Although I have not tried this personally, there is evidently to the folk remedy of using a banana peel to whiten your teeth. I might reconsider my hesitation to give it a try. All too often, many suggested home remedies have insufficient effect to make it worth the effort.
The premise is that the minerals present in the peel, such as potassium and magnesium, is absorbed by the ten minute application by rubbing the inside of a patch of peel directly on the teeth. I don’t believe the flavor of the peel would be appealing, but if the whitening effect has promise, it would very well worth a weekly effort as other alternatives tend to be far too abrasive. Some suggestions, such as paste that included baking soda and hydrogen peroxide, does whiten teeth well but will damage the edge of the gums if one cannot avoid the gums. Which is difficult in practice. Other than the obvious sugar concern, banana peel has relatively zero damage. Brushing after the peel application would take care of the sugars left behind.