Have one a day for part of your five daily fruit and veg.
You don't need to eat many bananas per day for good health. For example exercise fr at least 30 mins a day and make sure you eat healthy ( thats where the bananas come in). It is okay to have a little snack once in a while but not to often! Also remember to drink a lot of water! Good luck
I'd go for 1 banana a day. Don't forget the well known saying: "An apple a day keeps the doctor away". I'd go for that train of thought to stay nice and healthy.