Genetics may explain how much coffee is too much: study

Boston, Mass. – Why is it some people need and can consume several cups of coffee and others are left jittery after just one cup?

A new study led by the Harvard School of Public Health and Brigham and Women’s Hospital researchers may help to explain why different amounts of coffee or caffeine has different effects on different people.

On the Harvard School of Public Health website, Marilyn Cornelis, who is research associate in the Department of Nutrition and lead author of the study, explains that “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.”

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

However, pinpointing the specific genetic variants has been challenging.

Study

The researchers, who are 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.

What they found was the two variants that mapped to genes involved in caffeine metabolism; two variants were identified near other genes that potentially influence the rewarding effects of caffeine; and two other variants near genes involved in glucose and lipid metabolism, which had not previously been linked to the metabolism or neurological effects of coffee.

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,” says Cornelis.

Daniel Chasman, associate professor at Brigham and Women’s Hospital and the study’s senior author, adds that “like previous genetic analyses of smoking and alcohol consumption, this research serves as an example of how genetics can influence some types of habitual behaviour.”

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