Potassium is involved in nerve function, muscle control and blood pressure. Research suggests that the ratio of sodium to potassium in the diet may be more important than the specific amounts of sodium or potassium. A diet low in potassium and high in sodium may be a factor in high blood pressure. Increasing potassium in the diet may protect against hypertension in people who are sensitive to high levels of sodium. Athletes also may need more potassium to replace that lost from muscle during exercise and the smaller amount lost in sweat.
Low potassium can cause muscle cramping and cardiovascular irregularities.
Eating foods high in potassium can prevent these symptoms. One cup of orange juice, a banana or a potato is sufficient to replace the potassium lost during one to two hours of hard exercise. Sport drinks are poor sources of potassium. Potassium works with sodium to maintain the body's water balance. One possible explanation for potassium's protective effect against hypertension is that increased potassium may increase the amount of sodium excreted from the body.