In 24 hour races I tend to develop an upset stomach. By upset I mean a heavy, bloated feeling. Almost like you have to burp to get some relief but you can't.
The usual result is I can't eat or drink for a while. I've realized that the issue tends to come up when I start getting tired and want to close my eyes. Anyone else have this issue? I'm wondering if my body is shutting down and telling me I need to get some shut-eye.
You should try Foosh. It's like a caffeinated altoid that also calms your stomach. They've saved me more than once.
http://www.vroomfoods.com/foosh_mints.html