Researchers from India verified that when you barbecue meat, it produces all sorts of carbon nanoparticles, including graphene oxide. This led them to the conclusion that GO is probably safe to eat - as humans have been eating barbecued meat for thousands of years.
When meat is heated, the proteins undergo pyrolysis, which produces graphene oxide sheets and carbon nanoparticles via the condensation of five- and six-membered rings. Some of these particles are doped with nitrogen from the atmosphere, and GO is formed when plant matter is charred. GO is also present in several medicines such as gripe water and active coal powders.