to a reduced risk of heart disease (22).
May Help Prevent Osteoporosis
Osteoporosis is a condition characterized by hollow and porous bones.
It’s often linked to low levels of calcium, an important mineral for bone health (23).
Interestingly, studies show that a potassium-rich diet may help prevent osteoporosis by reducing how much calcium the body loses through urine (24, 25, 26).
In a study in 62 healthy women aged 45–55, scientists found that people who ate the most potassium had the greatest total bone mass (2).
In another study with 994 healthy premenopausal women, scientists found that those who ate the most potassium had more bone mass in their lower back and hip bones (27).
May Help Prevent Kidney Stones
Kidney stones are clumps of material that may form in concentrated urine (28).
Calcium is a common mineral in kidney stones, and several studies show that potassium citrate lowers calcium levels in urine (29, 30).
In this way, potassium may help fight kidney stones.
Many fruits and vegetables contain potassium citrate, so it’s easy to add to your diet.
In a four-year study in 45,619 men, scientists found those who consumed the most potassium daily had a 51% lower risk of kidney stones (3).
Similarly, in a 12-year study in 91,731 women, scientists found that those who consumed the most potassium daily had a 35% lower risk of kidney stones (31).
It May Reduce Water Retention
Water retention happens when excess fluid builds up inside the body.
Historically, potassium has been used to treat water retention (32).
Studies suggest that a high potassium intake can help reduce water retention by increasing urine production and reducing sodium levels (4, 33, 34).
A potassium-rich diet may reduce blood pressure and water retention, protect against strokes and help prevent osteoporosis and kidney stones.
Sources of Potassium
Potassium is abundant in many whole foods, especially fruits, vegetables and fish.
Most health authorities agree that getting 3,500–4,700 mg of potassium daily appears to be the optimal amount (35, 36).
Here’s how much potassium you can get from eating a 3.5-ounce (100-gram) serving of foods rich in this mineral (37).
Beet greens, cooked: 909 mg
Yams, baked: 670 mg
Pinto beans, cooked: 646 mg
White potatoes, baked: 544 mg
Portobello mushrooms, grilled: 521 mg
Avocado: 485 mg
Sweet potato, baked: 475 mg
Spinach, cooked: 466 mg
Kale: 447 mg
Salmon, cooked: 414 mg
Bananas: 358 mg
Peas, cooked: 271 mg
On the other hand, over-the-counter supplements are not a great way to increase your potassium intake.
In many countries, food authorities limit potassium in over-the-counter supplements to 99 mg, which is much less than the amount you can get from just one serving of the potassium-rich whole foods above (38).
This 99-mg limit is likely because many studies have found that high doses of potassium from supplements may damage the gut and even lead to death by heart arrhythmia (38, 39, 40).
However, people who suffer from a potassium deficiency may receive a prescription from their doctor for a higher-dose supplement.
Potassium is found in a variety of fruits, vegetables and fish like salmon. Most health authorities suggest getting 3,500–4,700 mg of potassium daily.
Consequences of Too Much or Too Little Potassium
Less than 2% of Americans meet the US recommendations for potassium (41).
However, a low potassium intake will rarely cause a deficiency (42, 43).
Instead, deficiencies mostly happen when the body suddenly loses too much potassium. This may happen with chronic vomiting, chronic diarrhea or in other situations in which you’ve lost a lot of water (44).
It’s also uncommon to get too much potassium. Though it may happen if you take too many potassium supplements, there is no strong evidence that healthy adults can get too much potassium from foods (45).
Excess blood potassium mostly occurs when the body cannot remove the mineral through urine. Therefore, it mostly affects people with poor kidney function or chronic kidney disease (46).
Additionally, particular populations may need to limit their potassium intake, including those with chronic kidney disease, those taking blood pressure medications and elderly people, as kidney function normally declines with age (47, 48, 49).
However, there is some evidence that taking too many potassium supplements can be dangerous. Their small size makes them easy to overdose on (39, 40).
Consuming too many supplements at once may overcome the kidneys’ ability to remove excess potassium (50).
Nevertheless, it’s important to make sure you get enough potassium daily for optimal health.
This is especially true for older people, since high blood pressure, strokes, kidney stones and osteoporosis are more common among the elderly.
Potassium deficiencies or excess rarely occur through the diet. Despite this, maintaining an adequate potassium intake is important for your overall health.
The Bottom Line
Potassium is one of the most important minerals in the body.
It helps regulate fluid balance, muscle contractions and nerve signals.
What’s more, a high-potassium diet may help reduce blood pressure and water retention, protect against stroke and prevent osteoporosis and kidney stones.
Unfortunately, very few people get enough potassium. To get more in your diet, consume more potassium-rich foods, such as beet greens, spinach, kale and salmon.
An evidence-based nutrition article from our experts at Authority Nutrition.