To reduce my panic attacks, I have done the following:-
1 Stop smoking - this is the most important of the lot - try lozenges rather than the gum (the lozenges give a more constant flow of nicotine, the gum may give big 'hits' of nicotine when chewed rapidly which can actually make panic attacks worse). People often smoke bacause they are stressed, though the feeling of stress you feel is often actually nicotine craving and not stress. If you continue to smoke your feelings of stress are unlikely to go away.
2 reduce caffeine intake - eg. try just having a coffee/tea/coke when you get in from work or try having half cups throughout the day instead of full ones
3 bananas - eat 3 bananas per day 1 for breakfast, 1 at 11 am and 1 in the afternoon - bananas give a steady release of energy and also contain sources of serotonin which can combat panic attacks. The energy from bananas will also enable you to reduce your caffeine intake.
4 avoid chocolate/foods/drinks high in sugar
5 reduce alcohol intake - eg. only drink at weekends
6 try and exercise regularly (also makes it easier to stop smoking)
I have tried all the above together and they have made a difference to the severity and frequency of attacks. I would be interested to know whether they help anyone else.
Best of luck
Scooby, UK.