Alcohol Flush Reaction - Why Drinking Alcohol Gives You a Red Face!
I built this whole website around trying to solve a problem that has plagued me personally my entire (adult) life: Alcohol flush reaction. Here I explain exactly what Alcohol flush syndrome is, where the condition comes from (genetically) and discuss some of the known side effects/additional health implications of flushing, mostly for those of Asian decent.
Fundamental Alcohol Flushing Facts
- Alcohol Flush Reaction is caused by a deficiency in the liver of an enzyme called aldehyde dehydrogenase (ALDH2); this disorder ultimately means that the liver cannot break down/metabolize acetaldehyde (alcohol).
- Alcohol flush syndrome has been slated to have some scary health implications: higher risks of esophageal cancer , hypertension & most recently discovered: even high blood pressure .
- There are cures for alcohol flush syndrome symptoms (I review a bunch of different Asian flush remedy products here) but there is not yet a solution for the underlying enzyme deficiency (not yet anyways, I have my fingers and toes crossed though!)
What Causes Alcohol Flush Reaction?
If you're like me and you turn bright red after in the face, neck area (and possibly other parts of your body, although it's only the upper torso for me) then you might have done what I used to do which is attributing the redness to slightly odd causes: healthy circulation, the body getting warm due to metabolism ('or something like that') or you might have guessed that you're allergic to alcohol. I know I did once I started getting really bloodshot and slightly dry eyes after alcohol.
Well, these are all valid guesses but as I later found out; none are correct. That 'tomato red mode' (plus all the other 'fun' symptoms) that only activates after drinking alcohol is predominantly due to an inherited deficiency in the enzyme aldehyde dehydrogenase 2 (ALDH2) .
Affecting something like 40% of people who drink alcohol and are of East Asian descent  (so Japanese, Chinese, and Koreans) - at least you can comfort yourself a litle knowing that you're one of many suffering from flushing.
So ultimately, the cause of alcohol flush reaction is genetic. It's not some sort of disease, however. It's sort of the opposite actually - a deficiency that gives rise to all the problems you associate with alcohol consumption.
And as mentioned, what is deficient is an enzyme called aldehyde dehydrogenase 2 (ALDH2). This enzyme is usually responsible for converting toxic acetaldehyde into relatively non-toxic acetate during the metabolic process as illustrated here :
Because of this deficiency, the consumption of alcohol by ALDH2 deficient individuals (as in those who suffer from alcohol flush reaction) leads to an accumulation of acetaldehyde in the body. It's this accumulation of a toxic substance that is causing the alcohol flush.
Alcohol Flush Reaction Symptoms
The most embarrassing symptom of alcohol flush reaction is a bright red face, usually accompanied by slight swelling around the flush-affected areas. 
Other symptoms include:
- Redness of face and upper body (i.e. the Asian flush)
- Swelling of the cheeks
- Red eyes
- Difficulty breathing
Could Rice Be Ultimately Responsible for Alcohol Flush Reaction?
This is a very recent discovery even for me: apparently rice is the root cause of alcohol flush! Who would have thought that a simple staple food would cause millions of people social annoyance and embarassment every time they took a sip of an alcoholic beverage?!
An article in New Scientist highlights studies performed by Bing Su, a geneticist at the Chinese Axcademy of Sciences in Kunming and colleagues where they studied the genes of 2275 people from 38 east-Asian populations, looking for the mutation that the gene that codes for the enzyme alcohol dehydrogenase.
The gene mutation that the team were looking for causes alcohol to be metabolised at 100 times the speed that it otherwise would be. As the enzyme removes alcohol so quickly from the blood stream, it protects people from the harmful effects of alcohol, and Su believes it confers an evolutionary advantage: a study in the Han Chinese suggests that those carrying the mutation have the lowest risk of alcoholism .
The researchers found that in certain areas of southeast China, nearly all of the subjects of the study suffered from alcohol flush/Asian glow. In areas of western China, about two-thirds to three-quarters of people suffered from the reaction, and in northern areas of China where rice cultivation was less prevalent, far fewer people were afflicted.
The researchers believed that the cause of this adverse reaction to alcohol is a genetic mutation that was designed to protect early farmers from the potentially fatal effects of alcohol use. At around the exact time that we began cultivating rice, we also realized that rice could be fermented to create an alcoholic drink.
A mutation like this is fairly common in human evolution: as humans began incorporating starch into their diets, the enzyme amylase evolved to process it more efficiently. The same goes for the enzyme lactase, which evolved to help us process lactose as we added dairy to our diets.
So if you're ever left thinking “why am I cursed with this alcohol flush reaction?” It seems that rice being integrated into our diets thousands of years ago may be the cause!
Asian flush syndrome increases risk of cancer?
In 1996, a Japanese study by Akira Yokoyama and his colleagues looked at the link between Asian flush and esophageal cancer - a type of cancer that is commonly seen in heavy alcohol consumers. They tested groups of alcoholic and non-alcoholic subjects who flush from alcohol and compared them to their respective control groups.
The results showed that the increased risk of esophagael cancer in subjects with Asian flush was “substantially higher” in both alcoholics and non-alcoholics as compared to their respective control groups. 
The results strongly suggest that because persons who have this mutant ALDH2*2 allele have a high concentration of blood acetaldehyde after drinking alcohol, acetaldehyde (a recognized animal carcinogen) plays a pivotal role in the pathogenesis of alcohol-related esophageal cancer in humans. These results suggest that to help lower their risk for esophageal cancer, persons with the ALDH2*2 allele should be encouraged to reduce their consumption of alcoholic beverages. 
Philip J. Brooks, Ph.D., of NIAAA's Laboratory of Neurogenetics, stated following his own research of the alcohol flush-cancer risk:
...the flushing response is a clinically useful biomarker of genetic susceptibility to esophageal cancer risk from alcohol.
Cancer of the esophagus is particularly deadly, with five-year survival rates ranging from 12 to 31 percent throughout the world. And we estimate that at least 540 million people have this alcohol-related increased risk for esophageal cancer.
Dr. Brooks and his colleagues explain that ALDH2 plays an important role in alcohol metabolism. When alcohol is consumed, it is first metabolized into acetaldehyde, a chemical similar to formaldehyde, which causes DNA damage and has other cancer-promoting effects.
East Asians have two main variants of the ALDH2 gene — one that produces an enzyme with normal activity, and another that results in an inactive enzyme. When individuals with the inactive variant drink alcohol, acetaldehyde accumulates in the body, resulting in facial flushing, nausea, and rapid heartbeat. For people with two copies of the inactive variant, these symptoms are so severe that they can drink very little alcohol. However, individuals with only one copy of the inactive variant can become tolerant to the unpleasant effects of acetaldehyde, which puts them at risk for alcohol-related esophageal cancer.
So, in short, due to the build up of the toxin acetaldehyde in their bodies of those who suffer from alcohol flush reaction, there might be a link between this toxin and the formation of alcohol related esophagael cancer.
And what's most scary, according to the Japanese study:
Notably, these studies showed that individuals with the inactive variant who drink the equivalent of 33 or more U.S. standard drinks per week have a 89-fold increased risk of esophageal cancer compared to non-drinkers.
Conditions that are similar to Asian flush
There are a number of skin/health conditions that have similar symptoms to alcohol flush reaction, but are different in their cause:
- Alcohol-induced respiratory reactions including rhinitis and exacerbations of asthma appear, in many cases, due to the direct actions of ethanol.
- Degreaser's flush
- Carcinoid syndrome
- Red ear syndrome
-  https://www.nih.gov/news-events/news-releases/alcohol-flush-signals-increased-cancer-risk-among-east-asians ↵
-  http://www.huffingtonpost.com/2013/11/21/facial-flushing-alcohol-high-blood-pressure_n_4312306.html ↵
-  http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1000050 ↵
-  https://www.researchgate.net/publication/266380484_Asian_Flushing_Genetic_and_Sociocultural_Factors_of_Alcoholism_Among_East_Asians ↵
-  https://pubs.niaaa.nih.gov/publications/arh294/266-273.htm ↵
-  https://getsunset.com/blogs/news/the-ultimate-guide-to-asian-flush-and-asian-glow/ ↵
-  http://www.cell.com/ajhg/abstract/S0002-9297(07)62333-7 ↵
-  https://getsunset.com/blogs/news/debunking-the-asian-flush-cancer-risk ↵
-  https://www.ncbi.nlm.nih.gov/pubmed/8850269/ ↵