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We Really Shouldn’t Love Coffee, But Still We Love It, Why?

Ever wonder why we love the bitter taste of coffee? According to a new study in Northwestern University, scientists said the more sensitive people are to the bitter taste of caffeine, the more coffee they drink. The sensitivity is based on genetics. Bitterness is a natural warning system to protect us from consuming harmful substances1. According to a survey, 64% of Americans over the age of 18 cosume atleast one cup of coffee daily.

Marilyn Cornelis one of the authors said about the study:

“You’d expect that people who are particularly sensitive to the bitter taste of caffeine would drink less coffee. The opposite results of our study suggest coffee consumers acquire a taste or an ability to detect caffeine due to the learned positive reinforcement (i.e. stimulation) elicited by caffeine.”

Researchers aimed to study the causal relationship between bitter taste perception and the consumption of coffee, tea and alcohol through a Mendelian randomization framework (MR), a technique commonly used in disease epidemiology. They used confirmed genetic markers for the perception of PROP, quinine and caffeine separately as genetic proxies for bitter taste perception and test their associations with the consumption of coffee, tea and alcohol among more than 400,000 participants in the UK Biobank cohort2.

It was noted that people who were more sensitive to caffeine and were drinking a lot of coffee consumed low amounts of tea. But that could just be because they were too busy drinking coffee. Those people avoided coffee that was sensitive to the bitter flavors of quinine and of PROP (a synthetic taste related to the compounds in cruciferous vegetables). As for alcohol a higher sensitivity to the bitterness of PROP was resulted in lower alcohol consumption, chiefly of red wine3-4.

It was also found that our perception of bitter tastes is informed by our genetics which contributes to the preference for coffee, tea and alcohol. It is also found that inherited factors play a key role in the amount of coffee or tea a person drinks in a day. The genetic variants linked to caffeine, quinine and PROP perception were previously identified through genome-wide analysis of solution taste-ratings collected from Australian twins. These genetic variants were then tested for associations with self-reported consumption of coffee, tea and alcohol in this study.

Conclusively Cornelis said:

“Taste has been studied for a long time, but we don’t know the full mechanics of it. Taste is one of the senses. We want to understand it from a biological standpoint.”

Given the popularity of these bitter beverages at a population level their consumption could have significant impact on health outcomes, but this requires further investigation.

Keywords: coffee, caffeine, bitter taste, taste buds, bitterness, taste perception, genetics, alcohol consumption, sensory neurons, stimulation, Mendelian randomization, disease epidemiology, framework, psychoactive drug, immune system.


  1. Ong. J., Hwang, D.L., et al., 2018. Understanding the role of bitter taste perception in coffee, tea and alcohol consumption through Mendelian randomization. Scientific Reports, 2018; 8 (1)
  2. Bycroft, C. et al. 2017 Genome-wide genetic data on ~500,000 UK Biobank participants. bioRxiv 166298,
  3. Reed, D. R. & Knaapila, A. 2010. Genetics of taste and smell: poisons and pleasures. Prog. Mol. Biol. Transl. Sci. 94, 213–240.
  4. Sadik , A., 2010. Orphanage Children in Ghana: Are Their Dietary Needs Met? Pakistan Journal of Nutrition, 9: 844-852.

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