Re: Alcoholic tolerance between different ethnic groups ?

Thanks for your question Lennart,

The rumor that you heard is basically correct; the populations of east Asia have high frequencies of a mutant version of the Aldehyde Dehydrogenase (ALDH) enzyme. This mutant version of the ALDH enzyme results in high levels the compound acetaldehyde, an intermediate in alcohol metabolism, which has toxic effects. In the body, ethyl alcohol (ethanol) is normally converted to acetaldehyde by either of the enzymes Alcohol Dehydrogenase (ADH) and Catalase. Acetaldehyde is then converted into acetate by ALDH. Low levels of acetaldehyde are enough to make your face turn bright red, and high levels are enough to make you quite ill. So, if you have a mutant version of the gene which codes for the ALDH enzyme, resulting in an enzyme that works slowly or not at all, you will be less likely to feel comfortable drinking alcolol because of the toxic effects of acetaldehyde.

For some interesting recent research on the connection between ALDH and alcoholism in Asian populations take a look at these articles:

Chen CC, Lu RB, Chen YC, Wang MF, Chang YC, Li TK, Yin SJ Interaction between the functional polymorphisms of the alcohol-metabolism genes in protection against alcoholism. American Journal of Human Genetics 1999 Sep; 65(3):795-807

Chen YC, Lu RB, Peng GS, Wang MF, Wang HK, Ko HC, Chang YC, Lu JJ, Li TK, Yin SJ Alcohol metabolism and cardiovascular response in an alcoholic patient homozygous for the ALDH2*2 variant gene allele. Alcohol Clinical Experimental Research 1999 Dec; 23(12):1853-60