Researchers from the Harvard School of Public Health and Brigham and Women’s Hospital have identified six new genetic variants that have been linked to chronic coffee drinking.

The large-scale study sheds some light as to why a certain amount of coffee has various effects on different people. The findings of the study also offer fundamental information for future research identifying the association between coffee and overall well-being.

Lead study author Marilyn Cornelis, research associate in the Department of Nutrition at Harvard School of Public Health, and colleagues sought to look further into what role genetics play into individual differences in response to coffee. While genetics have long been known to be a contributing factor, identifying specific genetic variants has been a challenge.

The genome-wide study involved over 120,000 coffee drinkers with European and African backgrounds. Two specific genetic variants were identified and mapped to genes that are involved in the metabolism of caffeine, POR and ABCG2. Two genetic variants were discovered near genes BDNF and SLC6A4 that could be influential in the rewarding effects of coffee or caffeine.

The researchers concluded that people instinctively alter their coffee consumption in order to obtain the gratification provided by caffeine. The strongest genetic factors associated with coffee drinking probably work by directly boosting the metabolism of caffeine.

“Coffee and caffeine have been linked to beneficial and adverse health effects. Our findings may allow us to identify subgroups of people most likely to benefit from increasing or decreasing coffee consumption for optimal health,” said Cornelis.

The findings of the study are published online in Molecular Psychiatry.