A large team of researchers who are part of the Coffee and Caffeine Genetics Consortium has identified six new genetic variants associated with habitual coffee consumption.

Genetics have long been suspected of contributing to individual differences in response to coffee and caffeine.

However, pinpointing the specific genetic variants has been challenging.

Previous studies have identified only two genetic variants associated with habitual caffeine and coffee consumption – near genes CYP1A2 (cytochrome P450 1A2, responsible for about 95 per cent of caffeine metabolism in humans) and AHR (aryl hydrocarbon receptor, plays a regulatory role in expression of target genes, including CYP1A1 and CYP1A2).

Now, a genome-wide meta-analysis of regular-type coffee drinking (cups per day) among up to 130,000 participants of European and African-American ancestry has confirmed associations with AHR and CYP1A2 and identified six new genetic variants, not previously implicated in coffee drinking behavior.

The scientists identified two variants that mapped to genes involved in caffeine metabolism, POR and ABCG2.

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.

“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 Dr Marilyn Cornelis of Harvard School of Public Health, who is the lead author of the paper published in the journal Molecular Psychiatry.

The findings suggest 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.

“The new candidate genes are not the ones we have focused on in the past, so this is an important step forward in coffee research,” Dr Cornelis said.

“Like previous genetic analyses of smoking and alcohol consumption, this research serves as an example of how genetics can influence some types of habitual behavior,” said Dr Daniel Chasman of Brigham and Women’s Hospital, who is the senior author of the paper.

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M C Cornelis et al. Genome-wide meta-analysis identifies six novel loci associated with habitual coffee consumption. Molecular Psychiatry, published online October 07, 2014; doi: 10.1038/mp.2014.107