A deficiency of potassium is uncommon but it is an important mineral because of its role in maintaining water and acid balance in the body. It is also involved in maintaining a normal heart rate and in the transport of materials in and out of the cells. Clinical signs of deficiency rarely occur because nutrient sources contain adequate amounts. However when they do emaciation, reduced appetite and incoordination are seen. Excess potassium in the diet may precipitate colitis.