The Science Behind the "Asian Flush"
An intense red color on the cheeks, or even neck and shoulders, after downing alcoholic drinks is a sign that one’s body is not properly digesting the alcohol. This phenomenon, often referred to as the “Asian Flush” affects more than 50% of all East Asians. The reason why this occurs much more in East Asians than those of other ethnicities comes down to history, evolution and genetics.
To understand why and how this phenomenon occurs, we should first look at how alcohol is broken down in the body to begin with. Alcohol dehydrogenase, an enzyme in the body, converts alcohol into acetaldehyde. Acetaldehyde is then converted into smaller, harmless compounds by a second enzyme, acetaldehyde dehydrogenase (ALDH2).
Some East Asians have a genetic variance in ALDH2, in which this enzyme is inactive. This leaves acetaldehyde in the bloodstream for longer than usual, and a buildup of acetaldehyde triggers the release of histamine. Histamine causes blood vessels to dilate and the face to heat up and turn red. Beyond physical appearance, other symptoms include nausea, headaches, dizziness, red eyes and a rapid heartbeat. While these are perhaps what a hangover feels like, these symptoms are immediately noticeable and paired with intensely flushed skin. It is also important to note that as with other genetic conditions, individuals will be affected in various ways and with different severities.
The “Asian Flush” is estimated to have begun about 10,000 years ago in southern China. The importance of this time frame is that 10,000 years ago is when agriculture emerged, causing a massive shift in diet and lifestyle. It is suspected that this eventually led to a change in the genetic makeup of the Chinese population. With migration occurring over time, the inactive form of ALD2 has spread to the neighboring countries of South Korea and Japan.
This buildup of acetaldehyde comes with health risks. Having the “Asian Flush” is more than just being associated with low alcohol tolerance and perhaps joked about with friends. It can lead to severe and major health damage in the future, and should not be ignored. Acetaldehyde is considered to be more toxic than alcohol, especially as it is a known cancer-causing agent. In particular, it triggers inflammation in the upper gastrointestinal tract, causes DNA damage, and increases risk for gastrointestinal diseases such as stomach cancer, esophageal cancer and peptic ulcers. The research and statistics are shocking-- a person with this condition consuming two beers a day will be 10 times more at risk for developing esophageal cancer than an unaffected person.
The risk for developing cancer and gastrointestinal conditions is definitely not something to ignore for those who are affected. In fact, it is recommended that those affected should not binge drink and should limit or watch their alcohol consumption. As this is a genetic condition, there is no medication or cure for treating this. Other ways to cope would be to choose drinks with lower alcoholic content, not drinking on an empty stomach, and alternating with water and non-alcoholic beverages.
Although alcohol in moderation is considered to be good for the body, consumption should always be watched no matter if one has an affected ALDH2 or not. In particular, those with the inactive ALDH2 should be more careful when drinking, as there are many severe long-term consequences than just turning red in the moment.
References:
https://www.healthxchange.sg/food-nutrition/food-tips/asian-flush-alcohol-red-face
https://www.huffpost.com/entry/asian-flush-asian-glow-drinking_n_5aec65abe4b041fd2d25e9bd
https://www.nbcnews.com/healthmain/asian-flush-red-flag-risk-cancer-1C6437432
https://getsunset.com/blogs/news/why-your-face-turns-red-when-you-drink
https://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-10-15