Potassium - along with sodium, it regulates water management in the organism, ensuring normal heart rate. Maintaining the right level of potassium causes normal brain oxidation, reduces blood pressure, increases cell membrane permeability (as calcium antagonist). It is a base-forming element. It is commonly applied in pre- and post-workout sport diet as supplements, nutrition products, vitamin and mineral preparations, mineral preparations, concentrates and ready isotonic and hypertonic sports drinks. Natural sources of potassium are products of plant (bananas, citrus, melons, mint leaves, green vegetables, potatoes) and animal origin (marine fish, meat). Potassium occurs as organic compounds: citric acids, fumarates and gluconates, and non-organic compounds (chlorides, sulphates, oxides and carbonates).