Identified in 1807 by Humphry Davy, potassium is found in nature in the human body (140g), in the earth's crust and in the oceans.
Potassium in the human body has fundamental functions as it regulates the flow of water into the cells as well as their osmosis.
Participates in the conversion of sugars, the metabolism of vital energy, the transmission of impulses in the central nervous system.
Potassium comes largely from fruits and vegetables and the potato is the highest source of potassium of all foods.
A transition toward modern ("Westernized") diets has led to a substantial decline of K+ intake compared with traditional food habits, and a large fraction of the population might now have suboptimal K+ intake. A high K+ intake was demonstrated to have protective effects against several pathologic states affecting the cardiovascular system, kidneys, and bones. Additionally, fruits and vegetables contain K/organic anion salts (malate, citrate), which exert alkalinizing effects (1). High potassium intake should always be prescribed by your doctor.
Because potassium is a major intracellular ion, it is widely distributed in foods once derived from living tissues. Potassium concentration is higher in fruits and vegetables than in cereals and meat. Salting foods and discarding the liquid induces sodium (Na+) for potassium (K+) exchange and reduces the potassium content of foods. Western dietary practices with higher consumption of cereal, low nutrient density processed foods and lower consumption of fruits and vegetables has led to a diet lower in potassium and higher in sodium in recent decades (2).
A recent study of half a million participants in China queried the relationship between fruit consumption (a rich source of diet K+) and cardiovascular disease and discovered lower blood pressure, blood glucose, and rate of cardiovascular deaths in participants that ate fruit frequently vs. rarely (3).
The feedback mechanism of potassium
There is a strong activity between potassium, sodium and extracellular fluid (ECF). This activity contributes to low extracellular fluid (ECF) K+ creating a source of stored potential energy that is used to drive action potentials, control muscle contractility, and power ion transporters. When ECF [K+] falls or rises, cell membranes hyperpolarize or hypopolarize, respectively, which disrupts normal electrical excitability and can lead to life-threatening cardiac arrhythmias. Thus the ECF [K+] is regulated, i.e., “K+ homeostasis,” within narrow limits by multiple renal and extrarenal mechanisms. ECF [K+] is controlled by feedback mechanisms (4):
- increased ECF [K+] stimulates renal K+ excretion by direct effects on renal tubule cells
- increased ECF [K+] promotes cellular K+ uptake, especially by muscle
The potassium / sodium ratio
Studies performed in the 1970s and 1980s established that potassium influences proximal sodium reabsorption. Contemporary studies have also confirmed that high dietary potassium decreases sodium reabsorption in the thick ascending limb (5).
Potassium intake
The latest strategies to increase potassium intake recommend the use of food instead of supplements (6).
Healthy benefits
- Hypertension
In 9585 Japanese hypertensive patients, potassium intake from fruits was associated with decreased systolic and diastolic blood pressure (7).
The DASH diet is well known and represents a food-based approach to increase potassium to levels recommended by the US Food and Nutrition Board. The DASH diet is rich in fruits and vegetables and dairy products and is effective in reducing blood pressure (8).
- Bone
Bone mass tends to peak around the third decade of life, after which a continuous decline of 0.7% per year is considered to be physiologic. K citrate supplementation induced positive effects on bone turnover while its indiscriminate use is not advisable since it does not add anything to the benefits induced by calcium and vitamin D (9).
- Kidney
Dietary potassium intake lowers blood pressure and is associated with decreased risks of cardiovascular morbidity, overall mortality and progression of renal disease. Some of the benefits from potassium are likely due to the interrelated handling of sodium and potassium in the kidney. Specifically, potassium inhibits sodium reabsorption by the kidney, while a low potassium diet enhances renal sodium reabsorption, even with a concomitant high sodium diet. Therefore, current guidelines recommend dietary potassium intake in the range of 90 to 120 mmol/day, well above usual intake in American and worldwide populations (5).
Where can we find potassium?
Selected food sources ranked by amounts of potassium and energy per standard food portion (10).
- 1 small baked potato of 143 g: 738 mg
- 1 cup of 256 g prune juice: 707 mg
- 1/4 cup of carrot juice from 236 g: 689 mg
- Yogurt 245 g: 531 mg
- Low fat milk: 154 mg
- Coffee: 135 mg
- Whole milk: 77 mg
- Pasta and pasta dishes: 72 mg
Potassium risk factors
In some patients excess dietary potassium intake results in hyperkalemia. Patients at risk include older patients and those with CKD, congestive heart failure, or diabetes mellitus, especially with concomitant use of medications that inhibit the renin-angiotensin-aldosterone system. Appropriate monitoring is required when using these beneficial medications in high-risk populations (5).
In chemistry it has the symbol K and is used:
- in the glass industry
- in cosmetics
- in medicine
Molecular formula: K
Molecular weight: 39.0983
CAS: 7440-09-7
References_______________________
(1) Protective effects of high dietary potassium: nutritional and metabolic aspects. Demigné C, Sabboh H, Rémésy C, Meneton P. J Nutr. 2004 Nov;134(11):2903-6.
(2) Potassium Intake, Bioavailability, Hypertension, and Glucose Control Michael S. Stone, Lisa Martyn and Connie M. Weaver Nutrients. 2016 Jul; 8(7): 444. Published online 2016 Jul 22. doi: [10.3390/nu8070444]
(3) Fresh Fruit Consumption and Major Cardiovascular Disease in China. Du H, Li L, Bennett D, Guo Y, Key TJ, Bian Z, Sherliker P, Gao H, Chen Y, Yang L, Chen J, Wang S, Du R, Su H, Collins R, Peto R, Chen Z, China Kadoorie Biobank Study. N Engl J Med. 2016 Apr 7; 374(14):1332-43.
(4) Potassium Homeostasis: The Knowns, the Unknowns, and the Health Benefits Alicia A. McDonough and Jang H. Youn Physiology (Bethesda). 2017 Mar; 32(2): 100–111. Published online 2017 Feb 15. doi: [10.1152/physiol.00022.2016]
(5) Potassium: Friend or Foe? Aylin R. Rodan Pediatr Nephrol. 2017 Jul; 32(7): 1109–1121. Published online 2016 May 18. doi: [10.1007/s00467-016-3411-8]
(6) Dietary Guidelines Advisory Committee Report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans, 2010. Washington, DC: U.S. Department of Agriculture, Agricultural Research Service, 2011
(7) Sodium intake in men and potassium intake in women determine the prevalence of metabolic syndrome in Japanese hypertensive patients: OMEGA Study. Teramoto T, Kawamori R, Miyazaki S, Teramukai S, OMEGA Study Group. Hypertens Res. 2011 Aug; 34(8):957-62.
(8) A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. Appel LJ, Moore TJ, Obarzanek E, Vollmer WM, Svetkey LP, Sacks FM, Bray GA, Vogt TM, Cutler JA, Windhauser MM, Lin PH, Karanja N N Engl J Med. 1997 Apr 17; 336(16):1117-24.
(9) Potassium Citrate Supplementation Decreases the Biochemical Markers of Bone Loss in a Group of Osteopenic Women: The Results of a Randomized, Double-Blind, Placebo-Controlled Pilot Study Donatella Granchi, Renata Caudarella, Claudio Ripamonti, Paolo Spinnato, Alberto Bazzocchi, Annamaria Massa and Nicola Baldini Nutrients. 2018 Sep; 10(9): 1293. Published online 2018 Sep 12. doi: [10.3390/nu10091293]
(10) Potassium and Health Connie M. Weaver Adv Nutr. 2013 May; 4(3): 368S–377S. Published online 2013 May 6. doi: [10.3945/an.112.003533]
Potassium 
