Why Are Asians Disproportionately Affected by Asian Flush?
Recent findings may be able to shed some light on why Asians are most affected by the Asian flush condition. And it looks like the culprit is a simple staple food: rice!
The first cases of flushing in the face due to alcohol consumption were reported around 10,000 years ago. Coincidentally, around that exact time was when humans first began cultivating rice. Since the timelines match up and this was a widespread change in the human diet, scientists explored this connection further.
A team led by Bing Su, a geneticist at the Kunming Institute of Zoology in China and a professor at Yale University studied the genes of 2275 people from 38 different East-Asian populations, looking for a mutation that modifies the alcohol dehydrogenase enzyme we discussed earlier.
The gene mutation that Su and his 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 bloodstream, 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 (American Journal of Human Genetics, vol 65 p 795).
The mutation also causes a by-product of the alcohol’s metabolisation to accumulate in the body, which makes those who have the mutation flush red when they drink.
Here’s what Su and his team found in their studies:
- In certain areas of southeast China, nearly all of the subjects of the study suffered from Asian glow.
- In areas of western China, about two-thirds to three-quarters of people suffered from this reaction.
- Meanwhile, in northern areas of China where rice cultivation was less prevalent, far fewer people were afflicted.
In more scientific terms, from a scientific journal summary on Biomedcentral.com:
We studied a total of 38 populations (2,275 individuals) including Han Chinese, Tibetan and other ethnic populations across China. The geographic distribution of the ADH1B*47His allele[editors note: the "class I alcohol dehydrogenase sequence polymorphism (ADH1BArg47His)" mentioned here is another way to say 'enzyme deficiency' at the gene level] in these populations indicates a clear east-to-west cline, and it is dominant in south-eastern populations but rare in Tibetan populations. The molecular dating suggests that the emergence of the ADH1B*47His allele occurred about 10,000~7,000 years ago.
The researchers hypothesize that the cause of this adverse reaction to alcohol is a genetic mutation that was actually designed to protect early farmers from the potentially fatal effects of alcohol use. Interesting enough, at around the exact time that we began cultivating rice, we also realized that rice could be fermented to create an alcoholic beverage.
A mutation like this is actually quite common when it comes to 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 (fun fact: more than 65% of the worlds adult population actually suffers from lactose intolerance!).
The idea that this reaction has evolved to protect humans from alcohol use is further supported by the fact that it mirrors many of the symptoms of the drug disulfiram. Disulfiram, sold under the trade name Antabuse, is a drug designed to prevent relapse in alcoholics. If someone taking disulfiram consumes alcohol, they’ll encounter many of the same side effects that they’d experience if they were suffering from flushing from alcohol. Disulfiram actually works by inhibiting acetaldehyde dehydrogenase in the bloodstream, which increases the acetaldehyde in the body by almost tenfold... sound familiar?
So when it comes to the question of “why do I have Asian flush after consuming alcohol?” It's safe to say that rice being integrated into our diets thousands of years ago may be to blame!
What Are Treatments for Asian Flush? Is There a Cure?
Fortunately, if you suffer from this adverse reaction to alcohol, you don’t have to stop imbibing for posterity’s sake, or for health reasons.
The ingredients in Flyby boost glutathione levels, an antioxidant responsible for breaking down that pesky byproduct of alcohol, acetaldehyde (a fancy way of saying you won’t experience that embarassing blush).