Potassium — Food Sources, Daily Intake, Deficiency Symptoms

Blood Pressure and Cardiovascular Health

Numerous studies suggest that insufficient potassium intake raises the risk of hypertension, particularly when accompanied by high sodium consumption. Conversely, higher potassium intake levels have been linked to lowered blood pressure, partially attributed to enhanced widening of blood vessels and increased sodium excretion through urine, leading to reduced plasma volume (3).

The Dietary Approaches to Stop Hypertension or DASH diet focuses on vegetables, fruits, and whole grains, which are low in saturated fats and sodium and high in potassium, calcium, magnesium, protein, and fiber (6).

A systematic review of 171 studies concluded that increasing potassium consumption, lowering sodium intake, and integrating potassium-enriched salt substitutes into the diet notably reduce blood pressure levels, especially in individuals with hypertension (7).

Potassium also decreases the risk of stroke. A 12-year longitudinal study revealed that for every additional 10 mmol of potassium consumed daily, there was a significant 40% decrease in mortality linked to strokes (8).

Another study found that for every 1000mg of potassium consumed, the risk of cardiovascular disease decreased by 18% (9).

Kidney Stones

Inadequate potassium intake impedes calcium reabsorption in the kidneys, leading to higher levels of urinary calcium excretion, which may result in hypercalciuria (too much calcium in the urine) and the formation of kidney stones (3).

Among a group of 45,619 men aged between 40 and 75 years with no prior history of kidney stones, individuals with the highest potassium intakes (over 4mg/day) exhibited a 51% reduced risk of developing kidney stones over a 4-year follow-up period compared to those with the lowest intakes (less than 2,9mg/day) (10).

Another study found that individuals with a history of kidney stones who increased their potassium intake via potassium citrate supplements notably decreased the likelihood of recurring stones, provided they concurrently increased their fluid intake (11).

Bone Health

A hypothesis known as the "acid-base balance" or "acid-alkaline theory" suggests that a diet with a high acid load (increased meat consumption and inadequate intake of fruits and vegetables) might contribute to bone loss. This theory proposes that the components of animal proteins and grains rich in phosphorus and sulfates generate acidity within the body. This may lead to calcium loss from the bones, which neutralizes the acid and increases acid and calcium excretion through the kidneys (9).

Potassium-rich foods have the potential to provide an "alkalinizing" effect because they contain compounds that can be metabolized to bicarbonate. Bicarbonate helps neutralize acids in the body, potentially protecting bone health. Observational studies have indicated that a diet high in potassium from fruits and vegetables is linked with increased bone density (9).

In a clinical trial involving 201 healthy adults aged 65 or older, participants received daily potassium citrate supplementation, providing over 2,3mg of potassium for 2 years. The results showed that potassium supplementation led to a significant increase in bone mineral density at the lumbar spine and improved bone microarchitecture compared to a placebo (12).

Similarly, in another clinical trial among older adults, supplemental potassium bicarbonate, with mean doses ranging from 2,9 to 4,3mg/day potassium, was administered for 84 days. This supplementation significantly reduced biochemical markers associated with bone turnover and decreased urinary calcium excretion (13).

However, another study found no significant association between potassium supplementation and bone turnover (3). 

Type 2 Diabetes

Several observational studies involving adults have identified associations between lower potassium intake or lower levels of serum or urinary potassium and higher rates of fasting glucose, insulin resistance, and the development of type 2 diabetes (3).

Hypokalemia, characterized by low potassium levels in the blood, can impair insulin secretion from pancreatic cells, potentially leading to glucose intolerance. This effect is often associated with long-term use of diuretics, especially those containing thiazides, or hyperaldosteronism, a condition marked by excessive aldosterone production, both of which increase urinary potassium losses. However, hypokalemia-induced impairment of insulin secretion can also occur in otherwise healthy individuals (3, 14).

Causes

Hypokalemia is commonly associated with medical conditions such as heart disease, kidney failure, malnutrition, and shock. Additionally, hypothermia and conditions involving increased blood cell production, such as leukemia, can also contribute to the development of hypokalemia. 

Certain subsets of patients are particularly susceptible to hypokalemia. For example, psychiatric patients undergoing drug therapy may be at increased risk of developing hypokalemia as a side effect of their medications (16).

Hypokalemia is seldom solely caused by inadequate dietary potassium intake; however, it can occur due to conditions such as diarrhea, where there is a significant potassium loss through stool. Vomiting can also contribute to hypokalemia by inducing metabolic alkalosis, which in turn leads to potassium losses through the kidneys (3).

Low potassium levels can result from impaired absorption, diuretic use, dialysis, and profuse sweating. Thus, people with inflammatory bowel disease (Crohn’s disease and ulcerative colitis) and people on certain medications, such as diuretics and laxatives, are at risk of potassium deficiency (3). 

As mentioned above, increased levels of aldosterone, called hyperaldosteronism, also cause hypokalemia.

Another cause of potassium deficiency is eating clay during a condition called pica. Pica is characterized by persistent and compulsive cravings for non-food items that lack nutritional value. Clay binds to potassium in the gastrointestinal system, inducing potassium excretion.

Symptoms

Clinical symptoms of hypokalemia typically do not become evident until the serum potassium level falls below 3 mmol/L. The severity of these symptoms tends to correlate with the degree and duration of hypokalemia (16). 

Manifestations of hypokalemia primarily affect the musculoskeletal and cardiovascular systems, such as muscle weakness or cramps, fatigue, heart arrhythmias, and palpitations.

The muscle weakness affects the lower limbs first, ascending to the trunk and upper extremities later. Weakness of gastrointestinal muscles leads to nausea, vomiting, and bloating (16).

Low potassium levels cause kidney changes, leading to frequent urination and extensive thirst.

Hypokalemia can indeed lead to glucose intolerance by impairing insulin secretion.

Due to similar causes, low potassium levels often occur along with low magnesium levels.

Causes

Increased potassium levels can result from increased potassium intake, decreased potassium excretion, or potassium storage changes in the body. 

One study showed that fewer than 3% of the population had typical intakes surpassing the recommended potassium allowance (15).

Hyperkalemia causes include infection, dehydration, kidney disease, diabetes, chemotherapy, significant trauma, crush injuries, or muscle pain, indicating rhabdomyolysis (17).

Additionally, certain medications, such as digoxin, potassium-sparing diuretics, non-steroidal anti-inflammatory drugs (NSAIDs), ACE inhibitors, recent IV potassium administration, total parenteral nutrition, potassium penicillin, and succinylcholine, can increase the risk of hyperkalemia (17).

Symptoms

People with chronic hyperkalemia may remain asymptomatic even at increased potassium levels, as their bodies may adapt to the higher potassium levels over time. 

On the other hand, individuals experiencing dramatic and acute shifts in potassium levels may develop severe symptoms even at lower levels. The severity of symptoms can vary depending on factors such as the rate of potassium level change, underlying health conditions, and individual tolerance levels.

Symptoms usually include muscle weakness, fatigue, heart palpitations, arrhythmias, and loss of consciousness (17).

Severe cases of untreated hyperkalemia can lead to heart failure and death.