How many cups of coffee do you take in one day?

For some, a cup or two can already complete their daily morning routine. Others, however, seem to have tummies that can withstand five to 10 cups of Joe all day long.

As it turns out, this craving for coffee may actually be rooted in a person's DNA. According to a new study, our genes influence our coffee fixes and a specific gene mutation may be to blame.

A Cup Of Coffee A Day

Scientists from the University of Edinburgh analyzed genetic data involving 1,200 people in Italy who were surveyed on how much coffee they drink every day. Specifically, 370 participants were from a small village in south Italy, while the remaining 843 were from six northeastern Italy villages.

Led by Nicola Pirastu, researchers sequenced and studied the genomes of each participant, using genome-wide association to see whether it might explain why some people drink so much more coffee than others.

The study found that participants with a genome variant called PDSS2 consumed one cup less a day than participants who lacked the gene variant. This meant that those with the PDSS2 gene variant appeared to have fewer coffee consumption.

"People with a higher consumption of coffee have a lower expression of PDSS2," the team wrote.

To confirm their findings, researchers replicated their study in another group of 1,731 participants from the Netherlands. The results were similar, but the effect of the gene variant on the number of coffee cups consumed was slightly lower.

Italians drank an average of two to three cups of coffee, while the Dutch drank nearly six cups every day. This gap in average coffee consumption may be due to the different styles of coffee drunk in Italy and the Netherlands, scientists say.

In Italy, people prefer to drink smaller cups such as strong perked "moka" coffee or espresso, while in the Netherlands, people tend to take in bigger cups with more caffeine.

Impact Of The Gene Variant

Pirastu and colleagues say the PDSS2 DNA variation hinders the breakdown of caffeine, causing it to remain in the body much longer. This meant that a person need not consume as much coffee to get the same caffeine fix.

The findings of the study contribute to previous studies that suggest our drive for coffee may be embedded in our DNA, says Pirastu. And although the report does not paint a whole picture, it does explain why people need a pick-me-up during mornings or afternoons.

Meanwhile, Pirastu says they need to conduct larger studies to further confirm their results and to clarify the link between coffee consumption and PDSS2.

Details of the research are published in the journal Scientific Reports.

Photo: Vesselin Dochkov | Flickr

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