Addicted to Coffee? Blame it on Your DNA

A new study reveals that people who can't get through the day without consuming more than two cups of coffee are missing a certain gene variant linked to the body's ability to break down caffeine.

The study, published in the journal Scientific Reports, showed that the gene, called PDSS2, can negatively regulate the expression of the caffeine metabolism gene, making caffeine stay longer in the body.

"The hypothesis is that people with higher levels of this gene are metabolizing caffeine slower, and that's why they're drinking less coffee," explained Nicola Pirastu, a Chancellor's Fellow at the University of Edinburgh's Usher Institute and author of the study, in a report from Time Magazine. "They need to drink it less often to still have the positive effects of caffeine, like being awake and feeling less tired."

For the study, the researchers analyzed the genetic makeup of 1,213 people from seven different villages in Italy. Each participant was then asked to complete a survey, which included a question about how many cups of coffee they drink on a daily basis.

The researchers discovered that participants who have lower expression of a certain variant of PDSS2 tend to drink more coffee compared to those who have greater expression of the gene. Researchers believe that PDSS2 slows down the metabolism of caffeine in the body, resulting to a longer and more enduring caffeine drive.

In a similar study involving 1,731 people in the Netherlands, the researchers were able to produce similar association between coffee consumption and PDSS2 gene. However, the apparent influence of the gene over consumption is relatively weaker in the second study.

National preferences for coffee might play a part in the different influence of PDSS2 in both countries. Italians prefer mocha and espresso, while people in the Netherlands prefer filtered coffee. While the caffeine content of the drinks may be the same, the Dutch are using a larger cup size that contains more caffeine overall.