Thioctic Acid
Sometimes called  alpha-lipoic acid
 is a natural anti-oxidant which has been used for years in Europe because of it's ability to help maintain or restore liver health. It's strong anti-oxidant capabilities have been used for radiation sickness and diabetes-related neuropathy.

In the pigeon world one product  is sold under the name brand of LEWERSTIM. 
I would want to know more about the claims being made on how it affects our pigoens, but the more a person learns about these products the better his pigeons race.