New alcohol guidelines and East Asians
The new UK alcohol guidelines, the first full review since 1995, are predominantly focused on reducing the risk of cancer. This reasonable update is quite welcome news, given accumulated concrete scientific results on carcinogenicity of acetaldehyde, the first metabolite from alcohol . Probably, many other European people will be affected by these guidelines, and soon also people outside Europe. However, ‘no more than 14 units of alcohol a week’, toughened new drinking limits, is only for people with normal acetaldehyde-metabolizing capacity from intact aldehyde dehydrogenase 2 (ALDH2), and another heart protecting rule, ’around five units a week for women aged 55 or over’ is the same as well, actually both of which are true of the majority of western people .
Asians, particularly East Asians (Korean, Chinese, and Japanese), include significant numbers of the population with inactive ALDH2, approximately 30 to 40% of the whole population, which is encoded by the genotype—either homozygous (ALDH2⁎2/⁎2) or heterozygous (ALDH2⁎1/⁎2)—of the mutant ALDH2 allele (ALDH2⁎2), leading to significant loss of ALDH2 activity [3,4]. This point mutation in ALDH2 is the most frequent variant in humans and is present in 8% of the world’s population, or approximately 560 million people,  who show a distinctive physiological response to drinking even a very small amount of alcohol. This phenomenon includes facial flushing, nausea, palpitation, headache, pruritus, and a hangover the next morning, [4,5] which is predominantly caused by immediate and prolonged acetaldehyde exposure with an inherited deficiency of ALDH2 enzyme.
Though such bad experiences with alcohol have produced a lot of non-drinkers in East Asia, [4,5] however, a certain number of ALDH2 deficient people, despite immediate unpleasant symptoms, may continuously try to consume light to moderate alcohol for alleged beneficial health effect, definitely not the case for this population. In particular, East Asian cultural and social environment, in which the idea of group harmony is powerful and going out drinking after work with colleagues is an important element, forces this population to often face peer pressure for unwanted or scary drinking .
Thus, these stricter new guidelines are still ‘weak’ for a growing number of ALDH2 deficient people within western society, mostly ethnic East Asians, potentially giving some dangerous messages and no public protection against drinking pressure, and consequently requiring some modification.
Moreover, ALDH2 polymorphism has been indicated to be closely associated with digestive tract cancer, neurodegenerative disease, metabolic syndrome, and atherosclerotic vascular disease [2,4]. Currently, it may play an important role in the pathogenesis of myocardial infarction .
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Competing interests: No competing interests