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Sources and physiological effects

Dietary sources
Potassium is essential to all life forms, which is why it is widely found in unprocessed plant and animal foods. Plant-based foods are the primary sources used for meeting nutrient demands – above all vegetables and fruit, potatoes, whole grains, pulses and nuts. Animal foods, are comparatively lower in potassium, as are fats, oils, sugar, jams, starch flours and processed foods. As the element is water-soluble, potassium losses occur due to soaking, blanching and cooking in water (when the cooking water is discarded).
Physiological effects
Cell	As a sodium antagonist it is responsible for maintaining cell volume (osmosis) Excitability of nerve and muscle cells
Energy metabolism	Building up ATP and storing glycogen in the muscles
Cardiovascular system	Essential for stimulus formation, transmission and cardiac muscle contraction Maintaining normal blood pressure
Acid-base balance	Regulation of the acid-base balance by influencing acid excretion via the kidneys

EFSA Health Claims

Health Claims		EFSA Opinion
Potassium	Contributes to a normal function of the nervous system Contributes to normal muscle function Contributes to maintaining normal blood pressure	<

Recommended intake

D-A-CH reference values for the intake of potassium (Reference values EFSA and NHI )
	Age	Potassium (mg/d)
Infants (months)
	0-4	400
	4-12	650
Children (years)
	1-4	1100
	4-7	1300
	7-10	2000
	10-13	3600
	13-15	4000
Teenagers/adults (years)		Women	Men
	15-19	4000	4000
	19-25	4000	4000
	25-51	4000	4000
	51-65	4000	4000
	> 65	4000	4000
Pregnant women	N/A
Breast-feeding women	N/A
Increased need	Sports (sweat loss), low potassium (inadequate fruit/vegetables) and high salt diet, diarrhea, vomiting, frequent use of laxatives, Cushing's disease, kidney disease, magnesium deficiency
Special group at risk of deficiency	Competitive athletes, bulimia, diabetes mellitus, Cushing's syndrome, etc;
Note	The values for daily requirements vary greatly. For example, the Food and Nutrition Board/USA gives the following daily requirement (Adequate Intake (AI)): 4700 mg

Recommended intake according to food labelling regulations
(=100 % TB marking on label)		2000 mg/d
Safety of the nutrient
UL	Long-term daily intake at which no negative health effects are to be expected	3000 mg/d READ MORE
NOAEL	Maximum intake, with no observed adverse effect	N/A
Safety	EFSA has investigated the safety of potassium.

Detailed information

Physiological significance of potassium

Potassium is the most important cation of the intracellular space and contributes to the metabolic activity of every cell. The body store Fof potassium is about 2 g/kg body weight, 99% of the potassium content being intracellular (1). The intracellular potassium concentration is regulated via the membranous Na⁺⁺/K⁺-ATPase. The ratio of intracellular to extracellular potassium ions is influenced by hormones and pH. While insulin, aldosterone, catecholamines and a metabolic alkalosis increase potassium uptake into the cell, a metabolic acidosis leads to a potassium shift from intra- to extracellular in exchange for H⁺ ions (2). The high intracellular potassium content is essential for the bioelectricity of cell membranes and central for stimulus transmission and muscle contractions. Changes in the cellular potassium gradient are therefore mainly associated with – sometimes serious – neuromuscular dysfunctions. In addition to general states of exhaustion, muscle weakness and cramps, constipation, paresthesia and paralysis and cardiac arrhythmia can occur. In cell metabolism, potassium acts as an activator of numerous enzymes such as glycolysis enzymes. In addition, potassium is involved in protein synthesis and in the formation of high-energy phosphate compounds (ATP). Potassium also regulates fluid balance – by influencing the renal net acid excretion and the acid-base balance – and is important for maintaining normal blood pressure (1).

Interaction between potassium and magnesium

Potassium and magnesium interact at different levels, from gastrointestinal absorption, endogenous distribution between intra- and extracellular compartments and various cellular processes to renal excretion. Animal studies show that the combined intake of magnesium and potassium increases the absorption and retention of magnesium by 40% (4) (5). Conversely, magnesium improves cellular potassium utilization, since Na⁺/K⁺-ATPase is magnesium-dependent (1). In various diseases of renal, gastrointestinal and endocrinological nature, deficiency symptoms of the two intracellular cations occur together.

Potassium and magnesium deficiency increase risks of cardiovascular diseases

Drug-induced potassium and magnesium deficiencies (e.g. by diuretics, cardiac glycosides) are of great clinical importance in patients suffering from high blood pressure and/or heart failure. Undersupply can promote cardiac arrhythmias and reduce glucose tolerance. In addition, high potassium losses can lead to dangerous interactions with pharmaceuticals taken in parallel, such as cardiac glycosides and diuretics (6). Patients with cardiovascular diseases and angina pectoris generally benefit from potassium and magnesium supplements alongside medication. The arrhythmias caused by digitalis therapy can be reduced (1).

Potassium lowers blood pressure

Hypertensive patients can also benefit from potassium supplementation. A meta-analysis of 33 randomized controlled trials with a total sample of 2609 patients showed that the oral supplementation of potassium salts led to a significant reduction in systolic and diastolic blood pressure. Patients with high sodium intake benefited in particular (7). The diuretics used in drug therapy for hypertension also promote potassium loss. In hypertension, daily potassium doses of 2 to 5 g are used. Sodium and potassium are closely linked. Animal studies have shown that an increase in blood pressure can be reduced by a low-salt diet and the additional administration of potassium (8).

Potassium deficiency in competitive sports

An undersupply of potassium leads to exhaustion, muscular weakness and cramps. Since potassium is stored in the muscle together with glycogen, it is particularly needed for replenishing the glycogen stores during the regeneration phase. During physical exertion, a potassium shift from intra- to extracellular occurs through glycogen degradation, and the potassium level in the blood rises. Therefore, a high potassium intake should be avoided during stress phases. To compensate for sweat loss, endurance athletes are recommended to take 150 to 300 mg potassium per liter of sports drink while exercising (3).

Drugs can lead to loss of potassium

The potassium balance is affected by a number of pharmaceuticals. The following drugs affect the potassium balance and may increase the risk of hypokalemia: aminoglycosides, beta-blockers, mineralocorticoids, theophylline, neomycin, penicillins, carbenoxolone, cisplatin, glucocorticoids, laxatives and non-potassium-saving diuretics (thiazides, loop diuretics) (1).

Reference values

Parameter	Substrate	Reference values	Description
Potassium	Serum	3,6 - 5,0 mmol/l	Potassium determination in serum only of limited importance, as 90 % of potassium is found intracellularly.
	Whole blood	43,5 - 48,7 mmol/l	Potassium is 90 % erythrocytically bound. Hematocrit-correlated whole blood analysis enables the correct interpretation of the supply congestion.
Interpretation
Low values		Potassium deficiency (associated magnesium deficiency) Often in diarrhea and vomiting as well as misuse of laxatives and diuretics
High values		Acute or chronic kidney failure, Addison's disease, potassium release through massive cell decay, e.g. in large-area burns, surgical interventions
Note on the measurement results
Hemolysis leads to a massive falsification of potassium levels in the plasma. The use of anticoagulants containing potassium, e.g. K-EDTA, also leads to incorrect results in both plasma and whole blood.

Deficiency symptoms

Impact on	Symptoms
General condition	Fatigue, fatigue, muscle weakness, muscle cramps
Cardiovascular system	Hypertension, arrhythmias, extrasystoles
Digestion	Constipation
Metabolism	Latent acidosis Decreased glucose tolerance Decreased insulin sensitivity

Indications

Effect	Indication	Dosage
Physiological Effects at a low intake	General health and prevention	200 - 400 mg/d
	Therapeutic suuport o balance the electrolytes when taking certain pharmaceuticals (e.g. diuretics, laxatives or cardiac drugs) for a long period of time	200 - 400 mg/d
	Supportive theraoy for cardiovascular disorders, cardiac arrhythmia and hypertension	200 - 400 mg/d




Pharmacological effects at a high intake	To treat a diagnosed potassium deficiency and in cases of increased demand such as in competitive sports.	400 - 1000 mg/d

Administration

General mode of administration
When	Due to possible interactions with food components, potassium should be taken outside of meal times. At high doses and in people who tolerate potassium poorly, it should be taken with meals for better digestive tolerance.
Side effects
In high doses, gastrointestinal complaints (nausea, vomiting, diarrhea and heartburn) can occur.
Contraindications
Dehydration, impaired kidney function, Addison's disease CAVE: ACE inhibitors, AT₂-receptor antagonists, cardiac glycosides, potassium-saving diuretics

Interactions

Drug interactions
ACE inhibitors	Increase in potassium levels by reducing excretion (especially in cases of reduced renal function).
AT₂-receptor antagonists	Increase in potassium levels (uncontrolled potassium intake should be avoided).
Cardiac glycosides (e.g. digitoxin)	High potassium levels weaken the effect of cardiac glycosides. Low potassium levels can lead to cardiac arrhythmia and increase the effect and toxicity of cardiac glycosides.
Thiazides, loop diuretics	Leads to a large loss of magnesium and, secondarily, to potassium deficiency.
Potassium-saving diuretics	Simultaneous intake of potassium leads to an increase in potassium blood levels.
NSAIDs (e.g. ibuprofen)	Increase in potassium blood levels. Potassium levels should be checked during long-term use.
Corticoids (e.g. hydrocortisone)	Decline in potassium levels. Narrow-meshed potassium control is necessary for long-term administration.
Nutrient interactions
Trace elements	High potassium intake reduces calcium excretion. Potassium and magnesium support each other in their effects. Excessive sodium intake can lead to potassium depletion in the long term and vice versa.

Description and related substances

Description

Mineral nutrients

Related substances

potassium bicarbonate, potassium carbonate, potassium chloride, potassium citrate, potassium gluconate, potassium glycerophosphate, potassium lactate, potassium hydroxide, potassium salts of orthophosphoric acid

References

1) Gröber, U. 2011. Mikronährstoffe. Metabolic Tuning – Prävention – Therapie. Wissenschaftliche Verlagsgesellschaft Stuttgart.
2) Gröber, U. 2008. Orthomolekulare Medizin. Ein Leitfaden für Apotheker und Ärzte.
3) Hahn, A. et al. 2006. Ernährung. Physiologische Grundlagen, Prävention und Therapie.
4) Markt, W. 2003. Physiologie der Interaktion zwischen Kalium und Magnesium. Journal für Mineralstoffwechsel. 10 (Sonderheft 1), 5-7.
5) Ryan, M. P. 1993. Interrelationship of magnesium and potassium homeostasis. Miner Elcetrolyte Metab. 19:290-5.
6) Piskernik, H. 2011. Elektrolyt-Verarmung durch Laxantien und Diuretika. März inside.
7) Whelton, P. K et al. 1997. Effects of oral potassium on blood pressure: Meta-Analysis of randomized controlled clinical trials. JAMA. 277(20):1624-1632.
8) Tobian, L. 1997. Dietary sodium chloride and potassium have effects on the pathophysiology of hypertension in humans and animals. Am J Clin Nutr. 65(2 Suppl):606S-611S.

References Interactions
Stargrove, M. B. et al. Herb, Nutrient and Drug Interactions: Clinical Implications and Therapeutic Strategies, 1. Auflage. St. Louis, Missouri: Elsevier Health Sciences, 2008.
Gröber, U. Mikronährstoffe: Metabolic Tuning –Prävention –Therapie, 3.
Auflage. Stuttgart: WVG Wissenschaftliche Verlagsgesellschaft Stuttgart, 2011.
Gröber, U. Arzneimittel und Mikronährstoffe: Medikationsorientierte Supplementierung, 3. aktualisierte und erweiterte Auflage. Stuttgart: WVG Wissenschaftliche Verlagsgesellschaft Stuttgart, 2014.