The TAS2R38 Bitter-Taste Gene: Why Some People Are "Supertasters" Who Find Broccoli and Coffee Extra Bitter

The 1-minute summary

• TAS2R38 is the gene that builds a bitter-taste receptor on your tongue, tuned to detect a family of compounds found in cruciferous vegetables like broccoli, kale, and Brussels sprouts.
• A handful of DNA differences in this gene sort people along a spectrum from "non-tasters" to "supertasters" who are highly sensitive to bitterness.
• Supertasters who say broccoli, coffee, or beer taste "too bitter" are describing a genuine difference in perception, not just picky eating.
• Studies have found an association between TAS2R38 genotype and vegetable preference, though the link is not always strong and many other factors are involved.
• Food preference is not set by genes alone. Repeated exposure and clever cooking really can change what you enjoy.

Hello. I want to walk you through a fun topic that many people experience without realizing there is a genetic explanation behind it. Why can one person take a single bite of broccoli and wince at the bitterness, while another eats it happily as if there were no bitter taste at all? Part of the answer is hidden in a gene called TAS2R38. Let me explain it in a simple way while keeping the science accurate.

What is TAS2R38 and how does it work?

Your tongue carries many kinds of taste receptors. The TAS2R38 gene builds one particular bitter receptor that is especially sensitive to two chemicals researchers use in the lab: PTC (phenylthiocarbamide) and PROP (6-n-propylthiouracil). These compounds are structurally similar to glucosinolates, substances found naturally in cruciferous vegetables such as broccoli, kale, Brussels sprouts, and mustard greens.

This was discovered by accident back in 1931, when a chemist released PTC dust into the air and noticed some colleagues complained it was bitter while he tasted nothing at all. That moment launched the study of bitter-taste perception as an inherited trait.

Why are some people "supertasters"?

The secret lies in just a few DNA differences (SNPs) in TAS2R38 that produce two main versions of the receptor protein, which scientists name after their amino acid sequence: PAV (the "taster" form that detects bitterness well) and AVI (the form that detects it poorly).

• People with the PAV/PAV genotype tend to be very sensitive to bitterness and are often called "supertasters."
• People with AVI/AVI usually detect little bitterness from these compounds and fall into the "non-taster" group.
• People with PAV/AVI (one version from each parent) sit in the middle with moderate sensitivity.

I should stress that the scientific meaning of "supertaster" is broader than TAS2R38 alone. It also involves the density of taste buds (fungiform papillae) on the tongue and other factors. Still, TAS2R38 is one of the clearest and most studied genetic pieces of the puzzle.

What does this have to do with liking vegetables and coffee?

A common question is whether being sensitive to bitterness means you will also hate vegetables. Several studies have found an association between TAS2R38 genotype and eating behavior, especially in children. Those who are bitter-sensitive tend to eat fewer bitter leafy greens, and some studies find they lean toward sweeter foods.

That said, I would read this carefully, because:

• In adults the link often weakens, because we learn to enjoy certain foods with repeated exposure (think coffee and beer, which almost nobody loves on the first sip).
• The bitterness of coffee and chocolate comes from different compounds than PTC/PROP, so TAS2R38 explains only part of the story. Humans have more than 25 kinds of bitter receptors.
• Culture, upbringing, and cooking methods have an enormous influence on preference.

If you are curious about how genetics shapes the flavors you perceive, take a look at our pieces on the gene that makes cilantro taste like soap and genetics and spice tolerance, two more examples of DNA shaping our eating experience.

What the science does NOT say

To be fair to the evidence, let me spell out the limits clearly.

• TAS2R38 does not lock in whether you love or hate vegetables. It only shifts a tendency. Genes are not destiny.
• Being a supertaster is not a better or worse tongue in any value sense. It is simply natural human genetic variation.
• Long-term health effects (for example, whether eating fewer vegetables raises disease risk) remain associations that need further study, not proven cause and effect.
• If you dislike vegetables, cooking them more skillfully, such as roasting, adding a little healthy fat, or pairing with sour and sweet flavors, genuinely reduces perceived bitterness. Taste can be trained.

แหล่งอ้างอิง (References)

1. MedlinePlus (NIH). TAS2R38 gene. medlineplus.gov
2. Kim UK, et al. Positional cloning of the human quantitative trait locus underlying taste sensitivity to phenylthiocarbamide. Science. 2003. pubmed.ncbi.nlm.nih.gov
3. Mennella JA, et al. Genetic and environmental determinants of bitter perception and sweet preferences. Pediatrics. 2005. pubmed.ncbi.nlm.nih.gov
4. Duffy VB, et al. Bitter receptor gene (TAS2R38), 6-n-propylthiouracil (PROP) bitterness and alcohol intake. 2004. pubmed.ncbi.nlm.nih.gov
5. Cleveland Clinic. Are You a Supertaster? health.clevelandclinic.org