Bitter taste perception

Whether certain bitter compounds taste intense or barely register comes from a combination of three changes in the TAS2R38 bitter-taste receptor, which sets the taster versus non-taster form. Reading all three together captures the trait better than any single one.

What this receptor does

TAS2R38 is a bitter taste receptor that responds to a specific chemical group found in phenylthiocarbamide, or PTC, and the related compound PROP, and in the glucosinolates of brassica vegetables such as broccoli, Brussels sprouts, cabbage and kale.

Three changes in the gene travel together as two main versions: a tasting form and a non-tasting form. This panel reads all three, which is why it can classify the taster and non-taster forms completely rather than approximately.

A classic of human genetics, discovered by accident

In 1931 a chemist named Arthur Fox spilled PTC powder in his laboratory and a colleague complained about the bitter taste while Fox tasted nothing. The trait became one of the first human polymorphisms studied systematically, and PTC paper strips were a staple of school biology for decades.

Roughly a quarter to a third of people of European ancestry carry two non-tasting copies, with the proportion varying substantially between populations.

Why supertaster is a different concept

The popular term supertaster is often attached to this gene, and that is not quite right. It was defined by response to PROP in laboratory testing and correlates with the density of fungiform papillae, the small structures on the tongue that carry taste buds, which is largely independent of TAS2R38 genotype.

So this panel tells you about one receptor, not about overall taste sensitivity. Someone can be a genetic taster with an ordinary tongue, or a non-taster who nonetheless finds many foods intense.

The vegetable question, honestly

The idea that non-tasters eat more vegetables is intuitive and the evidence for it is inconsistent. Some studies find modest associations between taster status and lower brassica intake, others find nothing, and cooking method, culture, childhood exposure and repeated tasting all shift vegetable acceptance more reliably than genotype does.

Roasting rather than boiling, salt, fat and acid all reduce perceived bitterness, which is a more useful lever than a genotype for anyone trying to like sprouts.

What each TAS2R38 result means

Strong bitter taster. You carry mostly taster copies across the three TAS2R38 positions, so compounds in foods like raw broccoli, Brussels sprouts and tonic water taste sharply bitter to you. This can make certain vegetables less appealing, which is biology, not fussiness.

Bitter non-taster. You carry the non-taster form on both copies, so these particular bitter compounds register as little or no bitterness. Coffee, dark beer and raw cabbage-family vegetables probably taste milder to you than to most people.

Bitter taster. You carry at least one taster copy of the TAS2R38 receptor and detect these bitter compounds normally. This is the most common result and matches typical sensitivity to bitter vegetables and drinks.

Evidence & sources

This panel reads A49P (rs713598), V262A (rs1726866) and I296V (rs10246939).

Reads all three TAS2R38 changes that define the taster versus non-taster form, so this is a complete read of the main bitter-taste variant. Because of how this kind of test works, a few rare in-between forms cannot be reconstructed perfectly.

Common questions

Am I a supertaster? This panel cannot tell you. Supertaster status was defined by PROP response and tracks the density of taste papillae on the tongue, which is largely separate from this gene. TAS2R38 tells you about one bitter receptor.

Does this explain why I hate broccoli? Partly at most. The receptor responds to compounds in brassicas, but studies linking taster status to vegetable intake are inconsistent, and preparation and exposure matter more. Roasting rather than boiling genuinely reduces the bitterness.

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