If you have high blood pressure does potassium like bananas really lower your blood pressure and if so how?

Potassium doesn't lower blood pressure. Why do you think you have high blood pressure? Each and every cell, especially the ones in the heart, use potassium to function. You can have serious health problems, including death if your potassium is too high or too low (both can cause serious and life threatening heart rhythms). Usually your kidneys will help you regulate potassium levels. To high or too low levels can be caused by taking loop diuretics (water pills), severe fluid loss through vomiting and/or diarhea, or kidney disease.