Alcohol flush reaction (aka Asian glow) is caused by a buildup of acetaldehyde
This accumulation is usually caused by a polymorphism of (which leads to a deficiency of) ALDH2, which breaks down acetaldehyde; this deficiency is more prevalent in Asian people (more than 1/3)
One study examined 30 healthy Asian men from UCSD who were 21-25
The study had them drink certain amounts of alcohol and then measured their facial flushing at 30 minute intervals; it also assessed their level of intoxication using the Subjective High Assessment Scale which asks them to rate themselves on 11 items: uncomfortable, high, clumsy, muddled/confused, slurred speech, effects of alcohol, feelings of floating, dizzy, nauseated, drunk and activated
15 of the men were homozygous ALDH2*1, 14 were heterozygous and 1 was homozygous ALDH2*2; all the ones with ALDH2*2 were flushed
All the flushers had higher pulses and also responded more negatively to the questions of clumsiness, dizziness etc.
It’s possible that these intense reactions to alcohol could contribute to a reduced tendency among Asian people to drink excessively
However, many people who are deficient in the gene (esp. those who are heterozygous for ALDH2*1/2) have an increased risk for throat cancer; studies show that ALDH2 deficient people who have 2 beers per day have a 6-10 times higher risk of cancer than people who are not deficient