The supertaster gene TAS2R38: are you a bitter-taster?

A trait explainer · Updated August 2026

23andMe & raw DNA

Where "supertaster" comes from

The story starts with an accident. In the 1930s a chemist working with a bitter compound called PTC (phenylthiocarbamide) let some of it drift into the air — and a colleague nearby complained about the bitter taste while the chemist noticed nothing at all. That mismatch turned into one of the most durable experiments in taste science. Hand a group of people a paper strip soaked in PTC, or its milder relative PROP, and they sort themselves cleanly into camps: some find it overwhelmingly, mouth-puckeringly bitter, some find it mildly bitter, and some taste essentially nothing.

The people at the intense end came to be called supertasters; the ones who tasted little or nothing, non-tasters; and the crowd in between, plain tasters. It's worth being clear about what "supertaster" really means, because the word oversells itself. A supertaster isn't someone with a refined palate or better taste in food — it just means their perception of these particular bitter compounds is turned up loud. Sometimes that's a gift; often, at the dinner table, it's a nuisance.

The biology of bitter taste

To see why some mouths react so differently, it helps to know what bitterness is for. Your sense of bitter taste is essentially a chemical alarm system. Many naturally toxic plant compounds are bitter, so evolution wired the tongue with a whole family of bitter-taste receptors — around 25 different types in humans — each tuned to a different range of bitter molecules. When a matching compound lands on one of these receptors, the taste cell fires a signal that your brain reads as "bitter," a built-in nudge to be cautious about what you're eating.

TAS2R38 codes for one of those receptors. It sits on the surface of taste-receptor cells clustered in the taste buds across your tongue, and it's specialized to detect a specific chemical group — the thiourea compounds, which include PTC and PROP in the lab and a set of related molecules in real food. Crucially, some of those food molecules show up in cruciferous vegetables like broccoli, Brussels sprouts, cabbage, and kale, and in other bitter foods. So TAS2R38 isn't just a laboratory curiosity: it's an everyday receptor doing everyday work every time one of those foods reaches your tongue.

The reason the receptor behaves so differently from person to person comes down to a handful of tiny spelling changes in the gene — and, conveniently, those changes travel together in a predictable pattern.

Tasters, non-tasters, and the PAV/AVI haplotypes

TAS2R38's effect is driven mostly by three variants — three single-letter positions in the gene, known by their rsIDs: rs713598, rs1726866, and rs10246939. Each one changes a single amino acid in the finished receptor protein. Written out, those three amino-acid positions spell a short code, and two combinations dominate the human population:

• PAV — proline, alanine, valine. This is the taster form: the receptor folds into a shape that binds bitter thiourea compounds efficiently, so it fires strongly.
• AVI — alanine, valine, isoleucine. This is the non-taster form: the receptor binds those compounds poorly, so the bitter signal is weak or absent.

Because you inherit one copy of the gene from each parent, you end up with a pair of these haplotypes — and that pairing is what sorts people into the familiar groups:

This is a satisfying trait to reason about because the mechanism is so concrete: the letters in the gene change the shape of a receptor, and the shape of the receptor changes how loudly bitterness rings. A few rarer haplotypes (with names like AAV or PVI) exist too, which is part of why real-world results don't fall perfectly into three neat bins. But PAV and AVI account for the great majority of people, and the PAV/PAV to AVI/AVI spectrum captures most of the story.

Why the gene is strong but not the whole story

Here's the honest part, and it matters. TAS2R38 is one of the strongest single-gene predictors in all of taste genetics — knowing your genotype tells you a great deal about how you'll react to a PROP strip. But "supertaster" is a bigger idea than one gene, and TAS2R38 doesn't own the whole thing.

Papillae density. Look closely at your tongue and you'll see small bumps called fungiform papillae, each housing taste buds. People vary in how densely these are packed — and those with more of them tend to experience taste (and the rough, drying sensations that ride along with bitterness) more intensely across the board. Someone can carry the strong-tasting PAV/PAV genotype yet have a sparse papillae count, or carry a non-taster genotype yet have a dense one. The classic "supertaster" — the person who finds nearly everything too intense — usually combines both a taster genotype and a high papillae density. That's why researchers measure papillae separately from genotype: they're two different ingredients of the same experience.

Learning and exposure. As with most of taste, habit does real work. A child who grows up eating bitter greens, dark chocolate, strong coffee, or hoppy adult drinks gradually recalibrates — the brain learns that the bitter signal is safe, even rewarding, and dials down the alarm. Two people with identical TAS2R38 genotypes can land in very different places if one spent years acquiring a taste for bitterness and the other avoided it. Genes set the volume knob; experience keeps adjusting it.

Put those together and TAS2R38 is best understood as a strong-but-partial predictor: a confident clue about your baseline bitter sensitivity, not a full readout of whether you'll call yourself a supertaster.

What it means day to day

So what does carrying a taster genotype actually feel like at the table? In broad strokes:

• Coffee and cocoa. Black coffee, espresso, and very dark chocolate lean bitter, and strong tasters often reach for milk, sugar, or a lighter roast. If you've never understood how anyone drinks espresso neat, your genotype might be part of the reason.
• Cruciferous vegetables. Broccoli, Brussels sprouts, cabbage, kale, and turnips carry compounds in TAS2R38's wheelhouse. To a strong taster they can read as harsh or sulfurous; to a non-taster, mild and pleasant.
• Grapefruit and bitter greens. Grapefruit, radicchio, endive, and rocket all have a bitter edge that hits tasters harder.
• Beer, gin, and other bitter drinks. Hop bitterness and botanical bitterness can feel bracing or overwhelming to strong tasters — one reason bitter drinks are so polarizing.

It's tempting to jump from there to "the supertaster gene decides your diet," and some studies do draw a modest link between bitter sensitivity and eating fewer bitter vegetables. But that link is small, inconsistent across studies, and easily swamped by everything else on the plate. Plenty of self-described supertasters happily eat their greens — they just roast them, salt them, add fat and acid, and cook the bitterness into something they love. Treat any "supertasters avoid vegetables" claim as a tendency in a population, not a rule about you. The gene nudges the odds; your kitchen has the final say.

If you enjoy this kind of thing, TAS2R38 has a natural companion in smell: the OR6A2 gene behind why cilantro tastes like soap to some people. Bitterness (a genuine taste) and the cilantro-soap effect (a smell) make a tidy pair — two different sensory systems, two different genes, both quietly shaping what you love or loathe.

How to look it up in your raw DNA

The genuinely fun part is that you can check TAS2R38 yourself, because its three defining SNPs — rs713598, rs1726866, and rs10246939 — are well-known positions that consumer DNA tests frequently include. If you've done a test like 23andMe or AncestryDNA, those markers may already be sitting in the raw data file you can download from your account.

You don't need to upload that file anywhere to read it. Quanome's DNA explorer reads your raw data right on your device, with nothing sent to a server — you look up a marker, and the file never leaves your hands. If you've never opened your raw data before, our 23andMe raw data guide walks through what's actually inside the file, and our companion piece on how to read 23andMe raw data without uploading it covers why on-device matters for something as personal as your genome. Caffeine fans might also enjoy looking up CYP1A2, the gene behind fast and slow caffeine metabolism, while they're in there.

One caveat worth keeping in mind: because there are three SNPs and a couple of rarer haplotypes, reading TAS2R38 is slightly more involved than a clean one-letter trait. Any single marker gives you a partial picture; the taster/non-taster call comes from the combination. And remember the bigger point — your genotype is a strong clue about your bitter baseline, but papillae density and a lifetime of eating fill in the rest.

Tendencies, not destiny

Here's the reassuring summary, and it's worth repeating: taste genes load the dice, they don't decide the game. TAS2R38 is one of the most powerful single markers in taste genetics, and knowing your genotype tells you, with unusual confidence, which way your bitter sensitivity leans. But "supertaster" is a blend of that gene, the anatomy of your tongue, and everything you've ever eaten — and people move along that spectrum throughout their lives as they acquire tastes they once found harsh.

So if you're a strong taster who's always found coffee and broccoli punishing, now you know part of the reason — and you also know it's not a life sentence. And if you carry two taster copies but adore your espresso and your kale, congratulations: you're living proof that the gene is only ever part of the story.

Educational only — this is a fun trait explainer, not medical, dietary, or diagnostic advice. Your DNA describes tendencies, not certainties, and it can't tell you what you're allowed to enjoy. For any health or nutrition questions, talk to a qualified professional.

Curious whether you carry the supertaster gene?

Quanome reads your raw DNA on your device and surfaces fun, well-studied markers like TAS2R38 — without uploading your genome. Learn more about Quanome →

Frequently asked questions

What is a supertaster?

A supertaster is someone who perceives certain bitter compounds much more intensely than average. The term originally came from taste-strip experiments with harmless chemicals called PTC and PROP: supertasters found them overwhelmingly bitter, while non-tasters barely noticed them. It's a tendency, not a medical category, and it's shaped by both genetics and the anatomy of your tongue.

What gene makes you a supertaster?

The main gene is TAS2R38, which codes for a bitter-taste receptor. Its PAV haplotype is the strong-tasting version and its AVI haplotype is the non-tasting one. Carrying two PAV copies leans you toward supertasting, though papillae density on your tongue and lifelong exposure matter too — so TAS2R38 is a strong-but-partial predictor, not the whole answer.

How do I know if I'm a supertaster?

The classic test uses a PROP or PTC taste strip: intense bitterness suggests supertasting, little or none suggests a non-taster. Everyday clues include finding black coffee, raw broccoli, grapefruit, or hoppy beer harsher than most people do. Your TAS2R38 genotype adds a genetic clue, but no single check is definitive — perception is the combination of all of them.

Can I check TAS2R38 in my 23andMe raw data?

Often yes. The three defining SNPs — rs713598, rs1726866, and rs10246939 — are well-known positions that frequently appear in consumer raw data files. A tool like Quanome's DNA explorer can read those markers on your own device without uploading your genome. Whether all three are present depends on the chip version your test used.

Do supertasters taste more bitter?

Yes, that's essentially the definition. Supertasters perceive the specific bitter compounds TAS2R38 detects — and often bitterness more broadly — more intensely than average tasters or non-tasters. This can extend to cruciferous vegetables, coffee, grapefruit, and some alcoholic drinks, though the size of the effect varies a lot from person to person.

Is being a supertaster genetic?

Partly. TAS2R38 genotype is a major, well-established driver of bitter sensitivity, so there's a real genetic component. But supertasting also depends on the density of fungiform papillae on your tongue and on learned exposure, so genes set a strong tendency rather than a fixed verdict. This is educational, not medical advice.

Does the supertaster gene affect what vegetables I like?

Some studies draw a modest link between bitter sensitivity and vegetable preference, since cruciferous vegetables like broccoli and Brussels sprouts carry compounds TAS2R38 detects. But the association is small and inconsistent, and plenty of supertasters love their greens — they just cook them boldly. It's a nudge in the data, not a rule about your diet.

Are PTC and PROP safe to taste?

The taste-test papers on which they're used are made with tiny, food-safe amounts and have been used in research and classrooms for decades. That said, the strips are a research and teaching tool, not something to seek out casually. This article is for curiosity and education, not a how-to.

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