Blame your genes for your addiction to coffee

Researchers have found six new genetic variants that determine how humans react to caffeine.

The genome- wide meta-analysis, led by Harvard School of Public Health and Brigham and Women's Hospital researchers, helped explain why a given amount of coffee or caffeine has different effects on different people and provided a genetic basis for future research exploring the links between coffee and health.

The researchers, part of the Coffee and Caffeine Genetics Consortium, conducted a genome-wide meta-analysis of more than 120,000 regular coffee drinkers of European and African American ancestry.

They identified two variants that mapped to genes involved in caffeine metabolism, POR and ABCG2 (two others, AHR and CYP1A2 had been identified previously). Two variants were identified near genes BDNF and SLC6A4 that potentially influence the rewarding effects of caffeine. Two others, near GCKR and MLXIPL, genes involved in glucose and lipid metabolism had not previously been linked to the metabolism or neurological effects of coffee.

The findings also suggested that people naturally modulate their coffee intake to experience the optimal effects exerted by caffeine and that the strongest genetic factors linked to increased coffee intake likely work by directly increasing caffeine metabolism.

Marilyn Cornelis, research associate in the Department of Nutrition at Harvard School of Public Health, said that coffee and caffeine have been linked to beneficial and adverse health effects many times and their findings allowed them to identify subgroups of people most likely to benefit from increasing or decreasing coffee consumption for optimal health.

The study is published online in Molecular Psychiatry.