Why is a university even studying this?

Previous research has shown that a daily cup of joe may prevent diseases such as Parkinson’s and type 2 diabetes. But what happens at a metabolic level when people drink a lot—enough to create a medicinal benefit? That’s what Marilyn Cornelis, an assistant professor of preventive medicine at Northwestern University’s Feinberg School of Medicine, set out to discover: the impact coffee has on metabolites, the chemicals made or used when your body converts food and drink into energy. Discovering the coffee-cannabis link along the way was a happy accident.

So what does happen when you’re a java addict?

Participants in the study drank no coffee the first month (yikes), four cups a day the second month, and a teeth-rattling eight cups a day the third month. As intake increased, the levels of more than 100 of the 733 metabolites that Cornelis looked at changed significantly. Unexpectedly, though, she found that the metabolites known as endocannabinoids decreased.

Endocanna-what? That sounds like the part that has to do with pot.

Exactly. The body actually naturally produces endocannabinoids (named for cannabis because of their similarity to THC), which are neurotransmitters that regulate appetite, sleep, and mood, among other functions. They’re also part of the system that mediates marijuana’s effect on the body. When you smoke a joint, your endocannabinoid levels rise—the opposite of what happens when you drink coffee.

Will I still get stoned if I drink a cuppa while smoking weed?

Cornelis doesn’t know. But she hypothesizes that coffee might cancel out some effects of marijuana. Since caffeine is an appetite suppressant, for example, it might help you bypass the munchies.