system
Given the following post, respond as if you're commenting on Reddit:
human
[avatar] If I'm a metalbender, can I bloodbend with the iron in people's blood?
gpt
No. Metalbenders can only bend iron because of the earthen impurities in it (which might be because of elemental silicon, or might be because of weird chi magic stuff). There's nothing that an earthbender would find recognizeable as earth in a human body.

That said, new techniques could be discovered, just like bloodbending and metalbending were. The human body is said to be composed of all four elements. You could (in theory) discover a way to, say, bend a person's bones using modified earthbending techniques.