Potassium

A severe potassium deficiency, hypokalaemia, is a serum potassium concentration of <3.5 mmol/L (2). Hypokalaemia causes cardiac arrhythmias, muscle weakness and glucose intolerance (2). More common is a moderate potassium deficiency without hypokalaemia, which is characterised by an increase in blood pressure, that may in turn, increase the risk of cardiovascular disease and stroke, an increase in salt sensitivity (defined as the response of the blood pressure to a lowered sodium intake or sodium loading), an increased risk of kidney stones and a loss in bone mineral density and an increased bone turnover due to loss of calcium in the urine, reduced bone formation and increased bone resorption (2-4).

Increased potassium intake in adults can benefit blood pressure without adversely affecting blood lipids, catecholamines or renal function (1). Increased potassium intakes might reduce blood pressure in children, though data are limited (1), and, an inverse relationship between potassium intake and risk of stroke has been suggested (1). Increasing daily potassium intakes from fruits and vegetables (alkaline foods, as opposed to meat and dairy produce, acid-forming foods) may help to reduce calcium excretion in the urine and thereby have a positive effect on bone mass and concomitant benefit on risk of osteoporosis (3). A large, longitudinal study reported that 24‐hour urinary potassium excretion was inversely associated with all‐cause mortality in a general population of Japanese adults aged 21 to 85 years (5).

Due to the interrelationship of potassium and sodium in the body, a one-to-one intake ratio of potassium to sodium is considered most beneficial for health (1, 6). Inadequate intakes of potassium may often be seen together with a high consumption of sodium, possibly due to dietary transitions towards a more processed diet.

Elevated potassium intakes are generally not harmful per se (1), the risk being restricted to patient groups with impaired urinary potassium excretion who may be at risk of hyperkalaemia if consumption increases (2). Other groups at risk are those with chronic kidney damage and certain medications, e.g. antihypertensives that block the renin-angiotensin system (angiotensin converting enzyme inhibitors or angiotensin receptor blockers) and some diuretics can cause high potassium levels if dietary intake is unchecked (3). Elderly patients with multiple morbidities and polypharmacy may be most at risk.

There is a relationship between over-consumption of sodium and under-consumption of potassium, both of which are important risk factors for cardiovascular disease and stroke. Recommendations to increase dietary potassium intakes may help to reduce this risk, and that of osteoporosis and kidney stones. Assessment of potassium status is not routinely done in clinical practice.

NIH potassium fact sheet