In his review of the final novel in the trilogy, critic David Camp comments on the constant coffee drinking featured in Stieg Larsson's novels. Irreverently (but hilariously) he says,
Many of the Larsson faithful subscribe to a belief that [Stieg Larsson] was made dead by the very sorts of heavies who crop up in his novels. But such talk has been emphatically dismissed by Larsson's intimates. So let me advance my own theory: Coffee killed him. If we accept that Blomkvist is, in many respects, a romanticized version of Larsson, and that Blomkvist's habits reflected the author's own, Larsson overcaffeinated himself to death. (source)
Well, we might point out that you could view coffee is a symbol of alertness, a necessary quality for solving mysteries. Of course, it also symbolizes artificially keeping the body awake when it should be sleeping. The characters in Larsson's novels have to drink lots of coffee. How else could we explain their ability to continue to function after days of missed sleep?
Some readers respond to Camp's review with the argument that people in Scandinavian countries simply drink more coffee than people in the US; that this is a cultural thing. Hmm…Now that's rather hard to fathom considering the Starbucks on every corner, isn't it. Plus, the US has its very own mystery writer who relies just as much on coffee as Larsson. That would be Walter Mosley, author of the acclaimed Easy Rawlin's mysteries. In those novels, you'll find just as many coffee cups, coffee thermoses, and coffee addicts as in Larsson's.