Potassium — Food Sources, Daily Intake, Deficiency Symptoms

Absorption, Metabolism, and Regulation

Potassium is the most abundant positively charged ion in cellular fluid, and it is essential for maintaining normal cell function, particularly in muscle and nervous tissues.

In adults, the estimated total body potassium (K+) is around 46mmol/kg (about 1800mg/kg) for men and 39 mmol/kg (around 1500mg/kg) for women. Only a small portion of this, approximately 2%, is located in the extracellular fluid. Most potassium in the body is found within the intracellular space of skeletal muscle (1, 2, 3).

In healthy individuals, approximately 90% of dietary potassium is absorbed in the intestines, mainly through passive diffusion in the small intestine (3).

Normal serum potassium concentrations are kept in the range of 3.5 to 5.0 mmol/L. The body maintains this potassium balance by redistributing potassium inside and outside the cell, absorbing potassium in the gastrointestinal tract, and excreting it through the kidneys and intestines.

The redistribution of potassium is achieved through a pump found in almost all cell membranes called the sodium and potassium pump or Na+-K+-ATPase. This pump leads sodium ions into the cell and potassium ions out. This process leads to the formation of an electrical gradient used by neurons and muscles for nervous system function and muscle contraction (4). 

Around 90% of the potassium ingested is eliminated through the kidneys in urine, while approximately 10% is excreted through feces, with a minimal quantity lost through sweat (1).

The steroid hormone aldosterone, produced by the adrenal glands, is one of the main regulators of potassium in the body. It increases the elimination of potassium and reabsorption of sodium in the kidneys, thus increasing blood pressure.

Recommended Intakes 

Individual potassium needs may differ based on age, gender, physiological state, genetics, blood pressure status, and sodium intake. 

The table below presents the adequate daily potassium intake in mg, according to the Dietary Guidelines for Americans 2020-2025, based on age and gender (5).

The adequate intake of potassium for pregnant women above the age of 18 is 2900mg per day, while this value is 2800mg for lactating women (5).

Currently, blood pressure is the primary factor in determining potassium requirements. Studies indicate that individuals of African descent are more susceptible to hypertension and show greater responsiveness to potassium supplementation than individuals of European descent. Moreover, hypertensive individuals tend to benefit more from increased potassium intake than those with normal blood pressure, particularly if they consume a high-sodium diet (1).

Food Sources of Potassium

Typically, healthy adults get their dietary potassium primarily from vegetables, fruits, meats, and dairy products.

Some foods particularly rich in potassium include potatoes, tomatoes, beans, bananas, oranges, cantaloupes, black strap molasses, beef, turkey, and salmon (2).

The concentration of potassium tends to be greater in fruits and vegetables compared to cereals and meat.

The table below presents the potassium values of some foods rich in this mineral according to their average serving sizes.

Adding salt to foods and draining the liquid leads to an exchange of sodium (Na+) for potassium (K+), reducing the potassium content of foods. Processed foods typically have higher sodium and lower potassium content than fresh foods (1, 2).

You can also find a list of foods high in potassium based on 100g servings. These include tarragon, raw soybeans, sun-dried tomatoes, spices, and beans.

Health Benefits and Functions of Potassium

Potassium's health benefits are vast and essential for overall well-being. This section delves into its multifaceted functions, from regulating blood pressure to supporting kidney and muscle function.