Whether you prefer drinking tea or coffee may come down to your genes.

Tea and coffee contain bitter components that contribute to their pleasant taste. Both drinks contain bitter-tasting caffeine, while coffee contains another bitter molecule called quinine, which is also found in tonic water.

Previous research has found that people taste bitter flavours like caffeine, quinine and an artificial substance called propylthiouracil differently according to the types of taste receptor genes they have.

To find out if this variation influences preference for tea or coffee, Daniel Hwang at the University of Queensland in Australia and his colleagues studied the relationship between taste receptor genes and tea and coffee consumption in over 430,000 men and women aged 37 to 73 in the UK.

Super-tasters

The participants with gene variants that made them taste caffeine more strongly were 20 per cent more likely than the average person to be heavy coffee drinkers, meaning they drank more than 4 cups per day.

At the same time, these caffeine “super-tasters” were less likely to drink tea, says Hwang. This may be because people who are better at detecting caffeine are more prone to becoming addicted to its stimulant effects, and coffee contains more caffeine than tea. “But future studies are needed to investigate this,” says Hwang.

In contrast, participants with gene variants that made them more sensitive to the tastes of quinine and propylthiouracil were 4 and 9 per cent more likely than the average person to be heavy tea drinkers respectively, meaning they drank more than 5 cups per day. They were also less likely to drink coffee.

It’s unclear why this is the case, but it may be because super-tasters of quinine and propylthiouracil – which are both more bitter than caffeine – are more sensitive to bitter tastes overall. As a result, they may find the intense bitterness of coffee overwhelming and prefer the gentler bitterness of tea, Hwang says.

Journal reference: Scientific Reports , DOI: 10.1038/s41598-018-34713-z