Source: WiseGeek - Do People of Asian Descent Have Difficulty Metabolizing Alcohol?

Some people of Asian descent have noticed that they have difficulty handling alcohol, expressed by excessive facial redness, sweating, increased body temperature, and a higher heart rate after consuming a small amount of alcohol. This syndrome is called “Asian flush” and can be deeply embarrassing, especially if it arrives unexpectedly. This causes many people to think that people of Asian descent cannot process alcohol, although this is not strictly true. Asian flush can affect non-Asians as well, but the genetic mutation that causes it is much more common among people of Asian descent.

Some people of Asian descent have noticed that they have difficulty handling alcohol, expressed by excessive facial redness, sweating, increased body temperature, and a higher heart rate after consuming a small amount of alcohol. This syndrome is called “Asian flush” and can be deeply embarrassing, especially if it arrives unexpectedly. This causes many people to think that people of Asian descent cannot process alcohol, although this is not strictly true. The reaction can affect non-Asians as well, but the genetic mutation that causes it is much more common among people of Asian descent.
When most people consume alcohol, it is processed by two liver enzymes. The first, alcohol dehydrogenase, converts the alcohol to acetaldehyde. The second, aldehyde dehydrogenase, converts the acetaldehyde into acetic acid, which can then be broken down into carbon dioxide and water, which can be harmlessly expressed from the body. With excessive consumption, this process can take some time, as most college students have discovered, but the liver will eventually metabolize the alcohol.
Many people of Asian descent, however, have a genetic mutation that limits the formation of aldehyde dehydrogenase, resulting in a build up of acetaldehyde, which can be toxic in large quantities. The symptoms of Asian flush are indicators that the toxin has built up enough to cause the body to try to get rid of it through sweat or vomiting in extreme cases. If the problem sets in, alcohol consumption should be stopped for the evening to allow the body to metabolize what is already in the person's system.
Asian flush, like all alcohol tolerance issues, is to some extent genetic. It can also be affected by factors such as body type or whether or not food has been consumed with the meal. The condition also does not act in the same way for all people it affects. Some, for example, can drink several beers before suffering ill effects, while others can have only a small amount of alcohol before feeling ill. It is a good idea for all people to understand the limits of their body and not to exceed them.
There is evidence to suggest that some measures can be taken to decrease the effects of this problem. Consumption of sugars has been linked with an increased ability to metabolize alcohol. Sufferers might want to consider ordering drinks with a high fructose content or eating sweets shortly before drinking. It is also a good idea to avoid spicy foods and warm ambient temperatures, which will lead to flushing even without alcohol.