Bananas are loaded with potassium, and researchers state that adding potassium may play a stronger role in the control of high blood pressure than restricting salt. Bananas also have a lot of magnesium, a mineral that helps keep blood pressure levels in check.
Generally, fruit is a poor source of vitamin B6, but bananas are the exception; a single serving has more than 30 percent of the recommended daily amount. Vitamin B6 helps to keep your immune system performing at its peak, and recent studies have found that, like a deficiency of folic acid, a long-term deficiency of vitamin B6 may increase your risk of heart disease.
Selection and Storage
There are different types of bananas, but Cavendish, the yellow bananas, are the most familiar. To appeal to a variety of cultures, supermarkets sometimes stock red bananas and plantains -- those seemingly underripe bananas that never lose their mossy green color.
Most bananas ripen after picking, and as they do, the starch in them turns to sugar. So the riper they are, the sweeter they are. Look for plump, firm bananas with no bruises or split skins. Brown spots are a sign of ripening. If your banana skins are tinged with green, allow them to ripen at room temperature (don't refrigerate unripe bananas; they'll never ripen); refrigerate them once they are ripe to stop the process. They'll turn an unsightly, but harmless, black color.