Consider your caffeine intake. Also, when it comes to herbal teas, some are not recommended or should be limited, so that's worth looking at. My diet didn't really change a lot, I just followed my body. One thing I had lots of in first trimester was thin lentil soup - just carrot, celery, lentils and stock, puréed and frozen in mugs, so I could just heat it up and have it ready to go.

I have heard the allergy thing but I think the current recommendation is not to avoid anything.