I've found it helpful to learn not to fuel thought trains. ACT (Acceptance and Commitment Therapy)[1] is helpful for that: It's basically about developing an understanding that thoughts and feelings are not real, and that they are not dangerous. A thought is the voice in your head, feelings are sensations in the body. Nothing more. It also has techniques that makes it easier to detect them.

By the way: Gut flora may play a role in anxiety[2], at least for some. It seems to play a role in many different mental, as well as physical, illnesses.

[1] http://www.amazon.com/The-Happiness-Trap-Struggling-Living/d...

[2] http://www.apa.org/monitor/2012/09/gut-feeling.aspx