A team of researchers, including one from The University of Western Australia, has found there may be some truth in the slogan: "Coffee: If you're not shaking, you need another cup." They've identified the genes that determine just how much satisfaction you can get from caffeine.
The results could also help to explain why coffee, which is a major dietary source of caffeine and among the most widely consumed beverages in the world, is implicated in a range of health conditions.
Six new regions of DNA (loci) associated with coffee drinking behaviour are reported in the study published in Molecular Psychiatry.
The findings support the role of caffeine in promoting regular coffee consumption and may point to the molecular mechanisms that underlie why caffeine has different effects on different people.
The researchers included Dr Jennie Hui, the Director of the Busselton Health Study Laboratory and Adjunct Senior Research Fellow in UWA's School of Population Health.
The study was led by Marilyn Cornelis, a Postdoctoral Fellow at Harvard University, and colleagues who conducted a genome-wide association study of coffee consumption for 120,000 people of European and African-American ancestry.
"The findings highlight the properties of caffeine that give some of us the genetic propensity to consume coffee," Dr Hui said.
"Some of the gene regions determine the amount of coffee that makes individuals feel they are satisfied psychologically and others physiologically. What this tells us is that there may be molecular mechanism at work behind the different health and pharmacological effects of coffee and its constituents."
The authors of the study identified two loci, near genes BDNF and SLC6A4, that potentially reduce the level of satisfaction that we get from caffeine which may in turn lead to increased consumption.
Other regions near the genes POR and ABCG2 are involved in promoting the metabolism of caffeine.
The authors also identified loci in GCKR and near MLXIPL, genes involved in metabolism but not previously linked to either metabolism or a behavioural trait, such as coffee drinking.
The authors suggest that variations in GCKR may impact the glucose-sensing process of the brain, which may in turn influence responses to caffeine or some other component of coffee.
However, further studies are required to determine the effects of these two loci on coffee drinking behaviour.
The Busselton Health Study (BHS) is one of the world's longest running epidemiological research programs. Since 1966, it has contributed to an understanding of many common diseases and health conditions. The unique BHS database is compiled and managed by UWA's School of Population Health.
Dr Jennie Hui (UWA School of Population Health and School of Pathology and Laboratory Medicine) (+61 8) 9346 1931
Adjunct Professor John Beilby (UWA School of Pathology and Laboratory Medicine) (+61 8) 9346 2368
Tony Malkovic (UWA Public Affairs) (+61 8) 6488 3229 / (+61 4) 11 103 398