Tea or coffee? As in, which one do you prefer?Innocuous question, right? Yet earlier in history, as tea and coffee were first arriving to their shores, a European’s response might have reflected such weighty issues as:

• power (who had the means to bring tea and coffee to Europe)
• wealth and status (who could initially afford to purchase tea leaves and coffee beans)
• gender (e.g., men’s coffeehouses vs women’s social teas)
• politics (again, those coffeehouses vs social tea venues in which business—albeit of different types—was conducted)
• even citizenship (aside from East Frisia, Germany, for example, was slower to embrace tea)

Today, however, these factors aren’t really factors, and we assume our selection is simply a matter of personal preference, some liking tea more, others coffee.

However, according to a recent study by Jue-Sheng Ong and colleagues, this tea/coffee preference may instead be due to our individual genetic makeup!

The Real Question—Caffeine or PROP/Quinine?

Although most of us know about caffeine‘s bitterness, there are also two other bitter compounds at play here: propylthiouracil (PROP) and quinine.

Being able to taste bitterness has been a useful defense mechanism through most of human history, helping us avoid poisonous foods. This ability is even encoded in our genetic material—which allowed Ong’s team (2018) to use genetic markers for PROP, quinine, and caffeine perception as “genetic proxies for bitter taste perception and test their association with the consumption of coffee, tea and alcohol.”

Using genetics sidesteps the subjectivity of people rating their own perception of bitterness, although the participants did self report on how much tea, coffee, and alcohol they drank (only those whose consumption levels fell within the 20–80th percentile were included in this study). The study group comprised over 400,000 people, members of the UK Biobank.

The results?

The researchers detected a direct correlation between genetic markers and the subject’s beverage of choice:

• higher perceived intensity of PROP and quinine ⇒ tend to drink tea

• higher perceived intensity of caffeine ⇒ tend to drink coffee

The researchers note that while quinine is naturally found in coffee (PROP is not), an earlier study showed that “coffee drinkers tend to be less sensitive to quinine” (Ong et al. 2018), again supporting their preference for coffee.

Of course there are additional reasons for a person to choose coffee over tea:

caffeine . . . contributes to the perceived strength, body and bitterness of coffee, which has been related to its intake. It is possible that coffee consumers acquire a taste for (or an ability to detect) caffeine given the learned positive reinforcement (i.e. stimulation) elicited by caffeine. (Ong 2018)

Interestingly, no differences were found between males and females except that there was a stronger “association between caffeine perception and tea intake” (Ong 2018) in females.

So, tea or coffee? Your genes just might be driving your decision!

Source: “Understanding the role of bitter taste perception in coffee, tea and alcohol consumption through Mendelian randomization,” by Jue-Sheng Ong et al., Scientific Reports (November 15, 2018) 8:16414.