Potassium

Figure 1. The crystal structure of Potassium.

Potassium is a chemical element with the symbol K and atomic number 19. Potassium is the 17th most abundant element by weight in the Earth. It makes up about 2.6% of the weight of the earth's crust and is the seventh most abundant element in the crust. Chemically, Potassium is very similar to sodium. Potassium is the eighth or ninth most common element by mass in the human body. A 60kg adult contains about 120 g of potassium. 

Potassium ions are vital for the functioning of all living cells. It is sometimes referred to as an electrolyte because it carries a small electrical charge (i.e. as an ion) that activates various cell and nerve functions. The transfer of Potassium ions across nerve cell membranes is necessary for normal nerve transmission. As such, Potassium deficiency and excess can each result in numerous signs and symptoms, including an abnormal heart rhythm and various electrocardiographic abnormalities. Potassium ions are also present in a wide variety of proteins and enzymes.

Food Sources

Potassium is widely available in many foods, especially fruits and vegetables. Food sources for Potassium include:

• Dried fruits (raisins, apricots)
• Beans, lentils
• Potatoes
• Winter squash (acorn, butternut)
• Spinach, broccoli
• Beet greens
• Avocado
• Bananas
• Cantaloupe
• Oranges, orange juice
• Coconut water
• Tomatoes
• Dairy and plant milks (soy, almond)
• Yogurt
• Cashews, almonds
• Chicken
• Salmon

Taken as a Dietary Supplement

As an electrolyte, Potassium assists in a range of essential body functions. In humans, at least 400mg-800mg of Potassium is needed daily because of normal daily losses. As such, Potassium is often promoted as a supplement for helping with:

• blood pressure
• normal water balance
• muscle contractions
• nerve impulses
• digestion
• heart rhythm
• pH balance (acidity and alkalinity)

Potassium is also promoted as treatment for Potassium deficiency, or kypokalemia. Certain conditions and diseases can cause hypokalemia, including:

• kidney disease
• overuse of diuretics
• excessive sweating, diarrhea, and vomiting
• Magnesium deficiency
• use of antibiotics, such as carbenicillin and penicillin

The kidneys work to maintain normal blood levels of Potassium by flushing out excess amounts through urine. Potassium can also be lost through stool and sweat. While rarely occurring, too much Potassium can cause hyperkalemia. Symptoms of hyperkalemia include an abnormal heartbeat (or arrhythmia).

Hyperkalemia may be caused by:

• taking too many potassium supplements
• kidney disease
• prolonged exercise
• potassium-conserving diuretics
• chemotherapy
• diabetes
• severe burns