NEW YORK >> CNN’s Dr. Sanjay Gupta says he spoke too soon in opposing the medical use of marijuana in the past and that he now believes the drug can have very real benefits for people with specific health problems.

Gupta, the network’s chief medical correspondent and a brain surgeon, detailed his change of heart in an interview Friday and in an article for CNN’s website titled, “Why I changed my mind on weed.” He will narrate a documentary on the topic that will air on the network Sunday.

He wrote in Time magazine in 2009 about his opposition to laws that would make the drug available for medical purposes. “Smoking the stuff is not going to do your health any good,” he wrote then. But Gupta said Friday he too easily associated marijuana with “malingerers that just wanted to get high.”

Now he wants to say he’s sorry.

Gupta said he didn’t look hard enough at research on the topic, and found some new research that had been done since then. He was encouraged to look into the issue further upon meeting a 5-year-old girl in Colorado for whom medical marijuana has sharply cut down on the amount of seizures she had been suffering.

Time spent with her and others made him realize that medical professionals should be responsible for providing the best care possible, and that could include marijuana.

“We have been terribly and systematically misled for nearly 70 years in the United States, and I apologize for my own role in that,” he wrote.

The preponderance of the research done in the United States about marijuana is about what harm it could do. He said he’s found more research overseas that discusses the medical benefits.

While people die regularly from prescription drug overdoses, Gupta said he’s been unable to find a documented case of death from a marijuana overdose.

Gupta said he doesn’t want people to apply his change of heart to the issue of recreational marijuana use. As a father, he said he wouldn’t allow his children to smoke marijuana until they are adults. If they want to, he’d urge them to wait until their mid-20s when their brains are fully developed, because of studies that show the drug can damage young people.

But he said a prevalent attitude that people who want to use the drug for medicinal purposes are really interested in getting high is one of the things that holds back the widespread use of it for health reasons.

“I do think it’s good to separate the two of them,” he said.