Young businessman drinking coffee in a cafe

One of the world’s daily pleasures could have some interesting metabolic impacts, as a new study from investigators at Northwestern University Feinberg School of Medicine and several other research institutions shows that coffee affects a person’s metabolism in dozens of ways beyond the morning jolt—including the metabolism of steroids and the neurotransmitters typically linked to cannabis. Findings from the new study were released today in the Journal of Internal Medicine, in an article entitled “Metabolomic Response to Coffee Consumption: Application to a Three-Stage Clinical Trial.”

Interestingly, in the current study, these scientists were surprised to discover coffee changed many more metabolites in the blood than previously known. For instance, the research team found that the neurotransmitters related to the endocannabinoid system—the same ones affected by cannabis—decreased after drinking four to eight cups of coffee in a day. That's the opposite of what occurs after someone uses cannabis.

Cannabinoids are the chemicals that give the cannabis plant its medical and recreational properties. However, the body also naturally produces endocannabinoids, which mimic cannabinoid activity. Moreover, the scientists found that certain metabolites related to the androsteroid system increased after drinking four to eight cups of coffee in a day, which suggests coffee might facilitate the excretion or elimination of steroids. Because the steroid pathway is a focus for certain diseases, including cancers, coffee may influence these diseases as well.

“These are entirely new pathways by which coffee might affect health,” explained lead study investigator Marilyn Cornelis, Ph.D., assistant professor of preventive medicine at Northwestern University Feinberg School of Medicine. “Now we want to delve deeper and study how these changes affect the body.”

Unfortunately, little is currently known about how coffee directly impacts health. However, in this new study, Northwestern scientists tried to shed some light on coffee’s health effects by applying advanced technology that enabled them to measure hundreds of metabolites in human blood samples. The study generated new hypotheses about coffee's link to health and new directions for coffee research.

“We profiled the metabolome of fasting serum samples collected from a previously reported single-blinded, three-stage clinical trial,” the authors wrote. “Forty-seven habitual coffee consumers refrained from drinking coffee for one month, consumed four cups of coffee/day in the second month and eight cups/day in the third month. Samples collected after each coffee stage were subject to nontargeted metabolomic profiling using UPLC-ESI-MS/MS. A total of 733 metabolites were included for univariate and multivariate analyses.”

Interestingly, the researchers found that blood metabolites of the endocannabinoid system decreased with coffee consumption, particularly with those consuming eight cups per day. The endocannabinoid metabolic pathway is an important regulator of our stress response, and some endocannabinoids decrease in the presence of chronic stress.

“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,” Dr. Cornelis noted. “It could be our bodies' adaptation to try to get stress levels back to equilibrium.”

The endocannabinoid system also regulates a wide range of functions—cognition, blood pressure, immunity, addiction, sleep, appetite, energy, and glucose metabolism.

“The endocannabinoid pathways might impact eating behaviors,” Dr. Cornelis suggested. “The classic case being the link between cannabis use and the munchies.”

Coffee has also been linked to assisting weight management and reducing the risk of type 2 diabetes.

“This is often thought to be due to caffeine's ability to boost fat metabolism or the glucose-regulating effects of polyphenols (plant-derived chemicals),” Dr. Cornelis concluded. “Our new findings linking coffee to endocannabinoids offer alternative explanations worthy of further study.”

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