Why is it that some people crave several cups of coffee a day while others stop at only one or two?
A growing body of evidence suggests that the amount of coffee we consume is determined by our genetic makeup rather than the amount of sleep we got the night before.
Coffee is one of the most popular beverages worldwide, second only to tea and water, researchers say. And drinking hefty amounts of coffee has been associated with several health benefits.
Scientists have been studying the genetics behind coffee cravings since the 1960s. In 1962, they found that coffee-drinking habits appeared to be hereditary. More recently, large-scale studies have found an association between the amount of coffee people consume and a small handful of genes.
In a new paper published Thursday in Scientific Reports, a team of researchers describe the discovery of a gene variant that appears to limit coffee drinking.
The authors report that among more than 1,200 people living in Italy, those with the genetic variant PDSS2 tend to drink one fewer cups of coffee per day than those without the variation.
Further analysis revealed that expression of the PDSS2 gene appears to inhibit the body's ability to break down caffeine. If that's the case, people with this variant would require less coffee to get a strong caffeine jolt because the caffeine would linger in their system for a longer time.
To confirm their findings, the researchers replicated the study in a group of 1,731 people from the Netherlands. Although the results were similar, the effect on the number of cups of coffee people drank was slightly lower.
The authors of the paper say they would like to see their findings confirmed with even larger-scale studies. For now, however, they feel fairly confident that they have identified a gene that has never before been connected to coffee drinking.
"The results of our study add to existing research suggesting that our drive to drink coffee may be embedded in our genes," first author Nicola Piratsu, a genetics researcher at the University of Edinburgh in Scotland, said in a statement.
And you thought you were just tired.
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