Asian glow & oesophageal cancer

Does your face go red after a glass of wine or beer? If the answer is yes, then you have the so-called alcohol flushing response, also known as ‘Asian glow’ or ‘Asian flush’. This characteristic physiological response to drinking alcohol includes facial flushing, nausea and tachycardia and is seen in approximately 36% of East Asians (Japanese, Koreans and Chinese).  The response is due to an inherited deficiency in the enzyme aldehyde dehydrogenase 2 (ALDH2). Although most if not all of the East Asian public is aware of this alcohol flushing response, few realise that ALDH2-deficient individuals are at much higher risk of developing oesophageal cancer from alcohol consumption when compared to individuals with fully active ALDH2. It is estimated that there are at least 540 million ALDH2-deficient individuals worldwide and this represents about 8% of the world population.

Ethanol is first metabolised by alcohol dehydrogenase (ADH) into acetaldehyde, which is a mutagen and animal carcinogen. It causes DNA damage and has other cancer promoting effects. Acetaldehyde is then metabolized to acetate mainly by ALDH2. There are 2 main variants of ALDH2 in the East Asian population – the normal one (ALDH2 Glu/Glu ) with full activity and the abnormal one (ALDH2 Lys/Lys) with no activity at all. If you are a heterozygote, then you have a mixture of the two (ALDH2 Glu/Lys) and you have some ALDH2 activity.

In individuals with no ALDH2 activity, the accumulated acetaldehyde will cause intense facial flushing, nausea, tachycardia and histamine release which is so unpleasant that the individual is unable to consume any significant amount of alcohol. Thus, the individual is protected from the increased risk of oesophageal cancer from alcohol consumption. Heterozygotes have a low level of ALDH2 activity and so develop tolerance to acetaldehyde and the flushing response, thus, becoming regular heavy drinkers with the associated increased risk of developing oesophageal cancer. Studies in Taiwan and Japan have shown that alcohol consumption in ALDH2 heterozygotes increased their risk of oesophageal cancer by 3.7 to 18.1 times.

A simple but accurate way to determine if you are ALDH2 deficient is to answer yes or no to the following 2 questions: (1) Do you have a tendency to develop facial flushing immediately after drinking a glass (about 180 cc) of beer? (2) Did you have a tendency to develop facial flushing immediately after drinking a glass of beer in the first one or two years after you started drinking? If you answer yes to either question then you are considered ALDH2 deficient. ALDH2-deficient individuals should be warned about their increased risk of developing oesophageal cancer with alcohol consumption.

What would be the impact on oesophageal cancer risk if you, an ALDH2 heterozygote, went from a heavy (≥ 18 units / week) or moderate (9 – 17.9 units / week) drinker to a light (1 – 8.9 units / week) drinker? It has been calculated that 53% of oesophageal squamous cell carcinoma might be prevented in the Japanese male population if moderate or heavy drinking heterozygotes became light drinkers!

(If you wish to read about Asian glow in more detail, please go to www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.1000050)