A banana a day may keep heart disease away. Bananas contain high levels of potassium, a mineral that promotes healthy muscle, kidney, blood””and heart””function.
Potassium is an electrolyte, a positively-charged molecule that works with other electrolytes, such as sodium and chloride, to help regulate the body’s fluid levels. It also stimulates muscle contraction and helps the body maintain a stable acid-base level.
Because the blood’s concentration of potassium is small, even slight changes can have significant effects on the body. Low levels, a condition called hypokalemia, may occur when large amounts of fluid are lost from the body, such as with severe sweating, vomiting, or diarrhea. Muscle cramps and fatigue can result, or, in more serious cases, paralysis and abnormal heart rhythm.
The development of high potassium levels is rare, as the body can safely absorb up to 18 grams per day (a banana has about 400 mg). The condition, called hyperkalemia, could happen with improper potassium supplementation or abnormal kidney function.
Most people obtain the proper amount of potassium in their diets. Besides bananas, orange juice, sweet potatoes, cantaloupe, honeydew, spinach, beets, carrots, and legumes are all good sources.