Recent scientific research has showed that eight genes have an overwhelming influence on how our bodies individually react to caffeine. The studies, led by Marilyn Cornelis, a research associate at the Harvard T.H. Chan School of Public Health, found that the eight genes related to the metabolism of caffeine and its psychoactive effects on the brain, as well as lipid and glucose metabolism, but their role in coffee consumption is not fully clear yet.
These startling discoveries show why caffeine affects people differently and how caffeine influences coffee-drinking behaviour. For example, some people may feel energized on a daily cup of coffee, whilst others might need even four cups to feel the same effect. As a result, if the one-cup-a-day person consumes four cups, he or she might feel incredibly jittery or experience digestive issues, discouraging that level of consumption going forward.
There are also people who simply cannot drink caffeine since it’s simply too powerful for the makeup of their genes. The analysis involved searching for consumption patterns and single “letter” changes in the genetic code called single-nucleotide polymorphisms, or SNPs. The study’s senior author, Daniel Chasman, a professor of medicine at Harvard Medical School and the Harvard-affiliated Brigham and Women’s Hospital, said in a statement that the work is an example of how genetics can influence habitual behaviour.
One huge caveat: the new genes explain about 1.3 percent of our coffee-drinking behaviour, which is similar to that reported for other habitual behaviour, such as smoking and alcohol consumption. Culture is a probably sizable influence, researchers said, but there’s also a strong chance that additional genes remain to be found - perhaps many more. The genes found so far might represent only the tip of the coffee iceberg on coffee consumption, since coffee is rich in active compounds in addition to caffeine, some of which may also have physiological effects.
The researchers joined forces and recruited additional investigators, with each team contributing DNA samples and data sets, including detailed information of the coffee-drinking habits of 120,000 people of European and African-American ancestry. The current study was launched by the international Coffee and Caffeine Genetics Consortium, which was launched two years ago by investigators who had published parallel work on caffeine-related genes.
The next question is for researchers is - who benefits – and doesn’t benefit - most from coffee? If, for example, caffeine is protective, some individuals might have very similar physiological exposure to caffeine, once you balance the metabolism. But if coffee has other potentially protective constituents, those levels are going to be higher if you consume more cups, so they might actually be benefitting from non-caffeine components of coffee. So it’s a little bit complex than meets the eye, but one thing’s for sure: how a lot of our daily lives pan out are all in the genes…!