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Potassium

POTASSIUM

Potassium is one of the primary macrominerals in the body. It is a cation (a positively charged ion). The chemical symbol of potassium is K. Potassium is one of the primary minerals in nature. It is essential to both animals and plants.
The human body contains more than 100 grams of potassium. It is an important electrolyte in the cells and the primary positive cation inside them. This means that potassium maintains, for example, the action potential of neurons, used to pass on nerve impulses. Conversely, the major cation outside the cells is sodium (Na+). Potassium is also required for normal protein synthesis in the muscles.


The sodium-potassium-ATPase pump regulates the transfer of potassium and sodium through the cell membranes, which uses an ATP molecule to move three Na+ ions out of the cells and two K+ ions into the cells. This maintains the action potential of the cell membranes. It is estimated that the function of these cell membrane pumps makes up 20–40 % of the resting energy expenditure of an adult human. These pumps regulate, for example, the passage of nerve impulses, muscle contractions, and electrical heart functions. In addition to the abovementioned functions, potassium is required as a cofactor in carbohydrate metabolism pyruvate kinase.


The kidneys are an important part of potassium metabolism, also linked to sodium metabolism. The kidney glomeruli filter approximately 180 liters of blood plasma daily, containing 600 g sodium and 33 g potassium. If the kidneys' filtration process does not function properly, or if the potassium intake from food is insufficient, a potentially dangerous condition called hypokalemia may develop. If left untreated, it can lead to death.


Predisposing conditions for hypokalemia include:

  • Severe vomiting and diarrhea (potassium loss)
  • Excessive laxative use
  • Severe magnesium deficiency
  • Heart failure
  • Alcoholism
  • Continuous use of thiazide diuretics or furosemide
  • Anorexia or bulimia
  • Long-term consumption of large amounts of licorice

Hypokalemia symptoms include:

  • Fatigue and exhaustion
  • Muscular weakness and cramps
  • Intestinal paralysis
  • Heart palpitations
  • Muscular paralysis (in extreme cases)

According to epidemiological studies, increased potassium intake from food is linked to a lowered stroke risk. This is particularly true of individuals whose potassium intake from food was previously relatively low and who increased the number of fruits and vegetables in their diet. Sufficient potassium (and magnesium) intake has also been linked to improved bone density, particularly in women and elderly men. Foods containing potassium are generally also rich in bicarbonate, which acts as a pH buffer in the body. Sufficient bicarbonate intake helps balance bone metabolism.


Potassium intake has also been found to positively affect blood pressure; high potassium intake from food is linked to lower blood pressure compared to significantly lower potassium intake. A daily potassium intake of approximately 4,100 mg was linked to, on average, 2.8/1.1 mmHg (systolic/diastolic) lower blood pressure levels in healthy individuals, and up to 7.2/2.8 mmHg (systolic/ diastolic) lower blood pressure levels in individuals with hypertension whose potassium intake from food was only 1,700 mg/day.


Potassium supplements may also significantly lower blood pressure levels (-3.11/1.97 mmHg), but a medical expert should approve and monitor any such use.


The use of potassium supplements can have side effects in some cases. These include:

  • Nausea and vomiting
  • Intestinal discomfort
  • Diarrhea

HYPERKALEMIA (ELEVATED POTASSIUM LEVELS IN BLOOD)

Hyperkalemia means excessive potassium intake. This is not likely in terms of potassium from food, but when potassium is taken as a supplement, hyperkalemia is possible although unlikely. However, a Finnish Duodecim review (2018) states: “The potassium levels in the blood of a healthy individual cannot become excessive even if potassium-rich food or potassium tablets are digested. The excess potassium is excreted into the urine by the kidneys.”


On the other hand, it has been found that single doses of potassium supplements over 18 g can cause severe hyperkalemia. In Finland, the maximum recommended potassium supplement dose is 3.5 grams. In the US, the maximum recommended dose is 3,400 mg.


“A mild increase in blood potassium levels does not cause symptoms. At levels exceeding 5.5 nmol/L, increasing symptoms include fatigue, muscle weakness, various limb sensations, and severe paralytic symptoms. High potassium levels cause disorders of the cardiac function, detectable with an ECG.”


The cause behind hyperkalemia must always be investigated and appropriate hospital treatment sought. Many types of medication can cause hyperkalemia (including hypertension drugs containing potassium, ACE inhibitors, anti-inflammatory drugs, some antibiotics such as Trimethoprim-Sulfa, heparin, digitalis, beta and alpha-blockers and angiotensin receptor blockers).