You've probably heard of it about bananas.
Potassium is a mineral salt mainly intracellular, that is, it is found inside the cell while sodium is outside: these two salts work in pairs to maintain neuromuscular excitability, heart rhythm, osmotic pressure, acid-base balance and water retention.
Normally its plasma and body concentration is quite regulated, ipo o iper potassiemie they are rare unless there are particular pathologies such as kidney diseases, or if drugs are not taken. Symptoms of deficiency can be muscle hyperexcitability arrhythmias up to a heart attack.
Excesses instead they cause fatigue, muscle cramps, low blood pressure, slow heart rate and cardiac arrest. Therefore, note that both in the case of hyper and hypo-potassium the worst scenario that can occur is the heart.
A hypokalemia also results in increased sodium concentration and therefore hypertension. The two salts must necessarily be in equilibrium.
From a recent publication of the World Health Organization  it is recommended a correct potassium food intake in both adults and children necessary to maintain a correct blood pressure and avoid the risk of cardiovascular disease (3510 mg per day).
Also find out which foods are rich in potassium
Contained on average in some foods
Beans and peas - 1300 mg/100g
Walnuts, hazelnuts, cashews, brazil nuts - 600 mg / 100 g
Green vegetables (spinach, chard, parsley) - 550 mg / 100 g
Tubers (carrots, onions, beetroot) - 200 mg / 100 g
Other vegetables (Tomatoes, cucumbers, squash) - 300 mg/100g
Fruit (Bananas, papaya, dates) - 300 mg/100g
Friends of the heart and sportsmen
Coconut water: 1500 mg/L
Avocado: 485 mg / 100 g
Ananas: 109 mg / 100 g
 Potassium intake for adult and children GUIDELINES 2013
Fruit rich in potassium
To learn more:
> Natural potassium supplements: what they are and when to use them