Potassium requirements can be affected by climate and physical activity, the use of diuretics, and the intake of other electrolytes, notably sodium
- potassium blunts the effect of sodium chloride on blood pressure, mitigating salt sensitivity and lowering urinary calcium excretion
- given this interrelatedness, requirement for potassium depends to some extent on dietary sodium, however, the ideal sodium:potassium intake ratio is not sufficiently established to use in setting requirements (1)
Guidance values for Adequate Intake of Potassium (1):
- Adequate Intake (AI) for adults has been defined as (1):
- female = 72 mmol/day
- male = 100 mmol/day
- AI in pregnancy
- potassium accretion in pregnancy is small, so the AI is set at the same level as that for adult females (72 mmol/day)
- AI in lactation
- lactation AI is set at that for adult females plus an allowance for potassium secreted in breast milk (82 mmol/day)
- 1 mmol potassium = 39 mg potassium
However these values will vary based on the factors described above.
According to NHS, adults (19 to 64 years) need 3,500mg of potassium a day, which can be obtained from daily diet (2).
Notes (1):
- potassium is the major cation of intracellular fluid and an almost constant component of lean body tissues
- a high intracellular concentration of potassium is maintained by the Na+/K+-ATPase pump. The movements of potassium out of cells and sodium into cells changes the electrical potential during depolarisation and repolarisation of nerve and muscle cells
- leafy green vegetables, vine fruit such as tomatoes, cucumbers, eggplant and pumpkin, and root vegetables are particularly good sources of potassium. It is also moderately abundant in beans and peas, tree fruits such as apples, oranges and bananas, milks and yoghurts and meats
- in unprocessed foods, potassium occurs mainly with bicarbonate-generators like citrate. Potassium added during processing is generally as potassium chloride. About 85% of potassium is absorbed.
- most of the ingested potassium (80-90%) is excreted in urine, the rest being excreted in faeces and sweat
- potassium filtered in the glomeruli of the kidney is mostly reabsorbed
- potassium in urine results from secretion into the cortical collecting duct under control of the hormone, aldosterone. High plasma levels of potassium stimulate release of aldosterone to increase the secretion of potassium.
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