When it comes to pinpointing the precise cause of Asian flush, it is necessary to take many factors into consideration. This is because, whilst the underlying cause is genetic, people don’t experience any flushing symptoms without the introduction of alcohol.
In this regard, it is important to recognize that Asian flush is as a reaction to a condition, rather than a condition in itself. Moreover, the severity of this reaction is highly dependent on what kind of alcohol is introduced into the system, the rate at which it is introduced, along with one’s own internal physical state at the time the alcohol is being metabolized.
Genetic Predisposition to Acetaldehyde Build-up
The root cause is a genetic predisposition to acetaldehyde build-up that is most commonly observed in people of Asian decent, hence it being colloquially termed “Asian flush” despite it not being exclusive to Asians.
Acetaldehyde is a toxic by-product of alcohol metabolism that is usually broken down by enzymes in our body in order to stop it from accumulating and causing a toxic reaction – i.e. the various symptoms of Asian flush. All that is required is one of more specific gene variants to be present for acetaldehyde build-up to occur.
One gene variant, observable in approximately 50% of Asian people, is called the mitochondrial ALDH2 allele, which results in a deficient aldehyde dehydrogenase enzyme that works at about 10% of its usual capacity. This enzyme is normally responsible for preventing acetaldehyde build up by catalyzing its conversion into non-toxic acetic acid.
In addition to this, and contrary to common belief, a study confirmed that 80% of Asians and nearly all Japanese, Chinese and Koreans have multiple variations in the gene coding for the alcohol dehydrogenase enzyme that causes them to metabolize alcohol twice as fast as their non-Asian counterparts. This results in a metabolic process that converts alcohol into toxic acetaldehyde at a much faster rate than usual.
A combination of these gene variants or either one on its own is enough to result in abnormal levels of acetaldehyde build-up when alcohol is consumed. That said, without the introduction of alcohol, someone with these gene variations will not exhibit any of their symptoms.
As mentioned above, the genetic predisposition to acetaldehyde build-up only becomes a problem when the body is required to metabolize alcohol. Therefore, when trying to ascertain the cause of Asian flush it is important not to neglect the other half of the equation.
For example, the rate at which alcohol is consumed has a large effect on levels of acetaldehyde build-up and in turn the severity of one’s reaction. This is because, whilst the aforementioned genetic predispositions render enzymes deficient in breaking down acetaldehyde and over efficient in producing it, these are merely variations in efficiency. This means that by reducing the alcohol load on the metabolic system one can still rely on these enzymes performing their intended function only at a slower and more manageable rate.
In addition to the rate of consumption, the type and composition of alcohol consumed can drastically affect the severity of one’s reaction. This is because alcohol is rarely delivered to the body in pure form, rather via a variety of brewing methods and mixed concoctions that contain other ingredients that can significantly affect the metabolic process and accelerate the production of acetaldehyde.