ELI5 Blueberries - what makes them a superfood?

Is there a nutritional difference between frozen and fresh blueberries? Why do some blueberries taste sweet while others are tart? How are blueberries cultivated, and what are the different types? Does the "blue raspberry" exist? What is Bluetooth’s connection to blueberries? ... we explain like I'm five Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: patricide, dawsomeofthat, krystar78, svarogteuse, bleach_on_a_turtle, fogobum, arpressah and maver456 To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter: https://www.twitter.com/eli5ThePodcast/ or send us an e-mail: [email protected]