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). 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. In addition to maintaining cellular tonicity, this gradient is required for proper nerve transmission, muscle contraction, and kidney function.
Potassium is absorbed via passive diffusion, primarily in the small intestine. About 90% of ingested potassium is absorbed and used to maintain its normal intracellular and extracellular concentrations. Potassium is excreted primarily in the urine, some are 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. 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. This, combined with other obligatory losses, suggests that potassium balance cannot be achieved with intakes less than about 400–800 mg/day.
Deficiency Symptoms and Potassium Deficiency Symptoms
Certain conditions can cause potassium deficiencies or hypokalemia. These include:
- Malaise and fatigue
- Weakness and muscle pain all over the body
- Severe muscle weakness and paralysis
- Respiratory failure
- Painful obstructions in the gut
- Tingling, crawling, numb, or itchy sensations main felt in the hands, feet, legs, or arms
- Intermittent muscle spasms
- Kidney disease
- Overuse of diuretics
- Excess sweating, diarrhea, and vomiting
- Magnesium deficiency
- Use of antibiotics, such as carbenicillin and penicillin
- extreme fatigue
- Muscle spasms, weakness, or cramping
- Irregular heartbeat
- Constipation, nausea, or vomiting
Recommended Intakes for Potassium Deficiency Symptoms
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 (FNB) at the National Academies of Sciences, Engineering, and Medicine. 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, including
- 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 FNB 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. Table 1 lists the current AIs for potassium for healthy individuals. The FNB is reevaluating the DRIs for potassium and expects to release a new report with its findings in 2019.
|Birth to 6 months||400 mg||400 mg|
|7–12 months||700 mg||700 mg|
|1–3 years||3,000 mg||3,000 mg|
|4–8 years||3,800 mg||3,800 mg|
|9–13 years||4,500 mg||4,500 mg|
|14–18 years||4,700 mg||4,700 mg||4,700 mg||5,100 mg|
|19–50 years||4,700 mg||4,700 mg||4,700 mg||5,100 mg|
|51+ years||4,700 mg||4,700 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.
Food Source and Potassium Deficiency Symptoms
|Apricots, dried, ½ cup||1,101||31|
|Lentils, cooked, 1 cup||731||21|
|Prunes, dried, ½ cup||699||20|
|Squash, acorn, mashed, 1 cup||644||18|
|Raisins, ½ cup||618||18|
|Potato, baked, flesh only, 1 medium||610||17|
|Kidney beans, canned, 1 cup||607||17|
|Orange juice, 1 cup||496||14|
|Soybeans, mature seeds, boiled, ½ cup||443||13|
|Banana, 1 medium||422||12|
|Milk, 1%, 1 cup||366||10|
|Spinach, raw, 2 cups||334||10|
|Chicken breast, boneless, grilled, 3 ounces||332||9|
|Yogurt, fruit variety, nonfat, 6 ounces||330||9|
|Salmon, Atlantic, farmed, cooked, 3 ounces||326||9|
|Beef, top sirloin, grilled, 3 ounces||315||9|
|Molasses, 1 tablespoon||308||9|
|Tomato, raw, 1 medium||292||8|
|Soymilk, 1 cup||287||8|
|Yogurt, Greek, plain, nonfat, 6 ounces||240||7|
|Broccoli, cooked, chopped, ½ cup||229||7|
|Cantaloupe, cubed, ½ cup||214||6|
|Turkey breast, roasted, 3 ounces||212||6|
|Asparagus, cooked, ½ cup||202||6|
|Apple, with skin, 1 medium||195||6|
|Cashew nuts, 1 ounce||187||5|
|Rice, brown, medium-grain, cooked, 1 cup||154||4|
|Tuna, light, canned in water, drained, 3 ounces||153||4|
|Coffee, brewed, 1 cup||116||3|
|Lettuce, iceberg, shredded, 1 cup||102||3|
|Peanut butter, 1 tablespoon||90||3|
|Tea, black, brewed, 1 cup||88||3|
|Flaxseed, whole, 1 tablespoon||84||2|
|Bread, whole-wheat, 1 slice||81||2|
|Egg, 1 large||69||2|
|Rice, white, medium-grain, cooked, 1 cup||54||2|
|Bread, white, 1 slice||37||1|
|Cheese, mozzarella, part skim, 1½ ounces||36||1|
|Oil (olive, corn, canola, or soybean), 1 tablespoon|
*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. The updated labels and DVs must appear on food products and dietary supplements beginning in January 2020, but they can be used now. Foods providing 20% or more of the DV are considered to be high sources of a nutrient.
The U.S. Department of Agriculture’s Nutrient Database website lists the nutrient content of many foods and provides a comprehensive list of foods containing potassium ordered by food name and by nutrient content. The 2015–2020 Dietary Guidelines for Americans provides a list of foods with at least 5% of the DV for potassium per serving.
Health Benefit of Potassium
- Low levels of potassium in the blood (hypokalemia) – Taking potassium by mouth or intravenously (by IV) prevents and treats low levels of potassium in the blood.
- High blood pressure – Most research shows that taking potassium can lower blood pressure. Potassium seems to work best for people with high blood pressure, low potassium levels, high sodium intake, and for African Americans. People with high blood pressure should aim to eat foods that provide 3500-5000 mg of potassium daily. This intake of potassium is expected to lower blood pressure by about 4-5 mmHg in people with high blood pressure.
- Stroke – Higher intake of potassium from food has been linked with up to a 20% reduced risk of stroke. Taking potassium supplements have also been linked to a reduced risk of stroke. Higher quality research is needed to confirm this association.
Insufficient Evidence for
- Dental pain. Some research shows that using a toothpaste that contains potassium nitrite reduces tooth sensitivity. However, this toothpaste might still be less effective than other standard toothpaste.
- Alzheimer’s disease.
- Blurred vision.
- Chronic fatigue syndrome.
- Fatigue and mood swings in early menopause.
- Heart attack.
- Infant Colic.
- Insulin resistance.
- Ménière’s disease.
- Menopausal symptoms.
- Muscle weakness.
- Muscular dystrophy.
- Myasthenia gravis.
- Skin problems.
- Trouble sleeping (insomnia).