Potassium in nutrition and human health
To maintain health, the diet of humans must contain potassium, in its ionic form (K+), in millimolar amounts. In 2004-2006, the Institute of Medicine of the National Academies of Science[1] and its Food and Nutrition Board[2] recommended that adult humans consume 4700 milligrams (mg) of potassium per day, which amounts to 120 millimoles (mmol) potassium per day, calculated from the atomic mass of potassium, 39.1 mg per mmol: 4700 mg/39.1 mg/mmol =120 mmol.
Humans must regularly consume potassium as the body does not store it (as it does iron and fat, say), and the kidney continues to excrete it in the urine even when potassium intake ceases. Potassium-rich foods include leafy green vegetables, vine fruits (e.g., squash, tomatoes, cucumbers, etc.), and tree fruits.
Potassium ranks as the most abundant cation (positive ion) inside animal cells (intracellular), and as such contributes critically in numerous important ways to the optimal functioning of cells and therefore to optimal functioning of the organ systems and individuals they compose. It plays a role in the synthesis of proteins and in the biochemical transformations required for carbohydrate metabolism.
The ratio of the concentrations of potassium in intracellular fluid (ICF) and in its surrounding interstitial extracellular fluid (ECF) has important effects of the rate of transmission of electrical activity (pulses) along the nerve fiber and skeletal muscle cells, and affects the degree of contraction of arteries and arterioles (vascular tone). As extracellular potassium varies in the 3-6 mmol/L range, while intracellular potassium concentrations averages about 145 mmol/L, small changes in extracellular potassium concentration have a greater effect on the ratio than small changes in intracellular potassium concentrations. This article discusses the implication changes in the ICF-to-ECF potassium concentration ratio in sections below.
In healthy persons, the amount of potassium consumed equals the amount excreted, largely by the kidney and gastrointestinal tract.
Disturbances relating to body potassium deficiency may result from:
- inadequate consumption of potassium-rich foods;
- inappropriate excretion in urine;
- inappropriate excretion of potassium in feces.
Disturbances relating to body potassium excess may result from:
- drugs and kidney diseases that impair the kidney’s ability to excrete potassium in urine;
- deficiency of hormones that act to promote kidney and gastrointestinal excretion of potassium.
Subsequent sections will elaborate on the above introductory concepts.
Requirements for Potassium Consumption by Humans
[...in progress...]
References
- ↑ Otten JJ, Hellwig JP, Meyers LD (editors) (2006) Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. National Academies Press. Pages 370-379. ISBN 0-309-65646-X
- ↑ Panel on Dietary Reference Intakes for Electrolytes and Water. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. Food and Nutrition Board. Institute of Medicine of The National Academies (2004) Dietary Reference Intakes For Water, Potassium, Sodium, Chloride, and Sulfate “Potassium” pp. 186-268. The National Academies Press, Washington, D.C.