Quite simply; avoid it! The positive effect on anxiety levels by merely switching to decaf or herbal teas is completely under-rated - even if just trading in your morning fix.
I recently stumbled across Ayurveda as a means of trying to alleviate anxiety (hey, if it's good enough for Madonna and Kylie...!) and although I'm yet to fully put my treatment programme into place, the gasp of horror that came out of the consultant's mouth when I declared my morning coffee was enough to make me make that one adjustment there and then!!!