Episode 7 ·MAPASGEN ·Free

Coffee,Wine, andCoriander:WhyYourTastesAreWritten inYourDNA

Episode 7 ·MAPASGEN ·FreeMaterial

Approximately one in seven people on the planet cannot stand coriander — for them it does not taste like a fragrant herb, it tastes like soap.This is not a preference and not upbringing.It is a variant of theOR6A2 gene, which encodes an olfactory receptor sensitive to aldehydes — the very molecules that give coriander its distinctive aroma.Carriers of a particular variant of this gene perceive those same aldehydes in a completely different way — and are entirely sincere in their inability to understand how anyone eats the stuff.

Coriander is just one of hundreds of examples of how genetics shapes taste preferences.Coffee, alcohol, bitterness, spice, sweetness — each of these sensations is underpinned by specific genes whose variants are unevenly distributed across the population.Your palate is not just habit.It is biochemistry.

Coffee:WhySomePeopleDrinkSixCups andSleepLikeBabies

Caffeine is metabolised in the liver by the enzymeCYP1A2, encoded by the gene of the same name.Its activity varies dramatically between individuals depending on the gene variant.

• Fast metabolisers (*1A variant): break down caffeine quickly.A cup of coffee produces a brief lift and clears rapidly.These people can drink coffee in the evening and fall asleep without difficulty.
• Slow metabolisers (*1F variant): caffeine lingers in the bloodstream considerably longer.A single afternoon cup can disrupt sleep.In slow metabolisers, consuming more than four cups of coffee a day is associated with an elevated risk of myocardial infarction — as shown in a large study of more than 4,000 participants published inJAMA in 2006.

A historical note: Honoré deBalzac reportedly drank up to 50 cups of very strong coffee a day — without it, he claimed, he could not write.He died at 51 of heart failure.Whether he was a slowCYP1A2 metaboliser, we cannot know.But his case illustrates how differently organisms handle the same substance.

Bitterness:Supertasters andThoseWhoNoticeNothing

TheTAS2R38 gene encodes a bitterness receptor.Its variants determine how intensely you perceive bitter compounds — in particularPTC (phenylthiocarbamide) andPROP, as well as many natural bitter flavours in broccoli,Brussels sprouts, grapefruit, and dark beer.

• Supertasters: approximately 25% of the population.Broccoli is an ordeal; dark beer is unbearably bitter.They tend to eat less fatty food (fat masks bitterness) and show a more varied taste profile overall.
• Non-tasters: another roughly 25%.They barely perceive bitterness.They can drink tonic water without flinching and eat dark chocolate as if it were milk chocolate.
• Medium sensitivity: the majority — around 50% — fall between these two extremes.

Alcohol:AsianFlush andBeyond

Alcohol is metabolised in two steps.First, the enzymeADH (alcohol dehydrogenase) converts ethanol into acetaldehyde.ThenALDH2 (aldehyde dehydrogenase) converts the toxic acetaldehyde into harmless acetate.

Approximately 36% ofEastAsian populations carry theALDH2*2 variant, in which the second enzyme barely functions.Acetaldehyde accumulates, causing facial flushing, elevated heart rate, and nausea.This 'Asian flush' is not an allergy to alcohol — it is a disruption of alcohol metabolism.

Importantly: carriers ofALDH2*2 who drink regularly have a significantly elevated risk of oesophageal cancer — precisely because of acetaldehyde accumulation, which is a known carcinogen.

—Continued inPROMaterial —

ThePRO material contains the test 'YourHedonisticProfile': 8 questions about your taste preferences with an explanation of the likely genetic variants behind each, and how to find these markers in your ownDNA test.

Premium contains a full longreid on spiciness: why capsaicin is pain rather than taste, how evolution made humans the only mammals that eat chilli peppers voluntarily, and what theTRPV1 gene says about your pain threshold.

MAPASGEN — the podcast about genetics that is already reshaping your life.

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