Whilst I often extoll the benefits of varying your food, it turns out there's a particular reason not to eat huge amounts of bananas ... coming surprisingly from the Nuclear Threat Initiative think tank. They've started measuring radiation in Bananas ... no seriously! Using the Banana Equivalent Dose.
It turns out that Bananas are naturally radioactive ... but don't panic you don't have to avoid them - 400 (roughly hot docs annual banana intake) is the equivalent of a flight from London to New York. You'd have to eat 20 million to get radioactive poisoning, so I'm not recommending you stop eating them if you enjoy them ... it just serves as an amusing reminder that even healthy foods can be harmful in high doses.
It's not just bananas - there has been a case of someone dying from drinking excessive quantities of carrot juice due to vitamin A poisoning and someone dying from kidney failure from drinking 6 litres of water daily.
It's unlikely any of you would be so foolish but it is a caution to not get carried away with the latest food fads. There are always the latest superfood of the moment ... goji berries, acai, green tea, and it's great to incorporate these into your diet .. but just a sprinkle here or a handful there ... not huge amounts everyday!