GBL (gamma butyrolactone)
GBL is claimed to build muscles, reduce weight, improve athletic and sexual performance, reduce stress and improve sleep.
GBL affects the central nervous system and can slow breathing and heart rate to dangerous levels, leading to seizures, unconsciousness, coma and vomiting. At least 55 adverse health effects, including one death have been reported. The Food and Drug Administration stated that in 19 of those cases, the consumers became unconscious or comatose. The FDA has asked dietary supplement manufacturers to recall products containing this chemical. Consumers should not purchase or consume products that contain this ingredient.