Marijuana has long been used to treat the chronic pain and weight loss that comes with HIV, but a growing body of research suggests that using marijuana could potentially stop the spread of the virus itself.

Researchers at Louisiana State University recently conducted a study in which they gave a daily dose of THC to HIV-infected monkeys over the course of 17 months and discovered that immune tissue damage in the stomach was significantly slowed. "These findings reveal novel mechanisms that may potentially contribute to cannabinoid-mediated disease modulation," wrote researcher Dr. Patricia Molina. While HIV typically spreads by infecting and destroying immune cells, she explained, the THC-dosed primates maintained a higher-than-expected amount of healthy cells.

Marijuana has also been known to help the HIV-infected in other ways. A 2011 study also found that HIV-infected monkeys taking THC had a higher survival rate. In 2012, a study found that marijuana-like compounds fought HIV in late-stage AIDS patients.

Watch a monkey being administered a recreational dose of THC: