Coffee or tea? The answer might be in your genes

Choice of drink linked to how we perceive bitterness of substances, researchers say

Man holding many tea and coffee cups
 People in the study who had a greater genetic predisposition to perceiving the bitterness of caffeine drank more coffee. Photograph: Getty Images

Do you prefer coffee or tea? The answer to that question might in part be down to your genes, research suggests.

Scientists say a genetic predisposition to perceiving the bitterness of particular substances appears to nudge us towards one beverage or the other.

Dr Marilyn Cornelis, co-author of the research from Northwestern University in Illinois, said: “The study adds to our understanding of factors determining beverage preferences – taste, in particular – and why, holding all other factors constant, we still see marked between-person differences in beverage preference as well as the amount we consume.”

The study, published in the Scientific Reports journal, involved two sets of data. The first was a large twin study which showed that, at least in those of European ancestry, particular genetic variants are linked to the strength of perception of different tastes: one specific variant was associated with slightly higher ratings of bitterness for caffeine, another to greater bitterness for quinine and a third to greater bitterness for a drug known as propylthiouracil, or prop.

The team then looked at data from another source: the UK Biobank, a research endeavour that recruited hundreds of thousands of participants aged 37 to 73 between 2006-10 and involved the collection of genetic data as well as health information, including answers to the question of how many cups of different drinks participants consumed each day.

Because our genes are fixed at conception, and our genetic variation can be thought of as random, they allow scientists to explore a sort of “natural experiment”, meaning they can look beyond many of the social or environmental factors that can muddy the waters of our hot drink habits.

The team found people with a greater genetic predisposition to perceiving the bitterness of caffeine drank a little more coffee, but an increased perception of the bitterness of quinine and prop were linked to a small reduction in coffee drinking.

The reverse patterns were seen when the team looked at the genetic variants and how much tea participants drank.

“While the effect of perception on your daily coffee intake might be relatively small – only a 0.15 cup per day increase – from a normal caffeine taster to a strong caffeine taster, it actually makes you 20% more likely to become a heavy drinker – drinking more than four cups per day,” said Jue Sheng Ong, first author of the research from QIMR Berghofer Medical Research Institute in Australia.

Tea being poured into cup
 Researchers said the findings for tea were harder to explain but might in part be down to heavy coffee drinkers tending to be very light tea drinkers. Photograph: Anthony Devlin/PA

The team also found that greater perception of the bitterness of prop was linked to a lower chance of being a heavy drinker of alcohol.

While the study has limitations, including that it relied on self-reporting of tea and coffee drinking, the team say it could help shed light on which cuppa we prefer.

“Given humans generally avoid bitter tastes, we interpret these findings as possibly a learned behaviour: if we can perceive caffeine well we associate this with the psychostimulant properties of caffeine and so seek more coffee,” said Cornelis.

Cornelis said the findings for tea were harder to explain, but might in part be down to heavy coffee drinkers tending to be very light tea drinkers.

Ong added the findings for tea might be down to tea containing lower concentrations of bitter substances, meaning it might prove more acceptable than coffee to those with heightened perception of bitterness.

“Our taste genes partially play a role in how much coffee, tea or alcohol we drink,” he said. “The preference towards tea can be seen as a consequence of abstaining from coffee, because our genes might have made coffee a little too bitter for our palates to handle.”

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