foods high in potassium

What is Potassium

Potassium is a mineral that is vital to cell metabolism. Potassium is a type of electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the water-electrolyte balance 1). Potassium is present in all body tissues and is required for normal cell function because of its role in maintaining intracellular fluid volume and transmembrane electrochemical gradients 2). Potassium helps transport nutrients into cells and removes waste products out of cells. Potassium is also important in muscle function, helping to transmit messages between nerves and muscles.

Potassium, along with other electrolytes such as sodium, chloride, and bicarbonate (total CO2), helps regulate the amount of fluid in the body and maintains a stable acid-base balance. Potassium is present in all body fluids, but most potassium is found within the cells. Only a small amount is present in fluids outside the cells and in the liquid part of the blood (called serum or plasma).

The total amount of potassium in the adult body is about 45 millimole (mmol)/kg body weight (about 140 g for a 175 pound adult; 1 mmol = 1 milliequivalent [mEq] or 39.1 mg potassium) 3). Most potassium resides intracellularly, and a small amount is in extracellular fluid. The intracellular concentration of potassium is about 30 times higher than the extracellular concentration, and this difference forms a transmembrane electrochemical gradient that is maintained via the sodium-potassium (Na+/K+) ATPase transporter 4). In addition to maintaining cellular tonicity, this gradient is required for proper nerve transmission, muscle contraction, and kidney function.

You get most of the potassium you need from the foods that you eat and most people have an adequate intake of potassium. The body uses what it requires and the kidneys eliminate the rest in the urine. The body tries to keep the blood potassium level within a very narrow range. Levels are mainly controlled by aldosterone, a hormone produced by the adrenal glands in the kidneys.

Potassium is absorbed via passive diffusion, primarily in the small intestine 5). About 90% of ingested potassium is absorbed and used to maintain its normal intracellular and extracellular concentrations 6). Potassium is excreted primarily in the urine, some is excreted in the stool, and a very small amount is lost in sweat. The kidneys control potassium excretion in response to changes in dietary intakes, and potassium excretion increases rapidly in healthy people after potassium consumption, unless body stores are depleted 7). The kidneys can adapt to variable potassium intakes in healthy individuals, but a minimum of 5 mmol (about 195 mg) potassium is excreted daily in urine 8). This, combined with other obligatory losses, suggests that potassium balance cannot be achieved with intakes less than about 400–800 mg/day.

Assessing potassium status is not routinely done in clinical practice, and it is difficult to do because most potassium in the body is inside cells. Although blood potassium levels can provide some indication of potassium status, they often correlate poorly with tissue potassium stores 9). Other methods to measure potassium status include collecting balance data (measuring net potassium retention and loss); measuring the total amount of potassium or the total amount of exchangeable potassium in the body; and conducting tissue analyses (e.g., muscle biopsies), but all have limitations 10).

Normal serum concentrations of potassium range from about 3.6 to 5.0 mmol/L and are regulated by a variety of mechanisms 11). Diarrhea, vomiting, kidney disease, use of certain medications, and other conditions that alter potassium excretion or cause transcellular potassium shifts can cause hypokalemia (serum levels below 3.6 mmol/L) or hyperkalemia (serum levels above 5.0 mmol/L) 12). Otherwise, in healthy individuals with normal kidney function, abnormally low or high blood levels of potassium are rare.

Because the blood concentration of potassium is so small, minor changes can have significant consequences. If potassium levels are too low or too high, there can be serious health consequences; a person may be at risk for developing shock, respiratory failure, or heart rhythm disturbances. An abnormal potassium level can alter the function of the nerves and muscles; for example, the heart muscle may lose its ability to contract.

Your body needs potassium to:

  • Build proteins
  • Break down and use carbohydrates
  • Build muscle
  • Maintain normal body growth
  • Control the electrical activity of the heart
  • Control the acid-base balance

Reduced potassium consumption has been associated with hypertension and cardiovascular diseases, and appropriate consumption levels could be protective
against these conditions 13). A recent meta-analysis including 11 cohort studies reported an inverse association between potassium intake and risk of stroke 14). Additionally, two meta-analyses of trials comparing increased potassium to lower potassium intake found that increased potassium intake lowers blood pressure
15), 16). These results were further supported by a systematic review without a meta-analysis, which concluded
that increased potassium intake results in decreased blood pressure in adults 17). Thus, a public health intervention aimed at increasing potassium intake from food could be a cost-effective strategy to reduce the burden of cardiovascular morbidity and mortality. Moreover, increasing potassium consumption from food in the population is safe; in individuals without renal impairment caused by medical conditions or drug therapy, the body is able to efficiently adapt and excrete excess potassium via the urine when consumption 18).

The American Heart Association recommended potassium intake for an average adult is 4,700 milligrams (mg) per day. Most of us aren’t getting nearly that much. On average, adult males eat almost 3,200 mg/day, and adult females eat about 2,400 mg/day 19). Remember that potassium is only part of an overall heart-healthy eating pattern. Other dietary factors that may affect blood pressure include amount and type of dietary fat; cholesterol; protein, sugar and fiber; calcium and magnesium, and of course, sodium.

For example, the DASH (Dietary Approaches to Stop Hypertension) diet study found that a diet rich in fruits, vegetables, fat-free or low-fat (1 percent) milk and milk products, whole-grain foods, fish, poultry, beans, seeds and unsalted nuts reduced blood pressure compared to a typical American diet. The DASH eating plan also had less sodium; sweets, added sugars and sugar-containing beverages; saturated and trans fats; and red meats than the typical American diet.

People with kidney problems, especially those on dialysis, should not eat too many potassium-rich foods. The health care provider will recommend a special diet.

Mechanism of Action of Potassium

Potassium is the major cation (positive ion) inside animal cells, while sodium is the major cation outside animal cells. The concentration differences of these charged particles causes a difference in electric potential between the inside and outside of cells, known as the membrane potential. The balance between potassium and sodium is maintained by ion pumps in the cell membrane. The cell membrane potential created by potassium and sodium ions allows the cell generate an action potential–a “spike” of electrical discharge. The ability of cells to produce electrical discharge is critical for body functions such as neurotransmission, muscle contraction, and heart function. Potassium is also an essential mineral needed to regulate water balance, blood pressure and levels of acidity 20). The more potassium you eat, the more sodium you pass out of the body through urine. Increased potassium intake has no adverse effect on blood lipid concentration, catecholamine concentrations, or renal function in apparently healthy adults without impaired renal handling of potassium 21). The largest benefit was detected when sodium intake was more than 4 g/day, which is the intake of most populations globally 22), so increased potassium intake should benefit most people in most countries. However, the authors also found a statistically significant decrease in blood pressure with increased potassium when sodium intake was 2-4 g/day. Therefore, increased potassium can continue to be beneficial in terms of blood pressure even as individuals and populations decrease their sodium intake. Studies examining both nutrients simultaneously support this concept, showing an increased benefit with simultaneous reduction in sodium and increase in potassium compared with changes in one nutrient individually 23), 24).

Potassium also helps relax blood vessel walls, which helps lower blood pressure 25).

World Health Organization recommends an increase in potassium intake from food to reduce blood pressure and risk of cardiovascular disease, stroke and coronary heart disease in adults. World Health Organization suggests a potassium intake of at least 90 mmol/day (3510 mg/day) for adults (conditional recommendation) 26).

Physiologically, potassium exists as an ion in the body. Potassium (K+) is a positively charged electrolyte, cation, which is present throughout the body in both intracellular and extracellular fluids. The majority of body potassium, > 90%, are intracellular. It moves freely from intracellular fluid (ICF) to extracellular fluid (ECF) and vice versa when adenosine triphosphate (ATP) increases the permeability of the cell membrane. It is mainly replaced inside or outside the cells by another cation, sodium (Na+). The movement of potassium into or out of the cells is linked to certain body hormones and also to certain physiological states. Standard laboratory tests measure ECF potassium. Potassium enters the body rapidly during food ingestion. Insulin is produced when a meal is eaten; this causes the temporary movement of potassium from ECF to ICF. Over the ensuing hours, the kidneys excrete the ingested potassium and homeostasis is returned. In the critically ill patient, suffering from hyperkalaemia, this mechanism can be manipulated beneficially by administering high concentration (50%) intravenous glucose. Insulin can be added to the glucose, but glucose alone will stimulate insulin production and cause movement of potassium from ECF to ICF. The stimulation of alpha receptors causes increased movement of potassium from ICF to ECF. A noradrenaline infusion can elevate serum potassium levels. An adrenaline infusion, or elevated adrenaline levels, can lower serum potassium levels. Metabolic acidosis causes a rise in extracellular potassium levels. In this situation, excess of hydrogen ions (H+) are exchanged for intracellular potassium ions, probably as a result of the cellular response to a falling blood pH. Metabolic alkalosis causes the opposite effect, with potassium moving into the cells 27).

What is the recommended dietary potassium intake?

Intake recommendations for potassium and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by an expert committee of the Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine 28). Dietary Reference Intake (DRI) is the general term for a set of reference values used for planning and assessing nutrient intakes of healthy people. These values, which vary by age and sex, include:

  • Recommended Dietary Allowance (RDA): Average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals; often used to plan nutritionally adequate diets for individuals.
  • Adequate Intake (AI): Intake at this level is assumed to ensure nutritional adequacy; established when evidence is insufficient to develop an RDA.
  • Estimated Average Requirement (EAR): Average daily level of intake estimated to meet the requirements of 50% of healthy individuals; usually used to assess the nutrient intakes of groups of people and to plan nutritionally adequate diets for them; can also be used to assess the nutrient intakes of individuals.
  • Tolerable Upper Intake Level (UL): Maximum daily intake unlikely to cause adverse health effects.

When the Food and Nutrition Board evaluated the available data in 2005, it found the data insufficient to derive an EAR for potassium, so the board established AIs for all ages based on potassium intakes in healthy populations 29). Table 2 lists the current AIs for potassium for healthy individuals. The Food and Nutrition Board is reevaluating the DRIs for potassium and expects to release a new report with its findings in 2019.

Table 1: Adequate Intakes (AIs) for Potassium*

AgeMaleFemalePregnancyLactation
Birth to 6 months400 mg400 mg
7–12 months700 mg700 mg
1–3 years3,000 mg3,000 mg
4–8 years3,800 mg3,800 mg
9–13 years4,500 mg4,500 mg
14–18 years4,700 mg4,700 mg4,700 mg5,100 mg
19–50 years4,700 mg4,700 mg4,700 mg5,100 mg
51+ years4,700 mg4,700 mg

*The AIs do not apply to individuals with impaired potassium excretion because of medical conditions (e.g., kidney disease) or the use of medications that impair potassium excretion.

[Source 30)]
Potassium rich foods

Potassium Intakes and Status of Americans

Dietary surveys consistently show that people in the United States consume substantially less potassium than recommended, which is why the 2015–2020 Dietary Guidelines for Americans identifies potassium as a “nutrient of public health concern” 31). According to data from the 2013–2014 National Health and Nutrition Examination Survey (NHANES), the average daily potassium intake from foods is 2,423 mg for males aged 2–19, and 1,888 mg for females aged 2–19 32). In adults aged 20 and over, the average daily potassium intake from foods is 3,016 mg for men and 2,320 mg for women.

Average potassium intakes vary by race. Non-Hispanic blacks aged 20 and older consume an average of 2,449 mg potassium per day. Average daily intakes are 2,695 mg for Hispanic whites and 2,697 mg for non-Hispanic whites 33).

Use of potassium-containing dietary supplements does not significantly increase total potassium intakes among U.S. adults 34), probably because most potassium-containing dietary supplements provide no more than 99 mg potassium per serving 35). Data from NHANES 2013–2014 indicate that 12% of children and adults aged 2 and over use supplements containing potassium, and among those who do, supplement use adds a mean of only 87 mg to total daily potassium intakes 36).

Potassium supplements

In dietary supplements, potassium is often present as potassium chloride, but many other forms—including potassium citrate, phosphate, aspartate, bicarbonate, and gluconate—are also used 37). The Supplement Facts panel on a dietary supplement label declares the amount of elemental potassium in the product, not the weight of the entire potassium-containing compound. Some dietary supplements contain potassium iodide in microgram amounts, but this ingredient serves as a form of the mineral iodine, not potassium.

Not all multivitamin/mineral supplements contain potassium, but those that do typically provide about 80 mg potassium 38). Potassium-only supplements are also available, and most contain up to 99 mg potassium. Information on many dietary supplements that contain potassium is available in the Dietary Supplement Label Database 39) from the National Institutes of Health, which contains label information from tens of thousands of dietary supplement products on the market.

Many dietary supplement manufacturers and distributors limit the amount of potassium in their products to 99 mg (which is only about 3% of the DV) because of two concerns related to potassium-containing drugs. First, the FDA has ruled that some oral drug products that contain potassium chloride and provide more than 99 mg potassium are not safe because they have been associated with small-bowel lesions 40). Second, the FDA requires some potassium salts containing more than 99 mg potassium per tablet to be labeled with a warning about the reports of small-bowel lesions 41). In accordance with a ruling by Congress, the FDA may not limit the amount of any nutrient, including potassium, in a dietary supplement, except for safety-related reasons 42). However, the FDA has not issued a ruling about whether dietary supplements containing more than 99 mg potassium must carry a warning label 43).

Only a few studies have examined how well the various forms of potassium in dietary supplements are absorbed. A 2016 dose-response trial found that humans absorb about 94% of potassium gluconate in supplements, and this absorption rate is similar to that of potassium from potatoes 44). According to an older study, liquid forms of potassium chloride (used as drugs to treat conditions such as digitalis intoxication or arrhythmias due to hypokalemia) are absorbed within a few hours 45). Enteric coated tablet forms of potassium chloride (designed to prevent dissolution in the stomach but allow it in the small intestine) are not absorbed as rapidly as liquid forms 46).

Salt substitutes

Many salt substitutes contain potassium chloride as a replacement for some or all of the sodium chloride in salt. The potassium content of these products varies widely, from about 440 mg to 2,800 mg potassium per teaspoon 47). Some people, such as those with kidney disease or who are taking certain medications, should consult their healthcare provider before taking salt substitutes because of the risk of hyperkalemia posed by the high levels of potassium in these products.

Foods high in Potassium

Potassium is found in a wide variety of plant and animal foods and in beverages. Many fruits and vegetables are excellent sources, as are some legumes (e.g., soybeans) and potatoes. Meats, poultry, fish, milk, yogurt, and nuts also contain potassium 48). Among starchy foods, whole-wheat flour and brown rice are much higher in potassium than their refined counterparts, white wheat flour and white rice 49).

Milk, coffee, tea, other nonalcoholic beverages, and potatoes are the top sources of potassium in the diets of U.S. adults 50). Among children in the United States, milk, fruit juice, potatoes, and fruit are the top sources 51).

It is estimated that the body absorbs about 85%–90% of dietary potassium 52). The forms of potassium in fruits and vegetables include potassium phosphate, sulfate, citrate, and others, but not potassium chloride 53).

Selected food sources of potassium are listed in Table 2.

Table 2: Selected Food Sources of Potassium

FoodMilligrams
(mg) per
serving
Percent
DV*
Apricots, dried, ½ cup1,10131
Lentils, cooked, 1 cup73121
Prunes, dried, ½ cup69920
Squash, acorn, mashed, 1 cup64418
Raisins, ½ cup61818
Potato, baked, flesh only, 1 medium61017
Kidney beans, canned, 1 cup60717
Orange juice, 1 cup49614
Soybeans, mature seeds, boiled, ½ cup44313
Banana, 1 medium42212
Milk, 1%, 1 cup36610
Spinach, raw, 2 cups33410
Chicken breast, boneless, grilled, 3 ounces3329
Yogurt, fruit variety, nonfat, 6 ounces3309
Salmon, Atlantic, farmed, cooked, 3 ounces3269
Beef, top sirloin, grilled, 3 ounces3159
Molasses, 1 tablespoon3089
Tomato, raw, 1 medium2928
Soymilk, 1 cup2878
Yogurt, Greek, plain, nonfat, 6 ounces2407
Broccoli, cooked, chopped, ½ cup2297
Cantaloupe, cubed, ½ cup2146
Turkey breast, roasted, 3 ounces2126
Asparagus, cooked, ½ cup2026
Apple, with skin, 1 medium1956
Cashew nuts, 1 ounce1875
Rice, brown, medium-grain, cooked, 1 cup1544
Tuna, light, canned in water, drained, 3 ounces1534
Coffee, brewed, 1 cup1163
Lettuce, iceberg, shredded, 1 cup1023
Peanut butter, 1 tablespoon903
Tea, black, brewed, 1 cup883
Flaxseed, whole, 1 tablespoon842
Bread, whole-wheat, 1 slice812
Egg, 1 large692
Rice, white, medium-grain, cooked, 1 cup542
Bread, white, 1 slice371
Cheese, mozzarella, part skim, 1½ ounces361
Oil (olive, corn, canola, or soybean), 1 tablespoon00

*DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration (FDA) to help consumers compare the nutrient contents of products within the context of a total diet. The DV for potassium used as the basis for the values in Table 2 is 3,500 mg for adults and children aged 4 and older, but the DV will increase to 4,700 mg when the updated Nutrition and Supplement Facts labels are implemented 54))). The updated labels and DVs must appear on food products and dietary supplements beginning in January 2020, but they can be used now 55). Foods providing 20% or more of the DV are considered to be high sources of a nutrient.

[Source 56)]

The U.S. Department of Agriculture’s Nutrient Database 57) lists the nutrient content of many foods and provides a comprehensive list of foods containing potassium ordered by food name 58) and by nutrient content 59). The 2015–2020 Dietary Guidelines for Americans 60) provides a list of foods with at least 5% of the DV for potassium per serving.

People with kidney problems, especially those on dialysis, should not eat too many potassium-rich foods. The health care provider will recommend a special diet.

potassium rich foods

(Source 61)).

Benefits of Potassium

Because of potassium’s wide-ranging roles in the body, low intakes can increase the risk of illness. This section focuses on four diseases and disorders in which potassium might be involved: hypertension and stroke; kidney stones; bone health; and blood glucose control and type 2 diabetes.

Hypertension and stroke

Hypertension, a major risk factor for heart disease and stroke, affects almost a third of Americans. According to an extensive body of literature, low potassium intakes increase the risk of hypertension, especially when combined with high sodium intakes 62). Higher potassium intakes, in contrast, may help decrease blood pressure, in part by increasing vasodilation and urinary sodium excretion, which in turn reduces plasma volume 63); this effect may be most pronounced in salt-sensitive individuals 64).

The Dietary Approaches to Stop Hypertension (DASH) eating pattern, which emphasizes potassium from fruits, vegetables, and low-fat dairy products, lowers systolic blood pressure by an average of 5.5 mmHg and diastolic blood pressure by 3.0 mmHg 65). The DASH eating pattern provides three times more potassium than the average American diet. However, it also increases intakes of other nutrients, such as magnesium and calcium, that are also associated with reductions in blood pressure, so potassium’s independent contribution cannot be determined.

Results from most clinical trials suggest that potassium supplementation reduces blood pressure. A 2017 meta-analysis of 25 randomized controlled trials in 1,163 participants with hypertension found significant reductions in systolic blood pressure (by 4.48 mm Hg) and diastolic blood pressure (by 2.96 mmHg) with potassium supplementation, mostly as potassium chloride at 30–120 mmol/day potassium (1,173–4,692 mg), for 4–15 weeks 66). Another meta-analysis of 15 randomized controlled trials found that potassium supplements (mostly containing potassium chloride at 60–65 mEq/day potassium [2,346–2,541 mg]) for 4–24 weeks in 917 patients with normal blood pressure or hypertension who were not taking antihypertensive medications significantly reduced both systolic and diastolic blood pressure 67). The supplements had the greatest effect in patients with hypertension, reducing systolic blood pressure by a mean of 6.8 mmHg and diastolic blood pressure by 4.6 mmHg. Two earlier meta-analyses of 19 trials 68) and 33 trials 69) had similar findings. However, a Cochrane review of six of the highest-quality trials found nonsignificant reductions in systolic and diastolic blood pressure with potassium supplementation 70).

In 2017, the Agency for Healthcare Research and Quality (AHRQ) published a draft systematic review of the effects of sodium and potassium intakes on chronic disease outcomes and their risk factors 71). The authors concluded that, based on observational studies, higher potassium intakes were not associated with lower blood pressure in adults or with the risk of hypertension 72). The authors did report, however, that potassium supplements (mostly containing potassium chloride) in doses ranging from 20 to 129 mmol/day (782 to 5,044 mg/day) for 1 to 36 months significantly lowered systolic blood pressure by a mean of 6.04 mmHg and diastolic blood pressure by 3.43 mmHg in adults, most of whom had hypertension 73). Based on 13 randomized controlled trials that primarily enrolled patients with hypertension, the review found that the use of potassium-containing salt substitutes in place of sodium chloride significantly reduced systolic blood pressure in adults by a mean of 5.34 mmHg and diastolic blood pressure by 2.62 mmHg. However, reducing sodium intake decreased both systolic and diastolic blood pressure in adults, and increasing potassium intake via food or supplements did not reduce blood pressure any further. This finding suggests that at least some of the beneficial effects of potassium salt substitutes on blood pressure may be due to the accompanying reduction in sodium intake, rather than the increase in potassium intake 74).

Higher potassium intakes have been associated with a decreased risk of stroke and possibly other cardiovascular diseases (CVDs) 75). A meta-analysis of 11 prospective cohort studies in 247,510 adults found that a 1,640 mg per day higher potassium intake was associated with a significant 21% lower risk of stroke as well as nonsignificant lower risks of coronary heart disease and total CVD 76). Similarly, the authors of a meta-analysis of 9 cohort studies reported a significant 24% lower risk of stroke with higher potassium intakes and a nonsignificant reduction in coronary heart disease and cardiovascular disease (CVD) risk 77). However, a draft Agency for Healthcare Research and Quality report found inconsistent relationships between dietary potassium intakes and risk of stroke based on 1 case-cohort and 10 prospective cohort studies 78).

Any beneficial effect of potassium on cardiovascular disease (CVD) is likely due to its antihypertensive effects. However, some research shows a benefit even when blood pressure is accounted for. For example, a 2016 meta-analysis of 16 cohort studies with a total of 639,440 participants found that those with the highest potassium intakes (median 103 mmol [4,027 mg] per day) had a 15% lower risk of stroke than those with the lowest potassium intakes (median 52.5 mmol [2,053 mg] per day). In addition, participants who consumed 90 mmol potassium/day (approximately 3,500 mg) had the lowest risk of stroke 79). However, even when blood pressure was accounted for, higher potassium intakes still produced a significant 13% lower risk of stroke. These findings suggest that other mechanisms (e.g., improved endothelial function and reduced free radical formation) may be involved 80).

The FDA has approved the following health claim: “Diets containing foods that are a good source of potassium and that are low in sodium may reduce the risk of high blood pressure and stroke” 81). Overall, the evidence suggests that consuming more potassium might have a favorable effect on blood pressure and stroke, and it might also help prevent other forms of cardiovascular disease. However, more research on both dietary and supplemental potassium is needed before firm conclusions can be drawn.

Kidney stones

Kidney stones are most common in people aged 40 to 60 82). Stones containing calcium—in the form of calcium oxalate or calcium phosphate—are the most common type of kidney stone. Low potassium intakes impair calcium reabsorption within the kidney, increasing urinary calcium excretion and potentially causing hypercalciuria and kidney stones 83). Low urinary levels of citrate also contribute to kidney stone development.

Observational studies show inverse associations between dietary potassium intakes and risk of kidney stones. In a cohort of 45,619 men aged 40 to 75 years with no history of kidney stones, those with the highest potassium intakes (≥4,042 mg/day on average) had a 51% lower risk of kidney stones over 4 years of follow-up than those with the lowest intakes (≤2,895 mg/day) 84). Similarly, in over 90,000 women aged 34–59 who participated in the Nurses’ Health Study and had no history of kidney stones, those who consumed an average of over 4,099 mg of potassium per day had a 35% lower risk of kidney stones over a 12-year follow-up period than those who averaged less than 2,407 mg of potassium per day 85).

Some research suggests that supplementation with potassium citrate reduces hypercalciuria as well as the risk of kidney stone formation and growth 86). In a clinical trial of 57 patients with at least two kidney stones (either calcium oxalate or calcium oxalate plus calcium phosphate) over the previous 2 years and hypocitraturia (low urinary citrate levels), supplementation with 30–60 mEq potassium citrate (providing 1,173 to 2,346 mg potassium) for 3 years significantly reduced kidney stone formation compared with placebo 87). This study was included in a 2015 Cochrane review of seven studies that examined the effects of potassium citrate, potassium-sodium citrate, and potassium-magnesium citrate supplementation on the prevention and treatment of calcium-containing kidney stones in a total of 477 participants, most of whom had calcium oxalate stones 88). The potassium citrate salts significantly reduced the risk of new stones and reduced stone size. However, the proposed mechanism involves citrate, not potassium per se; citrate forms complexes with urinary calcium and increases urine pH, inhibiting the formation of calcium oxalate crystals 89). The authors of a draft Agency for Healthcare Research and Quality report 90) concluded that observational studies suggest an association between higher potassium intakes and lower risk of kidney stones. However, they also found the evidence insufficient to determine whether potassium supplements are effective because only one trial that addressed this question 91) met their inclusion criteria.

Additional research is needed to fully understand the potential link between dietary and supplemental potassium and the risk of kidney stones.

Bone health

Observational studies suggest that increased consumption of potassium from fruits and vegetables is associated with increased bone mineral density 92). This evidence, combined with evidence from metabolic studies and a few clinical trials, suggests that dietary potassium may improve bone health.

The underlying mechanisms are unclear, but one hypothesis is that potassium helps protect bone through its effect on acid-base balance 93). Diets that are high in acid-forming foods, such as meats and cereal grains, contribute to metabolic acidosis and might have an adverse effect on bone. Alkaline components in the form of potassium salts (potassium bicarbonate or citrate, but not potassium chloride) from food or potassium supplements might counter this effect and help preserve bone tissue. In the Framingham Heart Study for example, higher potassium intake was associated with significantly greater bone mineral density in 628 elderly men and women 94). In another study, the DASH eating pattern significantly reduced biochemical markers of bone turnover 95). This eating pattern has a lower acid load than typical Western diets and is also high in calcium and magnesium, in addition to potassium, so any independent contribution of potassium cannot be determined.

Only a few clinical trials have examined the effects of potassium supplements on markers of bone health. One trial found that supplementation with potassium citrate at either 60 mmol/day (2,346 mg potassium) or 90 mmol/day (3,519 mg potassium) for 6 months significantly reduced urinary calcium excretion compared with placebo in 52 healthy men and women older than 55 years 96). In another clinical trial, 201 healthy adults aged 65 years or older received daily supplementation with 60 mEq potassium citrate (providing 2,346 mg potassium) or placebo as well as 500 mg/day calcium (as calcium carbonate) and 400 IU/day vitamin D3 for 2 years 97). Potassium supplementation significantly increased bone mineral density at the lumbar spine and bone microarchitecture compared with placebo. In a similar clinical trial among older adults, supplemental potassium bicarbonate (mean doses of 2,893 or 4,340 mg/day potassium) for 84 days significantly reduced biochemical markers of bone turnover and urinary calcium excretion 98). Conversely, a clinical trial in 276 postmenopausal women aged 55–65 years found that supplementation with potassium citrate at either 18.5 mEq/day (providing 723 mg potassium) or 55.5 mEq/day (2,170 mg potassium) for 2 years did not significantly reduce bone turnover or increase bone mineral density at the hip or lumbar spine compared with placebo 99).

Overall, higher intakes of potassium from diets that emphasize fruits and vegetables might improve bone health. However, more research is needed to elucidate the underlying mechanisms and tease out potassium’s individual contribution.

Blood glucose control and type 2 diabetes

Type 2 diabetes is a growing public health concern that currently affects almost 12% of U.S. adults 100). Although obesity is the primary risk factor for type 2 diabetes, other metabolic factors also play a role. Because potassium is needed for insulin secretion from pancreatic cells, hypokalemia impairs insulin secretion and could lead to glucose intolerance 101). This effect has been observed mainly with long-term use of diuretics (particularly those containing thiazides) or hyperaldosteronism (excessive aldosterone production), which both increase urinary potassium losses, but it can occur in healthy individuals as well 102).

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 103). These associations might be stronger in African Americans, who tend to have lower potassium intakes, than in whites 104). For example, one study of 1,066 adults aged 18–30 years without diabetes found that those with urinary potassium levels in the lowest quintile were more than twice as likely to develop type 2 diabetes over 15 years of follow-up than those in the highest quintile 105). Among 4,754 participants from the same study with potassium intake data, African Americans with lower potassium intakes had a significantly greater risk of type 2 diabetes over 20 years of follow-up than those with higher intakes, but this association was not found in whites.

In another observational study, which analyzed data from 84,360 women aged 34–59 years participating in the Nurses’ Health Study, those in the highest quintile of potassium intake had a 38% lower risk of developing type 2 diabetes over 6 years of follow-up than those in the lowest quintile 106). Serum potassium levels were inversely associated with fasting glucose levels in 5,415 participants aged 45–84 years from the Multi-Ethnic Study of Atherosclerosis, but these levels had no significant association with diabetes risk over 8 years of follow-up 107).

Although observational studies suggest that potassium status is linked to blood glucose control and type 2 diabetes, this association has not been adequately evaluated in clinical trials. In a small clinical trial in 29 African American adults with prediabetes and low to normal serum potassium levels (3.3–4.0 mmol/L), supplementation with 40 mEq (1,564 mg) potassium (as potassium chloride) for 3 months significantly lowered fasting glucose levels, but it did not affect glucose or insulin measures during an oral glucose tolerance test 108).

The findings from studies conducted to date are promising. But more research, including randomized controlled trials, is needed before potassium’s link with blood glucose control and type 2 diabetes can be confirmed.

High Potassium (Hyperkalemia)

In healthy people with normal kidney function, high dietary potassium intakes do not pose a health risk because the kidneys eliminate excess amounts in the urine 109). In addition, there is no evidence that high intakes of dietary potassium have adverse effects. Therefore, the Food and Nutrition Board did not set a Tolerable Upper Intake Level (UL) for potassium.

However, in people with impaired urinary potassium excretion due to chronic kidney disease or the use of certain medications, such as angiotensin converting enzyme (ACE) inhibitors or potassium-sparing diuretics, even dietary potassium intakes below the AI can cause hyperkalemia 110). Hyperkalemia can also occur in people with type 1 diabetes, congestive heart failure, adrenal insufficiency, or liver disease 111). Individuals at risk of hyperkalemia should consult a physician or registered dietitian about appropriate potassium intakes from all sources.

Although hyperkalemia can be asymptomatic, severe cases can cause muscle weakness, paralysis, heart palpitations, paresthesias (a burning or prickling sensation in the extremities), and cardiac arrhythmias that could be life threatening 112).

Hyperkalemia is the medical term that describes a potassium level in your blood that’s higher than normal 113). Potassium is a nutrient that is critical to the function of nerve and muscle cells, including those in your heart 114).

Your blood potassium level is normally 3.6 to 5.2 millimoles per liter (mmol/L) 115). Hyperkalemia is a potassium level of greater than 5.5. Patients with hyperkalemia may have a normal electrocardiogram or only subtle changes. Having a blood potassium level higher than 7.0 mmol/L can be dangerous and requires immediate treatment.

High potassium symptoms

There are often no symptoms with a high level of potassium.

High potassium is usually found when your doctor has ordered blood tests to help diagnose a condition you’re already experiencing or to monitor medications you’re taking. It’s usually not discovered by chance.

If you have symptoms of hyperkalemia, particularly if you have kidney disease or are taking medications that raise your potassium level, call your doctor immediately. Hyperkalemia is a serious and potentially life-threatening disorder. It can cause:

  • Muscle fatigue
  • Weakness
  • Paralysis
  • Abnormal heart rhythms (arrhythmias) – slow, weak, or irregular pulse
  • Nausea

Talk to your doctor about what your results mean. You may need to change a medication that’s affecting your potassium level, or you may need to treat another medical condition that’s causing your high potassium level 116). Treatment of high potassium is often directed at the underlying cause. In some instances, you may need emergency medications or dialysis.

If you have symptoms of hyperkalemia and have reason to think your potassium level might be high, call your doctor immediately.

Can hyperkalemia be prevented ?

Dietary changes can help prevent and treat high potassium levels. Talk to your doctor to understand any risk you might have for hyperkalemia. Your doctor may recommend foods that you may need to limit or avoid. These may include:

  • asparagus, avocados, potatoes, tomatoes or tomato sauce, winter squash, pumpkin, cooked spinach
  • oranges and orange juice, nectarines, kiwifruit, bananas, cantaloupe, honeydew, prunes and raisins or other dried fruit.

If you are on a low-salt diet, avoid taking salt substitutes 117).

Causes of Hyperkalemia (high potassium)

Often, a report of high blood potassium isn’t true hyperkalemia. Instead, it may be caused by the rupture of blood cells in the blood sample during or shortly after the blood draw. The ruptured cells leak their potassium into the sample. This falsely raises the amount of potassium in the blood sample, even though the potassium level in your body is actually normal. When this is suspected, a repeat blood sample is done.

The most common cause of genuinely high potassium (hyperkalemia) is related to your kidneys 118), such as:

  • Acute kidney failure
  • Chronic kidney disease

Other causes of hyperkalemia include:

  • Addison’s disease (adrenal failure)
  • Alcoholism or heavy drug use that causes rhabdomyolysis, a breakdown of muscle fibers that results in the release of potassium into the bloodstream
  • Angiotensin-converting enzyme (ACE) inhibitors
  • Angiotensin II receptor blockers (ARBs)
  • Destruction of red blood cells due to severe injury or burns
  • Excessive use of potassium supplements
  • Type 1 diabetes

ACE inhibitors and angiotensin receptor blockers (ARBs)

ACE inhibitors, such as benazepril (Lotensin®), and ARBs such as losartan (Cozaar®), are used to treat hypertension and heart failure, slow progression of kidney disease in patients with chronic kidney disease and type 2 diabetes, and decrease morbidity and mortality after myocardial infarction 119). These medications reduce urinary potassium excretion, which can lead to hyperkalemia. Experts recommend monitoring potassium status in people taking ACE inhibitors or ARBs, especially if they have other risk factors for hyperkalemia, such as impaired kidney function 120).

Potassium sparing diuretics

Potassium-sparing diuretics, such as amiloride (Midamor®) and spironolactone (Aldactone®), reduce the excretion of potassium in the urine and can cause hyperkalemia 121). Experts recommend monitoring potassium status in people taking these medications, especially if they have impaired kidney function or other risk factors for hyperkalemia 122).

Loop and thiazide diuretics

Treatment with loop diuretics, such as furosemide (Lasix®) and bumetanide (Bumex®), and thiazide diuretics, such as chlorothiazide (Diuril®) and metolazone (Zaroxolyn®), increases urinary potassium excretion and can lead to hypokalemia 123). Experts recommend monitoring potassium status in people taking these medications, and initiating potassium supplementation if warranted.

Exams and Tests

The health care provider will perform a physical exam and ask about your symptoms.

Tests that may be ordered include:

  • Electrocardiogram (ECG)
  • Potassium level

Your provider will likely check your blood potassium level and do kidney blood tests on a regular basis if you:

  • Have been prescribed extra potassium
  • Have chronic kidney disease
  • Take medicines to treat heart disease or high blood pressure
  • Use salt substitutes

Treatment of Hyperkalemia

If your potassium level is very high, or if there are dangerous indications such as changes in an electrocardiogram, emergency treatment is needed. That may involve supplying calcium to the body through an intravenous to treat the effects on muscles and the heart or administering glucose and insulin through an intravenous to decrease potassium levels long enough to correct the cause. There are also medicines that help remove the potassium from your intestines and in some cases, a diuretic may be given.

Emergency treatment may also include kidney dialysis if kidney function is deteriorating; medication to help remove potassium from the intestines before absorption; sodium bicarbonate if acidosis is the cause; and water pills, or diuretics.

A doctor may also advise stopping or reducing potassium supplements and stopping or changing the doses of certain medicines for heart disease and high blood pressure. Always follow your health provider’s instructions about taking or stopping medicines.

Emergency treatment may include:

  • Calcium given into your veins (IV) to treat the muscle and heart effects of high potassium levels
  • Glucose and insulin given into your veins (IV) to help lower potassium levels long enough to correct the cause
  • Kidney dialysis if your kidney function is poor
  • Medicines that help remove potassium from the intestines before it is absorbed
  • Sodium bicarbonate if the problem is caused by acidosis
  • Some water pills (diuretics)

Changes in your diet can help both prevent and treat high potassium levels. You may be asked to:

  • Limit or avoid asparagus, avocados, potatoes, tomatoes or tomato sauce, winter squash, pumpkin, and cooked spinach
  • Limit or avoid oranges and orange juice, nectarines, kiwifruit, raisins, or other dried fruit, bananas, cantaloupe, honeydew, prunes, and nectarines
  • Avoid taking salt substitutes if you are asked to eat a low-salt diet

Your provider may make the following changes to your medicines:

  • Reduce or stop potassium supplements
  • Stop or change the doses of medicines you are taking, such as ones for heart disease and high blood pressure
  • Take a certain type of water pill to reduce potassium and fluid levels if you have chronic kidney failure

Follow your provider’s directions when taking your medicines:

  • DO NOT stop or start taking medicines without first talking to your provider
  • Take your medicines on time
  • Tell your provider about any other medicines, vitamins, or supplements you are taking

For people with heart failure

There are some drugs that heart failure patients take that are associated with hyperkalemia. These are: diuretics, beta-blockers and angiotension converting enzyme inhibitors (ACE inhibitors). For patients with heart failure on these drugs, if any symptoms are experienced as above, you should tell your doctor to make sure that the symptoms are not related to hyperkalemia.

If your potassium level is too high, you may need to cut back on certain foods (see the table). These tips can also help:

  • Soak or boil vegetables and fruits to leach out some of the potassium.
  • Avoid foods that list potassium or K, KCl, or K+ — chemical symbols for potassium or related compounds — as ingredients on the label.
  • Stay away from salt substitutes. Many are high in potassium. Read the ingredient lists carefully and check with your doctor before using one of these preparations.
  • Avoid canned, salted, pickled, corned, spiced, or smoked meat and fish.
  • Avoid imitation meat products containing soy or vegetable protein.
  • Limit high-potassium fruits such as bananas, citrus fruits, and avocados.
  • Avoid baked potatoes and baked acorn and butternut squash.
  • Don’t use vegetables or meats prepared with sweet or salted sauces.
  • Avoid all types of peas and beans, which are naturally high in potassium.
Potassium levels in common foods (source 124))
High potassiumMedium potassiumLow potassiumNo potassium
Fruits and vegetablesArtichokes, avocados, bananas, broccoli, coconut, dried fruits, leafy greens, kiwis, nectarines, oranges, papayas, potatoes, prunes, spinach, tomatoes, winter squash, yamsApples, apricots, asparagus, carrots, cherries, corn, eggplant, peaches, pears, peppers, pineapple juice, radishesBlueberries, cauliflower, cucumbers, grapefruit, grapes, green beans, lettuce, strawberries
Meat and proteinDried beans and peas, imitation bacon bits, nuts, soy productsBeef, eggs, fish, peanut butter, poultry, pork, veal
DairyMilk, yogurtSour cream
Grains and processed foodsPlain bagel, plain pasta, oatmeal, white bread, white riceBran muffins and cereals, corn tortillas, whole-wheat breadFruit punches, jelly beans, nondairy topping, nondairy creamers

Low Potassium (Hypokalemia)

Insufficient potassium intakes can increase blood pressure, kidney stone risk, bone turnover, urinary calcium excretion, and salt sensitivity (meaning that changes in sodium intakes affect blood pressure to a greater than normal extent).

Normally, your blood potassium level is 3.6 to 5.2 millimoles per liter (mmol/L). Severe potassium deficiency can cause hypokalemia, (serum potassium level less than about 3.6 mmol/L). A very low potassium level (less than 2.5 mmol/L) can be life-threatening and requires urgent medical attention.

Low potassium (hypokalemia) refers to a lower than normal potassium level in your bloodstream. Potassium is a chemical (electrolyte) that is critical to the proper functioning of nerve and muscles cells, particularly heart muscle cells. Hypokalemia affects up to 21% of hospitalized patients, usually because of the use of diuretics and other medications, but it is rare among healthy people with normal kidney function.

Mild hypokalemia is characterized by constipation, fatigue, muscle weakness, and malaise 125). Moderate to severe hypokalemia (serum potassium level less than about 2.5 mmol/L) can cause polyuria (large volume of dilute urine); encephalopathy in patients with kidney disease; glucose intolerance; muscular paralysis; poor respiration; and cardiac arrhythmias, especially in individuals with underlying heart disease 126). Severe hypokalemia can be life threatening because of its effects on muscle contraction and, hence, cardiac function 127).

Hypokalemia is rarely caused by low dietary potassium intake alone, but it can result from diarrhea due to potassium losses in the stool. It can also result from vomiting, which produces metabolic alkalosis, leading to potassium losses in the kidneys. Hypokalemia can also be caused by refeeding syndrome (the metabolic response to initial refeeding after a starvation period) because of potassium’s movement into cells; laxative abuse; diuretic use; eating clay (a type of pica); heavy sweating; or dialysis 128).

Magnesium depletion can contribute to hypokalemia by increasing urinary potassium losses 129). It can also increase the risk of cardiac arrhythmias by decreasing intracellular potassium concentrations. More than 50% of individuals with clinically significant hypokalemia might have magnesium deficiency 130). In people with hypomagnesemia and hypokalemia, both should be treated concurrently 131).

Low potassium symptoms may include:

  • Weakness
  • Fatigue
  • Muscle cramps
  • Constipation
  • In severe cases, life-threatening paralysis may develop, such as with hypokalemic periodic paralysis.

Abnormal heart rhythms (arrhythmias) are the most worrisome complication of very low potassium levels, particularly in people with underlying heart disease.

In most cases, low potassium is found by a blood test that is done because of an illness, or because you are taking diuretics. It is rare for low potassium to cause isolated symptoms such as muscle cramps if you are feeling well in other respects.

Talk to your doctor about what your results mean. You may need to change a medication that’s affecting your potassium level, or you may need to treat another medical condition that’s causing your low potassium level.

Treatment of low potassium is directed at the underlying cause and may include potassium supplements. Don’t start taking potassium supplements without talking to your doctor first.

Causes of Hypokalemia (low potassium)

Low potassium (hypokalemia) has many causes. The most common cause is excessive potassium loss in urine due to prescription water or fluid pills (diuretics). Vomiting or diarrhea or both can result in excessive potassium loss from the digestive tract. Only rarely is low potassium caused by not getting enough potassium in your diet.

Causes of potassium loss leading to low potassium include:

  • Chronic kidney disease
  • Diabetic ketoacidosis
  • Diarrhea (causing anal irritation)
  • Excessive alcohol use
  • Excessive laxative use
  • Excessive sweating
  • Folic acid deficiency
  • Prescription water or fluid pills (diuretics) use
  • Primary aldosteronism
  • Vomiting
  • Some antibiotic use

Groups at Risk of Potassium Inadequacy

Potassium inadequacy can occur with intakes that are below the Adequate Intake (AI) [intake at this level is assumed to ensure nutritional adequacy; established when evidence is insufficient to develop an Recommended Dietary Allowance (RDA)] but above the amount required to prevent hypokalemia. The following groups are more likely than others to have poor potassium status.

People with inflammatory bowel diseases

Potassium is secreted within the colon, and this process is normally balanced by absorption 132). However, in inflammatory bowel disease (including Crohn’s disease and ulcerative colitis), potassium secretion increases, which can lead to poor potassium status. Inflammatory bowel diseases are also characterized by chronic diarrhea, which can further increase potassium excretion 133).

People who use certain medications, including diuretics and laxatives

Certain diuretics (e.g., thiazide diuretics) that are commonly used to treat high blood pressure increase urinary potassium excretion and can cause hypokalemia 134). Potassium- sparing diuretics, however, do not increase potassium excretion and can actually cause hyperkalemia. Large doses of laxatives and repeated use of enemas can also cause hypokalemia because they increase losses of potassium in stool.

People with pica

Pica is the persistent eating of non-nutritive substances, such as clay. When consumed, clay binds potassium in the gastrointestinal tract, which can increase potassium excretion and lead to hypokalemia 135). Cessation of pica combined with potassium supplementation can restore potassium status and resolve symptoms of potassium deficiency.

Hypokalemia Treatment

If your condition is mild, your provider will likely prescribe oral potassium pills. If your condition is severe, you may need to get potassium through a vein (IV).

If you need diuretics, your provider may:

  • Switch you to a form that keeps potassium in the body. This type of diuretic is called potassium-sparing.
  • Prescribe extra potassium for you to take every day.

Eating foods rich in potassium can help treat and prevent low level of potassium. These foods include:

  • Avocados
  • Baked potato
  • Bananas
  • Bran
  • Carrots
  • Cooked lean beef
  • Milk
  • Oranges
  • Peanut butter
  • Peas and beans
  • Salmon
  • Seaweed
  • Spinach
  • Tomatoes
  • Wheat germ

Outlook (Prognosis)

Taking potassium supplements can usually correct the problem. In severe cases, without proper treatment, a severe drop in potassium level can lead to serious heart rhythm problems that can be fatal.

References   [ + ]