Coffee affects the same neurotransmitters in the brain as cannabis but in a very different way, according to a new study published in the Journal of Internal Medicine.
The benefits of drinking a morning cup of java – one of the most widely consumed beverages in the world – is well-published in the scientific community, from potentially helping you live longer to promoting heart and skin health. Now, researchers suggest that coffee affects the metabolism in a number of ways by changing metabolites, small molecules found in our blood and responsible for a variety of functions throughout the body, and by proxy affecting neurotransmitters related to the endocannabinoid system typically linked to the use of cannabis.
The body’s endocannabinoid system plays a role in regulating our mood and physiology and has been shown to help regulate our stress response, as well as functions like cognition, blood pressure, immunity, addiction, sleep, appetite, and energy. When consumed, cannabis binds to neurotransmitters (chemicals that deliver messages between our nerve cells) related to the endocannabinoid system, which has been linked to a long list of health benefits. As it turns out, coffee binds to these same neurotransmitters but decreases after drinking four to eight cups of coffee per day – the opposite of what happens when someone uses cannabis.
To find out how coffee impacts the body, researchers measured the metabolites in blood samples taken from 47 people living in Finland over the course of three months. In the first month, study participants abstained from drinking coffee altogether. In the second month, participants drank four cups of coffee daily, followed by eight cups a day in the third month. Researchers measured more than 700 metabolites in the blood after each stage and found a total of 115 that were significantly associated with drinking coffee; 82 of these were known and mapped – specifically those associated with metabolizing caffeine, polyphenols (chemicals that occur in plants), and steroids.
“The increased coffee consumption over the two-month span of the trial may have created enough stress to trigger a decrease in metabolites in this system,” said study author Marilyn Cornelis, from Northwestern University Feinberg School of Medicine, in a statement. “It could be our bodies’ adaptation to try to get stress levels back to equilibrium.”
Because our endocannabinoid system also regulates functions like appetite, this link could help explain one of marijuana’s most well-known side effects.
"The endocannabinoid pathways might impact eating behaviors," said Cornelis, “the classic case being the link between cannabis use and the munchies.”
Researchers also found that certain metabolites impacted by coffee are related to the androsteroid system, meaning coffee could help excrete or eliminate steroids from the body, like those used in the treatment of cancer and other diseases.
The team are quick to caution that coffee contains hundreds of other compounds and they're not sure whether it’s a specific compound found within coffee, caffeine, or a combination of the two that accounts for these relationships. Furthermore, the study notes a number of limitations, including study design without randomization, placebo control, as well as a lack of guidelines when it comes to how coffee is consumed, such as adding sweetener or cream.