One idea might be to look to IBS [Irritable Bowel Syndrome] diet tips and such. Last I was reading about it, and admittedly that was a WHILE ago, there seemed to be suggestion that a lot had to do with mood and so serotonin and that played into at least part of it [though not all].

I mean my theory is that people with IBS who commonly find that certain foods are triggers may give you a clue as to what kind of foods may or may not ease the transition for your body.

It's just a thought.

Google results lists:
IBS trigger foods

IBS diet recommendations

managing mild to moderate IBS

Sorry is that helpful or annoying? I just thought it might be easier if you haven't had much knowledge, experience with IBS. But again, just an idea?

Hope you can figure out a way to work it.

-Josie