Potassium is a mineral involved in electrical and cellular body functions. It plays various roles in metabolism and is essential for the proper function of all cells, tissues, and organs. Adequate potassium helps to maintain lower blood pressure levels, reduce the effects of sodium intake on blood pressure, prevent kidney stones, decrease bone loss, and improve glucose metabolism.
For athletes, potassium's role is of particular importance because potassium helps regulate fluids and mineral balance and is needed for muscle contractions and transmission of nerve impulses.

Specifically, potassium:
Assists in the regulation of the acid-base balance.
Assists in protein synthesis from amino acids and in carbohydrate metabolism.
Is necessary for the building of muscle and for normal body growth.

A deficiency of potassium (hypokalemia) can occur in people with certain diseases or as a result of taking diuretics for the treatment of high blood pressure, heart failure, or weight loss. Therefore, athletes with eating disorders, or those wrestlers and others who are trying to make weight, may be at an increased risk. Diuretics are probably the most common cause of hypokalemia.
A variety of conditions can cause the loss of potassium from the body. The most common of these conditions are vomiting and diarrhea. Additionally, many medications such as diuretics, laxatives, and steroids can cause depletion of potassium.

The most common symptom of potassium depletion is fatigue. Other symptoms of potassium deficiency include slow reflexes, muscle weakness, and EKG changes. A quick loss of potassium could lead to cardiac arrhythmias and even death.

Taking in a potassium supplement is not necessary as this mineral can be readily obtained through a variety of food sources. Fish such as: salmon, cod, flounder, and sardines are good sources of potassium. Various other meats also contain potassium. Vegetables including: broccoli, peas, lima beans, tomatoes, potatoes (especially their skins), and leafy green vegetables such as spinach, lettuce, and parsley contain potassium. Fruits that contain significant sources of potassium include: citrus fruits, apples, bananas, and apricots.
There is no upper level set for potassium, as food sources of potassium have not shown to reach toxic levels. On the other hand, supplemental potassium can lead to acute toxicity in otherwise healthy individuals.