Scientists have identified a gene variation that could influence the amount of caffeine a person consumes.
A study found that people with a variation in the gene PDSS2 tended to drink fewer cups of coffee than people without it. This gene and others have already been implicated in the regulation of caffeine metabolism by previous studies.
Study author Dr Nicola Pirastu of the University of Edinburgh said: 'The hypothesis is that people with higher levels of this gene are metabolising caffeine slower, and that's why they're drinking less coffee.'
'They need to drink it less often to still have the positive effects of caffeine, like being awake and feeling less tired.'
Researchers from the University of Trieste and the University of Edinburgh analysed the DNA of 370 people from a small village in southern Italy and 843 people from villages in north-east Italy. The participants were asked to complete a survey, which included a question about how many cups of coffee they drank each day. People with the variation on the PDSS2 gene tended to drink on average one fewer cup of coffee per day.
The results were compared with another study carried out in the Netherlands involving 1731 people. A similar effect was found, but the effect of the gene on coffee consumption was slightly lower. One theory to explain the change could be due to the different styles of coffee drunk in both countries, the researchers said. In Italy, people tend to drink smaller cups, such as espresso, whereas in the Netherlands the preference is towards larger cups which contain more caffeine overall.
The study, published in Scientific Reports, sheds new light on the biological mechanisms of caffeine metabolism, however further studies are needed to understand the full extent of the genetic link. 'We need to do larger studies to confirm the discovery and also to clarify the biological link between PDSS2 and coffee consumption,' said Dr Pirastu.