http://www.cnn.com/2013/08/09/health/gupta-weed-reaction/index.html CNN chief medical correspondent Dr. Sanjay Gupta spent a year traveling around the world to shed light on the debate about marijuana. Catch his groundbreaking documentary "WEED" at 8 p.m. ET Sunday on CNN. (CNN) -- It was the pot story read around the world. Dr. Sanjay Gupta is used to making headlines. The brain surgeon and CNN's chief medical correspondent can't even leave his office and walk through CNN Center without tour groups stopping him to take his picture or compliment his work. But this time the intensity of interest in a story he wrote for CNN.com about how he changed his mind about the effectiveness of medical marijuana was something even he didn't anticipate. "The attention has been pretty intense, and I was a little surprised," Gupta said. "I know it's a provocative topic, but the science is there to back it up."