Student writer: Hannah Ericson
Student editors:Rita Chakrabarti
23andMe editor: Jennifer McCreight, Thao Do
Have you ever wondered how your unique genetic variants affect how you taste certain foods, or how those foods affect your body? Have you noticed how something tastes a certain way to one person, but tastes drastically different to another?
A fun way to explore these differences in taste is by throwing a genetics potluck. This event is a great way to introduce people to the world of genetics and compare how taste perception can vary between individuals. Simply gather some of the foods mentioned in this article, invite some friends over, and dig in!
Bitter Taste Perception 
In 1931, scientist Arthur Fox was preparing the synthetic chemical phenylthiocarbamide (PTC) in his lab when he noticed something peculiar: As particles of PTC dust flew into the air, one of Fox’s co-workers noticed the dust had a very bitter taste, while he personally didn’t taste anything [6]. After further testing, Fox discovered that people tasted PTC as either very bitter, slightly bitter, or not bitter.
In 2003 — over seventy years after that fortuitous day in Fox’s lab — the TAS2R38 gene was discovered and helped solve the mystery surrounding the differences in bitter taste perception [6]. TAS2R38 controls the shape of a taste receptor on a person’s tongue. Variations in this gene determine how people taste the bitterness associated with PTC [6].
TAS2R38 has two alleles (different forms of the same gene). People with two copies of the same alleles are considered to be homozygous for TAS2R38 and either taste bitterness very strongly, or not at all. People with one of each of the two alleles, considered heterozygous for this trait, taste bitterness moderately [6].
Interestingly, other factors also influence one’s ability to taste PTC, such as age and gender. A person’s ability to taste PTC as bitter diminishes with age, and women are more likely to taste bitterness compared to men [6].
While people might not be able to whip up a batch of PTC at home, the same taste receptor can be activated by eating broccoli, which can have a bitter taste depending on your TAS2R38 alleles [2]. To explore how people’s bitter taste receptors vary, serve up some broccoli and see what happens.
Cilantro, with a bitter or soapy aftertaste
Cilantro is another food whose taste is affected by personal genetics. Some people enjoy the taste of cilantro, while others taste it as bitter or soapy. In 2012, 23andMe discovered that certain variants of the OR6A2 gene correlates with how people taste cilantro [4]. People with certain variants of the gene would taste it as bitter, while people with other variants didn’t. While at least three other genes are involved in the taste perception of cilantro, OR6A2 is the primary gene being studied [4].
Research has shown that OR6A2, which controls the shape of an olfactory receptor in the nose, is linked to the ability to smell aldehydes, organic chemical compounds that often have a soapy, sweet, or pungent scent, similar to the ones found in cilantro [4]. Scientist believe that people with certain versions of the gene are able to smell the aldehydes in cilantro, which affects how people taste the herb [1]. Research has shown that people with heritage from regions where cilantro is not commonly used in cooking, such as Europe, are more likely to perceive a bitter taste [4].
What do your guests taste when they eat cilantro? Set out a taco bar (make sure to include cilantro as an option), and let your guests find out for themselves.
The Scent of Asparagus
Did you know that a certain percentage of the population can smell asparagus when they pee? Benjamin Franklin even mentioned this phenomena in a letter to the Royal Academy of Brussels in 1781 [5]. Research led by Sarah Markt and Lorelei Mucci from the Harvard T.H. Chan School of Public Health found that 871 variants on chromosome 1 are linked to this phenomena [5]. Having different copies of these alleles affects whether or not a person is able to smell compounds made from metabolized asparagus when they pee. The researchers found that men were more likely to correctly identify the asparagus scent in urine compared to women [5].
To investigate whether you can detect the scent of asparagus in your urine, eat some asparagus, drink some water, and let nature take its course. See what happens when your potluck guests do the same.
Dairy Dilemmas 
Lactose intolerance occurs when a person’s body is unable to digest lactose, a sugar found in milk, which is commonly found in dairy products like cheese.
In early life, almost everyone is able to digest lactose, as it’s found in breast milk. However, over time, certain people lose their ability to produce the lactase enzyme, which breaks down lactose. This inability to break down lactose is what leads to the symptoms of lactose intolerance [3].
The LCT gene is responsible for producing the lactase enzyme [3]. In ancient times in a population in northern Europe, a mutation in this gene caused the lactase enzyme to persist into adulthood. This enabled people to begin using dairy as a staple of their diet [3].
Today, people who are able to digest lactose into adulthood are more likely to be of European descent, as this mutation was passed along through the generations [3]. Likewise, a higher percentage of people with Asian ancestry are lactose intolerant because this mutation wasn’t selected for in these populations and subsequently wasn’t passed down with as much frequency as in other areas of the world [3].
To avoid giving your guests stomach aches, survey them to see if anyone is lactose intolerant. If someone is, make sure you have some delicious dairy-free products on hand that can be served alongside a dairy-containing cheese plate or ice cream sundae bar.
Caffeine Sensitivity
Some people consider coffee a necessary part of their morning routine, while others avoid it all together. Variations in the CYP1A2 gene have been correlated with whether or not a person consumes a lot, or only a little, caffeine [7].
CYP1A2 codes for an enzyme that controls how fast our bodies break down caffeine. There are two alleles of this gene, a “fast” variant and a “slow” variant [7].
People who contain two “fast” variants in their genome metabolize caffeine nearly four times faster than people who have one or more of the “slow” variants of the gene. People with “fast” variants tend to experience a fast spike in wakefulness after drinking caffeine, which is later followed by a sharp decline in energy, while people with “slow” variants experience a slow and steady increase in wakefulness as the caffeine is metabolize [7].
Where do you and your potluck guests fall on the spectrum of caffeine sensitivity? Make a pot of coffee and see if your guests feel a sharp or subtle increase in wakefulness.
If You’re 21 and Older
Many people with Asian heritage may find that whenever they drink alcohol, their face turns red, they feel like they’re having heart palpitations, and they feel nauseous. This is called the “alcohol flush reaction,” and it is influenced by genetics. Alcohol flush reaction is caused by a variation in some people’s genome, which causes the enzyme aldehyde dehydrogenase (ALDH) to be less functional [8]. Normally, ALDH breaks down acetaldehyde, but in people who demonstrate the flush reaction, the ALDH enzyme doesn’t break down the acetaldehyde found in alcohol. This results is the buildup of acetaldehyde in that person’s body, causing the symptoms characteristic of the flush reaction [8].
Hopefully, this article will inspire you to prepare dishes with broccoli, asparagus, cilantro and dairy products to serve alongside some caffeinated beverages or alcohol, age permitting. Exploring differences in taste perception, caffeine and lactose sensitivity, and alcohol flush is a fun and easy way to learn more about genetics, your potluck guests, and yourself.
- Doucleff M. (2012, September 14). Love To Hate Cilantro? It’s In Your Genes And Maybe, In Your Head. NPR.org. https://www.npr.org/sections/thesalt/2012/09/14/161057954/love-to-hate-cilantro-its-in-your-genes-and-maybe-in-your-head
- Gholipour, B. (2013, September 11). The Broccoli Problem: Why Some People Taste Things More Bitter. Live Science. https://www.livescience.com/39578-why-some-hate-broccoli-html
- Mattar, R., de Campos Mazo, D. F., & Carrilho, F. J. (2010). Lactose intolerance: diagnosis, genetic, and clinical factors. Clinical and Experimental Gastroenterology, 5, 113-121.
- SciShow. (2015). Retrieved January 12, 2018, from https://www.youtube.com/watch?time_continue=103&v=6ymoPRWxZl8
- Shields, J. (2016, December 14). If You Can Smell Asparagus in Urine, Thank Your Genetics. HowStuffWorks. https://science.howstuffworks.com/life/genetic/asparagus-urine-smell-detection-genetic-dna.htm
- Woodling, S. (2006). Phenylthiocarbamide: A 75-Year Adventure in Genetics and Natural Selection. Genetics, 172, 2015-2023.
- Yang, A., Palmer, A. A., & de Wit, H. (2010). Genetics of caffeine consumption and responses to caffeine. Psychopharmacology, 211(3), 245-257.
- Ye, L. (2009). Alcohol and the Asian flush reaction. SURG Journal, 2(2), 34-39.