Apparently an amino acid called l-norvaline (suppresses argininase which shuts off nitric oxide production - supposed to increase blood flow and pumps) can be toxic to cells. Not sure exactly how the study was conducted. I’m sure if you dump enough of anything on cells, it’s toxic. I know there’s none of this in my black coffee I drink pre-workout. Just wanted to post and see what everyone’s thoughts were. Scary headline to get attention or legitimate study?