Sunday 23 December 2018

Why do we love coffee when it is so bitter?


New findings show that people may be genetically predisposed to love the taste of certain beverages. Furthermore, this biological discovery could have far-reaching health consequences.
Evolution is thought to have favored people who were able to sense bitterness.
After all, sharp and unpleasant tastes can often come from toxic substances such as alkaloids that are present in poisonous plants.
But scientists have been confounded by the popularity of coffee for some time.
Coffee's bitter taste should theoretically elicit a negative response from people, and yet the drink is one of the most widely consumed beverages in the world.
The researchers behind a new study believe they may have found why humans enjoy drinking coffee, despite its bitterness.
Scientists from Northwestern University Feinberg School of Medicine in Chicago, IL, and QIMR Berghofer Medical Research Institute in Australia teamed up to examine the relationship between a person's genetic sensitivity to bitter substances, and the level of bitter beverages they consume.
How our taste works
"Taste has been studied for a long time, but we don't know the full mechanics of it," says Marilyn Cornelis, assistant professor of preventive medicine at Northwestern University. "Taste is one of the senses. We want to understand it from a biological standpoint."
The study by Cornelis and colleagues uses two sets of data, and they have published it in the journal Scientific Reports. The first dataset came from a large-scale study of Australian twins that showed a link between genetic variants and how people perceived different tastes.
Researchers highlighted specific variants they believed to be responsible for a higher perception of bitterness in three substances: caffeine, quinine, which is an ingredient in tonic water, and PROP, which is another bitter compound present in some vegetables.
The second dataset came from the UK Biobank, a research facility that stores blood, urine, and saliva samples from hundreds of thousands of people. The research team used more than 400,000 male and female samples along with self-reported answers from a questionnaire about beverage consumption.
The study used a natural experimental method called Mendelian randomization to compare variants in people's genes with how often the same people drank coffee, tea, and alcohol.
The definition of a heavy coffee drinker was someone who drank more than 4 cups a day while heavy tea drinking was more than 5 daily cups. Heavy alcohol drinkers were deemed to be those who drank more than three or four times each week.



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