What did Itachi make Naruto eat?

I remembered in one of the Shippuuden episodes, Itachi put Naruto into a genjutsu and made Naruto eat a black crow? Some people are saying that Itachi is leaving a message for Sasuke when he is going to triumph over Naruto in their last battle, which will make him change his heart and protect Naruto from Madara. I dont know but it is pretty interesting. What do you guys think?