It has long been assumed that genes play a contributing role to the varying responses to individuals consuming caffeine and coffee, but it has been a challenge for researchers to isolate the specific genes related to it.

However, a recent study spearheaded by researchers from the Harvard School of Public Health and the Brigham and Women’s Hospital has identified six new genetic variants found to have relationship with habitual drinking of coffee.

"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," study’s lead author Marilyn Cornelis says in a statement.

The study’s “genome-wide meta-analysis” can help explain the reason why caffeine or coffee in particular amounts has diverse effects on varied people and can provide a genetic basis needed for research in the future that will explore the relationship between our health and coffee.

Researchers who are involved in the Coffee and Caffeine Genetics Consortium conducted the said meta-analysis involving over 120,000 regular drinkers of coffee who are of African American and European lineage.

Results of the findings suggest that people control their intake of coffee naturally to feel the optimal effects of the caffeine. It also says “the strongest genetic factors linked to increased coffee intake likely work by directly increasing caffeine metabolism.”

The researchers identified two genetic variants—ABCG2 and POR—mapping to genes engaged in metabolism of caffeine. Two other genetic variants—CYP1A2 and AHR—were previously identified already.

Two identified variants near SLC6A4 and BDNF genes possibly influence caffeine’s rewarding effects. The others, near MLXIPL and GCKR genes, that are engaged in lipid and glucose metabolism weren’t connected to coffee metabolism or its neurological effects.

Cornelis, who is a research associate at the Department of Nutrition in Harvard School of Public Health, says the new candidate genetic variants aren’t the ones they focused on previously, which makes it a crucial step in researching about coffee.

Study’s senior author Daniel Chasman, also an associate professor at Brigham and Women’s, says the new research “serves as an example of how genetics can influence some types of habitual behavior."

“Our genetic findings among European and African-American adults reinforce the role of caffeine in mediating habitual coffee consumption and may point to molecular mechanisms underlying inter-individual variability in pharmacological and health effects of coffee,” says the abstract of the study.

The study, Genome-wide meta-analysis identifies six novel loci associated with habitual coffee consumption, was recently published online in Molecular Psychiatry journal.

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