I am currently developing a multiplayer html5 game, and the game has rpg elements (levels, items and such)

I just started working on the database side of things, and now I have a mongodb server setup with a basic user table (email, nickname, password hash and salt etc)

Now, each user should aquire items, and I am wondering should each user get his own collection in the db, or should there be a single collection that stores all the items, and has a email field that links the item to a user?