User blog comment:SayuriDarling/The Mark of Athena Official Discussion/@comment-4485028-20121003210128/@comment-3146930-20121003210322

I think only if he swallows them. If I remember correctly, he was opening the seeds and placing them in his mouth, but spit them out when the next day came, so he isn't actually eating any Underworld food. If I'm wrong, well then he spends a lot of time in the Underworld anyway so it shouldn't be much different