Everything You Need To Know About Potassium

When it comes to potassium, it's important to discuss both how much you're consuming and what potassium levels are like in the blood. Potassium is a macromineral — a mineral that humans need in relatively large amounts for good health (via Medical News Today). It's an important electrolyte that works with sodium to control fluid balance in your body. It's also essential for nerve and muscle function. An adult's body contains about 45 millimoles (mmol) per kilogram of body weight, which means that a 175-pound adult has about 140 grams of potassium, located mostly in the fluid inside cells (via the National Institutes of Health). Potassium can be obtained from a variety of foods (particularly certain types of vegetables, legumes, and fruits) and supplements. Having too little or too much potassium in the body can be dangerous, and a number of health conditions may be affected by potassium levels.

Despite the importance of potassium, almost everyone is falling short of dietary guidelines for this mineral. According to the Oregon State University, survey data collected from 2007–2010 showed that 100% of American adults weren't consuming enough potassium to meet their body's needs. Data from 2011–2012 revealed that fewer than 3% of American adults are meeting the adequate intake (AI) level for potassium. Perhaps even more concerning, only about 5% of children ages one to three meet the AI for potassium, and less than 1% of children between the ages of four and five hit the recommended amount.

Potassium is an important electrolyte

Potassium is an electrolyte. As the Cleveland Clinic explains, "electrolytes are substances that have a natural positive or negative electrical charge when dissolved in water." Cells use electrolytes to transmit electrical charges, which are necessary for muscle and nerve function as well as many chemical reactions. Electrolytes also perform the critical task of maintaining fluid balance inside and outside of cells. Because they're so powerful, electrolyte levels are closely controlled by our bodies to ensure everything stays in the proper range. There are seven electrolytes; four with a positive charge (potassium, calcium, sodium, and magnesium) and three with a negative charge (chloride, phosphate, and bicarbonate).

Potassium's main job as an electrolyte is to maintain proper intracellular fluid levels (the amount of water inside a cell). It also plays an important role in nerve function, muscle contraction (including the heart), and kidney function (via the National Institutes of Health). There are a number of things that can throw your electrolytes out of whack. These include sweating from heavy exercise, vomiting, diarrhea, certain medications (including diuretics, laxatives, and antibiotics), heart failure, kidney disease, alcoholism, diabetes, eating disorders, and severe burns (via Healthline). Whatever the cause, it's important to replenish lost electrolytes, including potassium, to prevent potentially life-threatening health problems.

The relationship between potassium and sodium

While all electrolytes work together to create balance in your body, the relationship between potassium and sodium is particularly important (via the National Institutes of Health). Potassium is the electrolyte responsible for maintaining proper water levels inside cells (intracellular fluid volume), while sodium is responsible for maintaining water levels in the spaces between cells (extracellular fluid volume). The concentration of potassium is 30 times higher inside cells than outside of them, while sodium levels are much higher outside cells. Maintaining this balance — most potassium inside cells and most sodium outside them — creates a phenomenon called a membrane potential (via SF Gate). This membrane potential is what allows cells to use electrical charges to communicate with one another.

When blood levels of sodium go up, levels of potassium go down as the body attempts to maintain a difference between these two minerals inside and outside of cells (via University of Michigan Health). The reverse is also true: when potassium levels go up, sodium levels go down. But what does this biology lesson mean for your everyday life? The problem is that most Americans consume way too much sodium and not enough potassium (via the Centers for Disease Control and Prevention). As the American Heart Association (AHA) notes, consuming more potassium-rich foods can help your body get rid of excess sodium.

How much potassium we need and how much Americans are getting

Because it is so important, guidelines on how much potassium individuals should consume each day have been established (via the National Institutes of Health). These recommendations are expressed as an adequate intake (AI) level rather than a recommended dietary allowance (RDA). AIs are used to ensure nutritional needs are met when there isn't enough conclusive evidence to develop an RDA. The AI for infants 6 months and younger is 400 mg, while those age 7–12 months should get at least 860 mg. Children between 1 and 3 need 2,000 mg, and the AI increases to 2,300 mg between ages 4 and 8. Once puberty hits, males need more potassium than females. Between ages 9 and 13, boys' AI is 2,500 mg and girls' is 2,300 mg. Boys age 14–18 require 3,000 mg while girls in the same age group still only require 2,300 mg. From age 19 onward, adult men should aim to get 3,400 mg and women should shoot for at least 2,600 mg. Potassium needs increase during pregnancy and breastfeeding, with expecting mothers needing 2,900 mg per day and lactating women needing 2,800 mg. The daily value (DV) for potassium has been set at 4,700 mg by the FDA.

But how much potassium are Americans actually getting? Average potassium intake from food is only 3,016 mg for adult men and 2,320 mg for adult women — well below the AIs for this age group.

Who's at risk for not getting enough potassium?

Anyone can fall short of the adequate intake (AI) for potassium, but several groups are at particularly high risk for potassium deficiency (via the National Institutes of Health). Individuals with an inflammatory bowel disease (such as ulcerative colitis or Crohn's) may lose large amounts of potassium through both their damaged intestinal lining and frequent diarrhea. So even if they're consuming a lot of potassium-rich foods, these may not be enough to offset the increased losses.

People who use certain types of diuretics (to treat high blood pressure, for instance) are also at risk of low potassium levels because of increased potassium excretion in urine. (While potassium-sparing diuretics don't cause this problem, they can actually lead to the opposite problem: dangerously high levels of potassium.) Those who repeatedly use laxatives or enemas may also have low potassium levels because of increased potassium loss in stool.

Finally, people with pica, a condition in which individuals persistently eat non-food substances, can lead to potassium deficiency if clay is on the menu. That's because clay binds to potassium in the GI tract, preventing the body from properly absorbing the mineral.

Food sources of potassium

Although bananas have become the poster child for potassium, this mineral is found in a wide variety of plant and animal food sources (via the National Institutes of Health). Fruits (especially dried) and vegetables are particularly high in potassium, as are some legumes. Whole grains contain more potassium than their refined counterparts (think brown rice versus white rice). Individuals are able to absorb about 85–90% of the potassium they consume. The majority of potassium in American adults' diets comes from milk, coffee, tea, other nonalcoholic beverages, and potatoes. Dietary potassium comes in several forms, including potassium phosphate, potassium sulfate, and potassium citrate. Potassium chloride, a type of salt, is also used in processed foods as a flavor enhancer, thickener, stabilizer, and firming agent (via Livestrong). Potassium chloride appears to have the same effects as naturally occurring forms of potassium, but it tends to be used in very small amounts because of its bitter flavor.

According to the Dietary Guidelines for Americans, cooked beet greens are the richest source of potassium, containing 1,309 mg per cup. Other excellent sources include lima beans (969 mg/cup), baked potato (926 mg per medium spud), and acorn squash (896 mg/cup). Orange juice contains 496 mg per cup. Plain nonfat yogurt contains 625 mg per 8 ounces, while clams are the most potassium-rich meat (containing 534 mg per 3-ounce serving). For comparison, a medium banana contains only 451 mg.

Potassium supplements

Potassium can also be obtained from dietary supplements (via the National Institutes of Health). Potassium can be included in a multivitamin or as a standalone supplement. Supplements come in a variety of forms, including tablets, capsules, and liquids. Potassium chloride is most commonly used, but other forms you may see on a package's label include potassium citrate, potassium phosphate, potassium aspartate, potassium bicarbonate, and potassium gluconate. Each of these contain a different percentage of elemental potassium, and this is what is included on the Supplement Facts panel. Potassium isn't always included in a multivitamin, and when it is, it's usually only about 80 mg. Even potassium-only supplements usually contain no more than 99 mg — a miniscule amount, compared to the 2,600–3,400 mg adults need daily. Manufacturers usually limit the amount of potassium in supplements to less than 99 mg because of safety concerns related to higher levels potentially causing lesions in the small intestines. Research suggests that as much as 94% of the potassium in supplements may be absorbed by the body.

According to national survey data, only about 12% of adults and children aged 2 and over use supplements containing potassium. Because most supplements contain so little of this mineral, supplementation adds an average of only 87 mg to total daily potassium intake.

How potassium levels are controlled

Because it's a powerful electrolyte, circulating potassium levels are tightly controlled by the body. The normal range for potassium is a narrow 3.6–5.2 mmol/L, although some labs may use slightly different ranges (via WebMD). According to the Merck Manual, "the body maintains the right level of potassium by matching the amount of potassium consumed with the amount lost." Potassium is mostly lost in urine, although small amounts are lost in the stool and through sweating. As Merck notes, "healthy kidneys can adjust the excretion of potassium to match changes in consumption." Indeed, as a 2017 paper published in the International Journal of Clinical and Experimental Physiology explained, when too much potassium is lost through urine, some of the potassium inside cells is pushed out into the blood in order to ensure balance.

Aldosterone is the hormone responsible for overseeing potassium balance in the body (via You and Your Hormones). It's a type of steroid produced by the cortex (outer layer) of the adrenal glands. According to You and Your Hormones, aldosterone "plays a central role in the regulation of blood pressure mainly by acting on organs such as the kidney and the colon to increase the amount of salt (sodium) reabsorbed into the bloodstream and to increase the amount of potassium excreted in the urine." Having either too little or too much aldosterone can negatively impact potassium levels in the blood.

When potassium levels are too high

High levels of potassium, or hyperkalemia, occur when there's so much excess potassium in your body that your kidneys can't keep up with the task of filtering it out of the blood (via the Cleveland Clinic). Hyperkalemia can happen to anyone, but individuals with certain medical conditions, including kidney disease, diabetes, HIV, congestive heart failure, Addison's disease, and severe burns over a large portion of the body are at particularly high risk. People who use certain medications, including particular types of drugs to treat high blood pressure, also have an increased chance of getting hyperkalemia. While eating a lot of high-potassium foods may lead to hyperkalemia, dietary supplements or use of potassium-containing salt substitutes are much more likely to cause the condition.

Mild to moderate hyperkalemia often doesn't have any symptoms, or symptoms are vague and come and go. When they do occur, symptoms may include abdominal pain, nausea, muscle weakness, chest pain, and heart palpitations. Very high potassium levels can cause the sudden onset of heart rhythm changes, which can lead to heart attack and death. Treatments for hyperkalemia include diuretics, fluid therapy, the use of drugs called potassium binders, and changes to medication if necessary. Those who've been diagnosed with hyperkalemia or who are at increased risk may also need to avoid or limit high-potassium foods.

When potassium levels are too low

Circulating levels of potassium can become too low — a condition known as hypokalemia (via the Cleveland Clinic). There are a number of reasons this can happen. Hypokalemia can be caused by not consuming enough potassium, but this isn't very common. More often, low potassium levels are caused by frequent vomiting or diarrhea, excessive sweating, drinking too much alcohol, or taking certain medications (including diuretics, antibiotics, and corticosteroids). In rare cases, hypokalemia can result from adrenal disorders, kidney disease, colon polyps, and certain genetic disorders such as Bartter's syndrome and Liddle syndrome.

As with high potassium levels, mildly low potassium levels often don't cause any symptoms. When symptoms do occur, they include muscle twitches, cramps, weakness, or paralysis, as well as kidney problems and abnormal heart rhythm. Treatment for hypokalemia involves restoring normal blood potassium levels through supplementation. In severe cases, this may be done intravenously. It's also important to address the underlying cause of the low potassium levels in order to prevent problems in the future.

Mild hypokalemia is relatively common. According to a 2018 paper published in Endocrine Connections, about 14% of Americans have been found to have the condition when undergoing routine bloodwork. About 80% of individuals taking diuretics will become hypokalemic. Fortunately, severe hypokalemia (which, like hyperkalemia, can cause life-threatening changes to heart rhythm) is rare.

Potassium and medications

There are a variety of therapeutic drugs that have the potential to negatively affect potassium levels (via GoodRx). Certain kinds of medicines have the potential to cause low potassium levels (hypokalemia). Diuretics are the most common cause of medication-induced hypokalemia. These are commonly used to treat high blood pressure, heart failure, and swelling in the limbs, but because they increase urine production, they can lead to excess loss of potassium. Too much potassium may be lost in stool if laxatives and enemas are overused. Since insulin drives potassium from the bloodstream into cells, high doses can lead to low circulating levels of this mineral. This is why the asthma drug Albuterol — which stimulates the production of insulin — can cause low potassium levels. The decongestant pseudoephedrine also pushes potassium into cells, potentially lowering blood concentrations to dangerous levels.

Other medications can cause high potassium levels (hyperkalemia). Angiotensin II receptor blockers (ARBs) and angiotensin converting enzyme (ACE) inhibitors — two classes of drugs prescribed to treat high blood pressure — can cause your kidneys to retain potassium, leading to hyperkalemia. In fact, as many as 10% of people taking ARBs will experience at least mild hyperkalemia. In an effort to minimize this danger, many ARBs and ACEs are combined with hydrochlorothiazide (HCTZ), which lowers potassium levels. Spironolactone, a potassium-sparing diuretic prescribed to treat acne and PCOS, can also cause high potassium levels. Heparin (a blood thinner used to treat blood clots) and cyclosporine and tacrolimus (anti-rejection medications used after an organ transplant) can also lead to hyperkalemia.

Potassium and blood pressure

According to the Centers for Disease Control and Prevention (CDC), 47% of American adults have high blood pressure, defined as a reading of 130/80 mmHg or higher. High blood pressure, or hypertension, may not have any obvious symptoms, but it's a major risk factor for heart disease and stroke, both of which are among the leading causes of death in the United States.

Potassium can lower blood pressure in two ways (via the National Institutes of Health). It's a vasodilator, which means it helps keep blood vessels open, and it also encourages increased excretion of sodium by the kidneys. In fact, the Dietary Approaches to Stop Hypertension (DASH) eating plan used to prevent and correct hypertension provides about three times the amount of potassium as what's in the standard American diet. But the DASH diet also includes large amounts of other heart-healthy minerals like magnesium and calcium, so it's impossible to say how much credit should go to potassium specifically. Recent meta-analyses have concluded that potassium supplements may lower systolic blood pressure (the top number in a blood pressure reading, corresponding to the pressure in the arteries when the heart is contracting) by as much as 4.48–6.8 mmHg and diastolic blood pressure (the bottom number in a blood pressure reading, corresponding to the pressure in the arteries when the heart is relaxed between beats) by 2.96–4.6 mmHg. Other studies, however, have found no strong link between potassium intake and hypertension.

Potassium and bone health

Although calcium tends to get all the attention when it comes to minerals that build and maintain strong bones, potassium also appears to help prevent osteoporosis. Osteoporosis is a condition in which the bones become thin, weak, and prone to fractures. According to the National Osteoporosis Foundation, 10 million Americans have osteoporosis and another 44 million have osteopenia (low bone density). And if you think osteoporosis is something you don't need to worry about until you're much older, think again. As WebMD explains, bone thinning can happen at any age and often has no symptoms until the first broken bone.

A 2020 paper published in Nutrition Research and Practice outlined two ways in which potassium can help preserve bone mineral density. Higher intakes of potassium appear to decrease the amount of bone-building calcium that's lost in urine. The pH of our blood is very tightly controlled, but the standard Western diet has an acidifying effect. To counter this, bones release calcium, which is alkaline, into the bloodstream to restore pH balance. Consuming plenty of potassium, which is also alkaline, may help maintain pH balance without having to strip calcium from the bones. The National Institutes of Health (NIH) caution, however, that research in this area is limited and more studies are needed to better understand the link between potassium and bone health.

Potassium and blood sugar regulation

Insulin is the chief hormone that regulates blood sugar levels, and according to the NIH, potassium is needed for insulin secretion from the pancreas. Low potassium levels may therefore lead to low insulin production, which can cause blood sugar levels to rise. This is usually seen among individuals using diuretics (particularly those containing thiazides) long-term. The NIH notes that "numerous observational studies of adults have found associations between lower potassium intakes or lower serum or urinary potassium levels and increased rates of fasting glucose, insulin resistance, and type 2 diabetes." This connection appears to be stronger among African Americans than whites. The NIH cautioned, however, that more research is needed to better understand this link.

The connection between low potassium levels and diabetes runs both ways. Those with poorly managed diabetes can experience diabetic ketoacidosis, a condition in which there isn't enough insulin to drive glucose into the cells, so the body begins breaking down fat for fuel (via WebMD). This breakdown releases chemicals called ketones, which can build up to life-threatening levels. The ketones and high blood sugar of diabetic ketoacidosis lead to increased potassium loss through the kidneys, and the insulin and fluids used to treat diabetic ketoacidosis can inadvertently cause potassium levels to drop even lower.

Potassium and kidney stones

Kidney stones are a medical condition that most likely aren't on your radar, but they probably should be. These painful stones will affect about 11% of men and 9% of women at least once during their lifetime (via the National Kidney Foundation). A number of substances can crystalize in the kidneys, but according to a 2006 paper published in the Canadian Medical Association Journal, the vast majority of stones — about 80% — are calcium-based.

Low potassium levels make it harder for calcium to be reabsorbed into the blood in the kidneys, which causes calcium levels to build up in the kidneys and urine (via the National Institutes of Health). The more calcium, the greater the risk of calcium-based kidney stones. There appears to be an inverse relationship between the amount of dietary potassium an individual consumes and their risk for kidney stones. According to one large study, those who consumed 4,042 mg or more of potassium a day were 51% less likely to get kidney stones compared to those who consumed 2,895 mg or less of potassium daily. Some studies have found a link between potassium citrate supplementation and decreased risk for calcium-based kidney stones, although it appears that it's the citrate, not the potassium, that deserves the credit.