Well the mature Granny Smith tree in my garden has nearly given me diabetes from the amount of crumble and pie that it has blessed us with and ruined the liver of many thanks to the reliable yearly cider production (affectionately known as "badger's arse" in the household). But at least my colon has friendly bacteria...
Yes precisely. I was hoping someone would reply with that.
The Granny Smith starts of as an acidic yellow ball of death, progresses through a window of being edible over the space of 2 days and then instantly turns into a rotten fermenting mushball suitable for cider only.
To get the things, you have to pick them early and check every day and add sugar to whatever you're cooking or they're inedible.
For reference, if you buy a Granny Smith in the shop and it's an eating apple, it's probably a hybrid and not a Granny Smith.
Nutrition: YMMV.