Potassium in biology

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The Sodium–potassium pump a critical enzyme for regulating Sodium and Potassium levels in cells

intracellular ion for all types of cells, while having a major role in maintenance of fluid and electrolyte balance.[1][2] Potassium is necessary for the function of all living cells, and is thus present in all plant and animal tissues. It is found in especially high concentrations within plant cells, and in a mixed diet, it is most highly concentrated in fruits. The high concentration of potassium in plants, associated with comparatively very low amounts of sodium there, historically resulted in potassium first being isolated from the ashes of plants (potash
), which in turn gave the element its modern name. The high concentration of potassium in plants means that heavy crop production rapidly depletes soils of potassium, and agricultural fertilizers consume 93% of the potassium chemical production of the modern world economy.

The functions of potassium and sodium in living organisms are quite different. Animals, in particular, employ sodium and potassium differentially to generate electrical potentials in animal cells, especially in nervous tissue. Potassium depletion in animals, including humans, results in various neurological dysfunctions. Characteristic concentrations of potassium in model organisms are: 30–300mM in E. coli, 300mM in budding yeast, 100mM in mammalian cell and 4mM in blood plasma.[3]

Function in plants

See also:
source organs, and maintenance of cation:anion balance in the cytosol and vacuole.[5]

Function in animals

Potassium is the major

inwardly rectifying channels,[17][18][19][20][21] from prokaryotes and eukaryotes. The cell membrane potential created by potassium and sodium ions allows the cell to generate an action potential—a "spike" of electrical discharge. The ability of cells to produce electrical discharge is critical for body functions such as neurotransmission, muscle contraction, and heart function.[22]

Dietary recommendations

The U.S.

Adequate Intakes
(AIs) for when there is not sufficient information to set EARs and RDAs.

For both males and females under 9 years of age, the AIs for potassium are: 400 mg of potassium for 0 to 6-month-old infants, 860 mg of potassium for 7 to 12-month-old infants, 2,000 mg of potassium for 1 to 3-year-old children, and 2,300 mg of potassium for 4 to 8-year-old children.

For males 9 years of age and older, the AIs for potassium are: 2,500 mg of potassium for 9 to 13-year-old males, 3,000 mg of potassium for 14 to 18-year-old males, and 3,400 mg for males that are 19 years of age and older.

For females 9 years of age and older, the AIs for potassium are: 2,300 mg of potassium for 9 to 18-year-old females, and 2,600 mg of potassium for females that are 19 years of age and older.

For pregnant and lactating females, the AIs for potassium are: 2,600 mg of potassium for 14 to 18-year-old pregnant females, 2,900 mg for pregnant females that are 19 years of age and older; furthermore, 2,500 mg of potassium for 14 to 18-year-old lactating females, and 2,800 mg for lactating females that are 19 years of age and older. As for safety, the NAM also sets

tolerable upper intake levels (ULs) for vitamins and minerals, but for potassium the evidence was insufficient, so no UL was established.[23][24]

In 2019, the National Academies of Sciences, Engineering, and Medicine revised the Adequate Intake for potassium to 2,600 mg/day for females 19 years of age and older who are not pregnant or lactating, and 3,400 mg/day for males 19 years of age and older.[25][26]

The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. For people ages 15 and older the AI is set at 3,500 mg/day. AIs for pregnancy is 3,500 mg/day, for lactation 4,000 mg/day. For children ages 1–14 years the AIs increase with age from 800 to 2,700 mg/day. These AIs are lower than the U.S. RDAs.[27] The EFSA reviewed the same safety question and decided that there was insufficient data to establish a UL for potassium.[28]

Labeling

For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (%DV). For potassium labeling purposes 100% of the Daily Value was 3500 mg, but as of May 2016, it has been revised to 4700 mg.[29][30] A table of the old and new adult Daily Values is provided at Reference Daily Intake.

Supplements

20 mEq (781 mg) potassium from potassium gluconate (4680 mg), or potassium citrate (2040 mg), mixed a half-cup (1.12 dL) water, taken two to four times a day, may be used on daily basis.[31][32]

Labeling

Because of the risk of small-bowel lesions, the US

FDA requires some potassium salts (for example potassium chloride) containing more than 99 mg (about 1.3 mEq) to be labeled with a warning.[33]

Food sources

Eating a variety of foods that contain potassium is the best way to get an adequate amount. Foods with high sources of potassium include kiwifruit, orange juice, potatoes, coconut, avocados, apricots, parsnips and turnips, although many other fruits, vegetables, legumes, and meats contain potassium.

Common foods very high in potassium:[34]

  • beans (white beans and others)
  • dark leafy greens (spinach, Swiss chard, and others)
  • baked potatoes
  • dried fruit (apricots, peaches, prunes, raisins; figs and dates)
  • baked squash
  • yogurt
  • fish (salmon)
  • avocado
  • nuts (pistachios, almonds, walnuts, etc.)
  • seeds (squash, pumpkin, sunflower)

Foods containing the highest concentration:[34]

  • dried herbs
  • sun dried tomatoes
  • cocoa solids[35]
  • whey powder
  • paprika
  • yeast extract
  • rice bran
  • molasses
  • dry roasted soybeans

Deficiency

High blood pressure/Hypertension

Diets low in potassium increase risk of hypertension, stroke and cardiovascular disease.[36][37]

Hypokalemia

A severe shortage of potassium in body fluids may cause a potentially fatal condition known as

arrhythmia
.

In rare cases, habitual consumption of large amounts of black licorice has resulted in hypokalemia. Licorice contains a compound (Glycyrrhizin) that increases urinary excretion of potassium.[38]

Insufficient intake

Adult women in the United States consume on average half the AI, for men two-thirds. For all adults, fewer than 5% exceed the AI.[39] Similarly, in the European Union, insufficient potassium intake is widespread.[40]

Side effects and toxicity

Gastrointestinal symptoms are the most common side effects of potassium supplements, including nausea, vomiting, abdominal discomfort, and diarrhea. Taking potassium with meals or taking a microencapsulated form of potassium may reduce gastrointestinal side effects.

arrhythmia
), which can lead to cardiac arrest.

Although hyperkalemia is rare in healthy individuals, oral doses greater than 18 grams taken at one time in individuals not accustomed to high intakes can lead to hyperkalemia.

See also

References

  1. ^ Pohl, Hanna R.; Wheeler, John S.; Murray, H. Edward (2013). "Chapter 2. Sodium and Potassium in Health and Disease". In Astrid Sigel, Helmut Sigel and Roland K. O. Sigel (ed.). Interrelations between Essential Metal Ions and Human Diseases. Metal Ions in Life Sciences. Vol. 13. Springer. pp. 29–47.
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  3. ^ Milo, Ron; Philips, Rob. "Cell Biology by the Numbers: What are the concentrations of different ions in cells?". book.bionumbers.org. Archived from the original on 20 April 2017. Retrieved 23 March 2017.
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  25. ^ "Sodium and Potassium Dietary Reference Intake Values Updated in New Report; Introduces New Category for Sodium Based on Chronic Disease Risk Reduction" (Press release). National Academies of Sciences, Engineering, and Medicine. 5 March 2019. Retrieved 29 January 2022.
  26. S2CID 104464967
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  27. ^ "Overview on Dietary Reference Values for the EU population as derived by the EFSA Panel on Dietetic Products, Nutrition and Allergies" (PDF). 2017. Archived (PDF) from the original on 2017-08-28.
  28. ^ Tolerable Upper Intake Levels For Vitamins And Minerals (PDF), European Food Safety Authority, 2006, archived (PDF) from the original on 2016-03-16
  29. ^ "Federal Register May 27, 2016 Food Labeling: Revision of the Nutrition and Supplement Facts Labels. FR page 33982" (PDF). Archived (PDF) from the original on August 8, 2016.
  30. ^ "Daily Value Reference of the Dietary Supplement Label Database (DSLD)". Dietary Supplement Label Database (DSLD). Retrieved 16 May 2020.
  31. ^ "Potassium Supplement (Oral Route, Parenteral Route) Proper Use - Mayo Clinic". www.mayoclinic.org.
  32. ^ "NCATS Inxight Drugs — POTASSIUM GLUCONATE". drugs.ncats.io.
  33. ^ "Office of Dietary Supplements - Potassium". ods.od.nih.gov.
  34. ^ a b "Top 10 Foods Highest in Potassium + One Page Printable". myfooddata. Archived from the original on 2014-09-11.
  35. ^ "FoodData Central". fdc.nal.usda.gov.
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  39. ^ What We Eat In America, NHANES 2013-2014 Archived 2017-02-24 at the Wayback Machine.
  40. ^ "Archived copy" (PDF). Archived (PDF) from the original on 2011-07-13. Retrieved 2007-01-30.{{cite web}}: CS1 maint: archived copy as title (link) Energy and Nutrient Intake in the European Union

Further reading

External links

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