Bananas are packed with nutrients, especially potassium. An averaged-sized banana contains 440 mg of potassium and only 1 mg of sodium. Potassium is one of the most important electrolytes in the body, helping to regulate heart function as well as fluid balance. It is also a key factor in regulating blood pressure.
The effectiveness of potassium-rich foods, such as bananas, in lowering blood pressure and protecting against heart disease and strokes is well accepted and bolstered by considerable scientific evidence. For example, in one landmark study, researchers tracked more than 40,000 American male health professionals over four years to determine the effects of diet on blood pressure. Men who ate diets higher in potassium-rich foods had a substantially reduced risk of stroke.
Bananas are very soothing to the gastrointestinal tract due to their high content of pectin, a soluble fiber that not only lowers cholesterol, but normalizes bowel function. In addition, plaintain bananas have shown some promise in the treatment of peptic ulcers.