Are you a tea or coffee person? The answer may lie in your genetic predisposition to bitter taste, researchers say.
It may be that bitterness acts as a natural warning system to protect us from harmful substances.
The study, led by researchers from the US-based Northwestern University and the QIMR Berghofer Medical Research Institute in Australia, examined reactions to three binary substances – caffeine, quinine and propylthiuracil (PROP) – to understand how they affect people's preference for drinking tea, coffee and alcohol.
The results showed that people who were more sensitive to caffeine and drank a lot of coffee consumed low amounts of tea.
In other words, people who have an increased ability to taste the bitterness of coffee – and especially the caffeine's distinctly bitter taste – learn to associate "good things with it".
"One could expect people who are particularly sensitive to the bitter taste of caffeine would drink less coffee," said Marilyn Cornelis, Assistant Professor of Preventative Medicine at the Northwestern University Feinberg School of Medicine.
"The opposite results of our study suggest that coffee consumers get a taste or ability to detect caffeine because of the learned positive stimulation induced by caffeine."
The study, published in the journal Scientific Reports, also found that people who are sensitive to the bitter tastes of kinin and of PROP – a synthetic flavor related to the compounds in cruciferous vegetables – avoid coffee.
For alcohol, a higher sensitivity to the bitterness of PROP resulted in lower alcohol consumption, especially of red wine.
"The findings suggest our perception of bitter taste, informed of our genetics, contributes to the preference for coffee, tea and alcohol," said Cornelis.
Researchers applied Mendel randomization – a technique commonly used in disease epidemiology – to test the causal link between bitter taste and beverage consumption in more than 4,00,000 men and women in Britain.