Hi ad30. Welcome to Psych Central. You are not alone. Many people complain about this.
google "how does st john's wort work flatulence" and there are many hits.

Here is one explanation
Many people here at PC find they can share these feelings and what they are going through with the confidence that people go through similar things and can empathize. So many forums are offered as well as Chatrooms (after you have 5 posts or comments on others posts). Depression chat meets on Thursday night at 9pm EST and Anxiety Friday at 8PM EDT EST.

You can also be an active member in other ways like supporting others in their questions, reading articles and posts http://forums.psychcentral.com that are applicable to your area of concern.

Please feel free to private message me or any of the Community Liaisons by left clicking on the name in blue to the left of their post) for questions or just to share.