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Genetic science behind why 1 in 13 people literally cannot stomach alcohol
27th June, 2026 06:11 PM
Have you ever noticed someone’s face turning bright red after just a few sips of a drink?
Friends often laugh it off, teasing the person for getting tipsy too quickly. However, medical science reveals that this reaction is not a funny joke.
It’s a biological warning sign flashing straight from the liver.
When the liver cannot clear the poison
When a person drinks alcohol, the liver immediately goes to work to break it down. The first chemical it produces is a highly toxic substance called acetaldehyde.
Normally, an enzyme called aldehyde dehydrogenase 2, or ALDH2, quickly steps in to turn this poison into a harmless chemical.
For some people, however, a specific genetic variation changes everything. Their bodies produce a faulty version of this enzyme, meaning they cannot clear the toxic buildup.
While it is present across various regions worldwide, it is not distributed evenly. The variation is highly concentrated among people of East Asian descent, where between 36 per cent and 45 per cent of the population carry the altered gene.
However, medical researchers note that it also appears in smaller percentages among other groups, including African and Caucasian populations.
A review published in Aldehyde Dehydrogenase, Liver Disease and Cancer points out that this dysfunctional variant is actually “the single genetic polymorphism associated with the largest number of traits in humans.”
This means hundreds of millions of individuals globally are walking around with a completely different metabolic response to alcohol, making standard, population-wide health guidelines highly inaccurate for them.
The long-term danger general advice ignores
Global health guidelines often state that a specific number of drinks per day is safe or moderate. But these rules are just averages. They completely ignore the fact that human genetics create entirely different risk profiles.
What is considered a moderate weekend plan for one person could be highly toxic to someone whose face flushes.
Leaving that toxic acetaldehyde to linger in the body causes severe long-term damage. It acts as a dangerous carcinogen that attacks cells directly.
In a 2019 study published in the Journal of Hepatology, researchers discovered that “ALDH2 deficiency promotes alcohol-associated liver cancer” by triggering specific pathways that allow tumours to grow.
For people who experience this flush reaction, the risk of developing liver damage and oral cancers is exceptionally high, even with light drinking. Pay attention to how your body reacts to a glass.
That red face is not a sign of a good time; it is your genetics asking you to stop.
