Hi I have a very high strung nervous horse, I have tried ground work, despooking,ect. He bolts through doors, can't stand calm for a minute. On the trails he thinks he has to move 90 miles an hour. He is an accident waiting to happen. Is there any supplements that work to calm him down?

Depending on your area, you may not have access to one.
The best thing I've found for those isn't a supplement but accupuncture.
Magnetics work some[usually the crown piece attachment] or a magnesium supplement. The best supplement Mag-Calm or Super-Mag, although Figuerola labs Equine Saver is a good overall sup.