Scientists have found a gene that appears to have an influence over the amount of coffee people drink, and how the body processes caffeine

A gene that appears to wield influence over the amount of coffee people drink has been found by scientists who believe the section of DNA alters how caffeine is broken down in the body.

Italian villagers who carry a specific variant of the PDSS2 gene consume about one less cup of coffee per day compared with non-carriers, according to researchers at Edinburgh University.



The gene variant appears to affect people’s coffee intake by slowing the metabolism of caffeine in the body. When caffeine is broken down more slowly, the stimulant lingers in the blood for longer and gives people a more enduring “hit” for every cup.



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Nicola Pirastu, a geneticist who led the study, said the discovery reinforces the idea that caffeine is one of the main drivers for drinking coffee. But he added that larger studies are needed to confirm the biological mechanism that links the PDSS2 gene to coffee drinking.



Previous searches for genes linked to coffee consumption have already thrown up more than half a dozen variants that hold sway over the metabolism and rewarding effects of caffeine. In teasing out the genetics of coffee drinking, scientists hope to learn more about the unexplained effects of the drink. “Coffee is protective against some types of cancers, cardiovascular diseases and Parkinson’s,” said Pirastu. “Understanding what is driving its consumption may help us understand what the effects on these diseases are, and so open new lines of research.”



In the study, researchers analysed the genetic makeup of 370 people living Puglia in southern Italy and a further 843 from six villages in the Friuli Venezia region in the north east. All were asked to complete a survey, which included a question about how many cups of coffee they drank each day.



The researchers found that people with a specific variant of the PDSS2 gene tended to drink fewer cups of coffee than those who carried other variations of the gene. To check the result, the researchers went to 1731 people in the Netherlands and found a similar effect, though the gene’s apparent influence over coffee consumption was weaker there.



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One explanation could be that national preferences for coffee differ in Italy and the Netherlands. While moka and espresso are popular in Italy, the Dutch favour more filter coffee. And even though the concentrations of caffeine in the drinks are much the same, the difference in cup sizes means the Dutch imbibe nearly three times as much caffeine per cup as the Italians.



Published in the journal Scientific Reports, the study drew on researchers from Edinburgh, Trieste and the Netherlands. The Italian coffee company Illy participated in the project, but did not fund the work.



Many of the genes that have a role in the breakdown of caffeine also metabolise certain medicines. So unravelling the genes could help scientists understand why some patients respond differently to their drugs than others, and so help doctors to personalise their treatments, Pirastu said.