Potassium is an essential nutrient involved in fluid, acid and electrolyte balance and is required for normal cellular function. Dietary deficiency of potassium is very uncommon due to the widespread occurrence of potassium in foods. Available evidence suggests that potassium can modulate blood pressure and increasing dietary potassium intake is associated with lower blood pressure.
Gastrointestinal symptoms (discomfort, mucosal lesions and sometimes ulceration) have been seen in healthy subjects taking some forms of potassium supplements (e.g. slow-release, wax matrix formulations) with doses ranging from about 1 to 5 g potassium per day, or more, but incidence and severity seem to be more dependent on the formulation than on dose. In healthy adults administration of single doses of 5-7 g potassium or more (as chloride or bicarbonate solutions) have been reported to cause elevated plasma potassium, adverse changes in heart function and peripheral nerve symptoms in a limited number of case reports.
In subjects with impaired kidney function and reduced urinary potassium excretion, elevated plasma potassium with adverse effects on heart function have been reported with intakes of potassium in the form of supplements or sodium-reduced salts equivalent to 1 g potassium per day or more in addition to food.
The available data are insufficient to establish a safe upper intake level for potassium.
Based on estimates of current potassium intakes in European countries, the risk of adverse effects from potassium intake from food sources (up to 5-6 g/day in adults) is considered to be low for the generally healthy population. Long-term intakes of about 3 g potassium per day as potassium chloride supplements, in addition to intake from foods, have been shown not to cause adverse effects (elevated plasma potassium or gastrointestinal symptoms) in healthy adults. However, a few case studies have reported that supplemental potassium in doses of 5-7 g/day can cause adverse effects on heart function in apparently healthy adults. In addition, gastrointestinal symptoms have been seen in healthy subjects taking some forms of potassium supplements with doses ranging from about 1 to 5 g potassium per day.
Certain groups, particularly those with impaired kidney excretion of potassium, are sensitive to adverse effects of increasing potassium intake on heart function associated with increases in plasma potassium. These include subjects engaging in strenuous activities leading to dehydration, with diabetes mellitus, with impaired kidney function, on cardiovascular disease drug treatment or other metabolic disorders affecting potassium balance. Elderly people may be more vulnerable to adverse effects of potassium due to reduced kidney function or due to use of drugs affecting potassium balance.