A strong genetic link to coffee consumption has been found by scientists studying Italian villagers.
Coffee is one of the most consumed beverages worldwide and one of the primary sources of caffeine intake, but are some people slaves to their genes in this regard?
To find out, Edinburgh University's Nicola Pirastu and his colleagues carried out genetic analysis on over 1200 Italian coffee drinkers from villages in the south and northeast of the country. Alongside the genetic analysis, the study subjects also reported their average coffee intake.
The Edinburgh team used a technique called "genome-wide analysis" to screen the Italians' DNA for genetic signatures that cropped up repeatedly in the same place and tallied with their reported coffee intake. One DNA region came up red hot. It contains a gene called PDSS2, which switches off the production of enzymes in cells - and the liver especially - that break down caffeine.
People with very highly active forms of this gene, the team found, tended to report lower levels of coffee intake, because they metabolise caffeine more slowly. Conversely, individuals with lower levels of PDSS2 activity drink more coffee because their metabolic machinery dismantles caffeine far more rapidly, meaning that they crave their next wake-up hit sooner.
The team also verified their results using a second, larger group of 1731 Dutch coffee drinkers. The same trend broadly emerged, although the Dutch appeared to be significantly great slaves to caffeine, consuming three times as much coffee as the Italians, which Pirastu attributes to portion size.
"In Italy, moka or espresso are the preferred way of drinking coffee; in the Netherlands filtered coffee is preferred," he explains in his paper in Scientific Reports where the work is published.
Apart from being academically interesting, the results are also medically relevant. The same pathways that metabolise caffeine also help to break down certain drugs, so genetic insights of this sort can be helpful in comprehending how different patient groups will respond to certain classes of therapy.