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.
Normal serum concentrations of potassium range from about 3.6 to 5.0 mmol/L and are regulated by a variety of mechanisms. Diarrhoea, vomiting, kidney disease, use of certain medications, and other conditions that alter potassium excretion or cause transcellular potassium shifts can cause hypokalaemia (serum levels below 3.6 mmol/L) or hyperkalaemia (serum levels above 5.0 mmol/L). Otherwise, in healthy individuals with normal kidney function, abnormally low or high blood levels of potassium are rare.
WHAT FOODS PROVIDE POTASSIUM?
Potassium is found in many foods. Most patients can get recommended amounts of potassium by eating a variety of foods, including the following:
- Fruits, such as dried apricots, prunes, raisins, orange juice, and bananas.
- Vegetables, such as acorn squash, potatoes, spinach, tomatoes, and broccoli.
- Lentils, kidney beans, soybeans, and nuts.
- Milk and yogurt.
- Meats, poultry, and fish.
Potassium is an ingredient in many salt substitutes that people use to replace table salt. Patients with kidney disease or on certain medications must be warned that these products could make their potassium levels too high.
WHAT KINDS OF POTASSIUM DIETARY SUPPLEMENTS ARE AVAILABLE?
Potassium is found in many multivitamin/multimineral supplements and in supplements that contain only potassium. Potassium in supplements comes in many different forms— a common form is potassium chloride, but other forms used in supplements are potassium citrate, potassium phosphate, potassium aspartate, potassium bicarbonate, and potassium gluconate. Research has not shown that any form of potassium is better than the others.
WHAT HAPPENS IF PATIENTS DON’T GET ENOUGH POTASSIUM?
Getting too little potassium can increase blood pressure, deplete calcium in bones, and increase the risk of kidney stones. Prolonged diarrhoea or vomiting, laxative abuse, diuretic use, eating clay, heavy sweating, dialysis, or using certain medications can cause severe potassium deficiency – hypokalaemia.
Symptoms of hypokalaemia include constipation, tiredness, muscle weakness, and not feeling well. More severe hypokalaemia can cause increased urination, decreased brain function, high blood sugar levels, muscle paralysis, difficulty breathing, and irregular heartbeat. Severe hypokalaemia can be life threatening.
SOURCE: National Institutes of Health