Jim McMahon speaks at a Players Against Concussions event in 2014. (Eugene Gologursky/Getty Images for Players Against Concussions)

Quietly, the NFL has shown interest in the campaign that Eugene Monroe has waged to raise awareness of medical marijuana as an alternative to opioid painkillers, and a Super Bowl winner has chimed in with the same message.

Jim McMahon, who won Super Bowl XX with the Chicago Bears, said that the plant has helped him cope with the early onset of dementia as well as severe headaches, memory loss, depression and other issues that have been linked to the kinds of concussions he suffered over the years.

“There’s so many uses to this plant,” McMahon said at last week’s Cannabis World Congress and Business Expo in New York (via the New York Daily News). “Hundreds of thousands of people are dying from [painkillers] and there’s not one case of people dying from the hemp plant.”

Leonard Marshall, who has neurological issues and formerly played for the New York Giants and Jets and Washington Redskins, agreed, saying, “My quality of life has improved because of this.”

Monroe’s vocal advocacy comes at a time of increasing awareness of the toll of addiction to opioids and shifting attitudes about the legalization of marijuana. Recently, Jeff Miller, the NFL’s senior vice president for player health and safety, and neurological surgeon Russell Lonser, a member of the league’s head, neck and spine committee, spoke with researchers Monroe has backed with $80,000 in funding.

“They are interested in learning more about the potential for cannabinoids to help current and former players, as is evidenced by them taking the call, and also expressed a desire to learn more,” Marcel Bonn-Miller, an adjunct assistant professor at the University of Pennsylvania school of medicine, told The Post’s Adam Kilgore recently. “They are definitely showing genuine curiosity, and they are definitely not throwing up roadblocks.”

Marijuana, however, remains on the NFL’s list of banned substances.

“It’s an NFL policy and we believe it’s the correct policy, for now, in the best interest of our players and the long-term health of our players,” Commissioner Roger Goodell said a Super Bowl press conference in February. “I don’t foresee a change in that clearly in the short term.”

It may help save the NFL, though. Research has suggested but not yet proved that cannabis may play a role in preventing and treating concussions. Cannabidiol, or CBD, has been shown to have analgesic and anti-inflammatory as well as neuroprotective properties. Animal research indicates CBD could protect neurons and mitigate effects from concussions.

“We have no guarantee this is going to work,” Lester Grinspoon, a professor emeritus at Harvard and one of the first medical marijuana researchers, told Kilgore. In fact, he says players should take it before games. “But if you can take anything away, evidence shows it is neuroprotective. I would have each individual take a capsule an hour or two before they play or practice. It’s better than nothing.”

To be clear, Monroe is talking about the use of medical marijuana.

“I’m not here advocating for NFL players (or anyone) to get high and party while breaking the law,” he wrote on The Players’ Tribune last mont. “What I’m talking about is the responsibility of the NFL to care for its players. Nineteen players were suspended last season for testing positive for “substances of abuse,” and for some, their careers may be over. Why? For using something that can actually help people? How can a league so casual about the use of addictive opioids take such a hard line on a drug that might provide a safer alternative?”

Monroe, the first active player to actively campaign for medical marijuana, is now a free agent after his release, which was fueled in part by his injury history and high salary, last week.

“Despite the current uncertainties,” he tweeted, one thing is for sure: whatever happens in terms of my professional football career, I will never stop pushing for the League to accept medical cannabis as a viable option for pain management. I will do everything I can to ensure the generations of NFL players after me won’t have to resort to harmful and addictive opioids as their only option for pain management.”