Bananas are good for you because they are an excellent source of potassium; one medium-sized banana has 422 milligrams of potassium, which is 12 percent of the USDA recommended daily requirement, according to Health. Bananas are also rich in fiber, with three 3 grams per serving, and they provide nearly 20 percent of the daily recommended requirement for vitamins B6 and C.
In addition, bananas may play a part in weight loss since they are a good source of resistant starch that is used slowly by the body, making them a natural suppressant of the appetite and metabolic booster. Resistant starches like bananas encourage the liver to start burning fat. Slightly green bananas are the richest source of resistant starch, with more than twice the amount of resistant starch than ripe bananas.
The high potassium content in bananas may be helpful in regulating blood pressure since potassium helps move salt out of the body, according to Health. In the body, potassium helps the kidneys to let go of excess fluid and sodium.
Bananas are also a good source of prebiotics, which are carbohydrates that the body cannot digest. Prebiotics help to maintain a healthy gut because they supply food for probiotics and help good bacteria in the gut to grow. Other sources of prebiotics are garlic, onions, asparagus and raisins.