the drinks got the attention of one of the biggest manufacturers not in a good way. she was told to back off for face a lawsuit. abc's bob woodruff has her story. >> reporter: it is the fastest growing segment of the beverage industry, energy drinks with high sugar and caffeine content. when nutritionist deborah kennedy publish a newsletter telling parents of elementary school children they should never allow energy drinks and they're dangerous and children have died from drinking them. monster fired back with a cease and desist letter as she tells dr. oz in an interview set to air next tuesday. >> basically said i have to retract the statement or they will threaten to sue me. i am a mom with two young kids. i think it is atrocious. >> reporter: dr. bob arnett is the company's medical consultant. >> keep in mind there is no evidence it caused any of this at all. >> reporter: what deborah kennedy was referring to was a highly publicized lawsuit claiming a 14-year-old, had died of cardiac arrhythmia caused by