Stroke is the third leading cause of death in Taiwan, and the factors that can lead to stroke are numerous, including age, hypertension, diabetes, high blood lipids, heart disease, atrial fibrillation, smoking and so on. But a new study found that men who experience the so-called "Asian flush" are nearly twice as likely to have a stroke as the general population. The results of the study were published in the International Journal of medicine article titled "Stroke" in September.
The enzyme aldehyde dehydrogenase (ALDH2) plays a crucial role in human metabolism of alcohol, but people who easily become flushed even after only having one drink, may have the genetic mutation of this enzyme responsible for what is often referred to as the Asian flush or "Asian glow" response. Two alleles of ALDH2 -- ALDH2*1 and ALDH2*2 -- are genetic mutations that most often appear in populations of East Asian countries such as China, where about 35% of the population has the mutation, while 30% of Japanese and 20% of Koreans have the variant. Taiwan has the dubious distinction of having the highest Asian flush rate in the world at 47%.
Less than 5% of people of European descent exhibit a similar response to alcohol, and those who do generally do not carry the ALDH2 alleles associated with the Asian flush.
Three general studies have found that the two Asian alleles of the ALDH2 gene result in very different physical responses to the ingestion of alcohol. Those who carry the ALDH2*1 allele, may experience a mild blush, but little in the way of physical discomfort. However people with ALDH2*2 mutation will become flushed after consuming even small quantities of alcohol, of whom about 6% are completely unable to metabolize the acetaldehyde resulting from drinking. In addition to a deep reddening of the face, people in this second group may also experience palpitations, nausea, vomiting and other physical discomfort.
Individuals with the ALDH2*1 mutation have an increased risk of certain types of cancer, such as pancreatic and esophageal cancer. However, those with the ALDH*2 allele not only face a higher risk of cancer but also a 1.93 times higher risk of ischemic stroke. To avoid the threat of a stroke, persons who have this mutation of ALDH2 should completely avoid drinking alcohol and smoking, and should exercise regularly while maintaining a healthy diet.
The study also found it was primarily males with the ALDH2 gene mutation who had an increased risk of cancer and stroke, while females with either genetic mutation had almost no risk of stroke. The initial theory to explain this difference is that women secrete hormones that help better metabolize ethanol, thus reducing the risk of developing strokes.
Song Yuefeng, a physician in the Department of Neurology at Tri-Service General Hospital (National Defense Medical Center, Taiwan) said that at present the acetaldehyde dehydrogenase 2 gene can only be detected with a blood test. However, a simple way to test for the presence of the genetic mutation would be to see if a person experiences facial flushing and other telltale symptoms the very first time they drink a glass of beer or other form of alcohol.
Another option to test for this reaction would be to soak a lint pad in high-proof alcohol and then apply the pad to the inner surface of the upper arm for several minutes and then remove it. If the area of skin where the patch had been develops erythema (reddening) 10-15 minutes after it was removed, the person is deemed to have tested positive for the gene.
Dr. Song Yuefeng emphasized that not everyone who drinks alcohol and carries this gene will have a stroke. Taiwan has a deeply ingrained drinking culture and having one or two glasses of red wine a day can be good for cardiovascular health. Nevertheless, given the large percentage of people in Taiwan with this genetic variant, it's best to carefully manage one's consumption of alcohol.