Some people drink a cup of coffee in the morning and they're fine for the day. Others seem to need fixes all day long. Now researchers think they know why.
They found mutations in a gene that correlate very well with how much coffee a person drinks. People with one version drink just a little coffee, while people with another drink a lot — a whole lot.
The gene, called PDSS2, might control how quickly the body breaks down caffeine, the team reports in Nature Scientific Reports.
To find the new genetic pattern, the team led by Nicola Pirastu at the University of Trieste looked at people well known for their love of coffee — Italians and Dutch. Groups of volunteers in remote Italian villages and one in the Netherlands have been volunteering to have their entire genomes sequenced and studied for science.
Pirastu's team used these so-called genome-wide association studies to see if a gene might explain why some people drink so much more coffee than others.
"Our results have highlighted a novel gene associated with coffee consumption," they wrote.
"The identified gene has been shown to negatively regulate the expression of the caffeine metabolism genes and can thus be linked to coffee consumption."
There were big differences in how much coffee people drank. The Italians drank, on average, two to three cups a day while the Dutch drank nearly six a day. But some of that was due to how they made their coffee, the team said. The Italians drank espresso or strong perked "moka" coffee, while the Dutch preferred filtered coffee.
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Still, within the groups, those who had certain recessive mutations drank less coffee than others without those mutations. "People with a higher consumption of coffee have a lower expression of PDSS2," the team said. Genes with lower expression are less active.
Other genes have been linked with coffee consumption, so this one doesn't paint the whole picture, the team said. But it could help explain why some people need a regular pick-me-up in the late mornings or afternoons, they added.