The history of beer and ALDH2

Smithsonian magazine has an interesting article on the history of beer this month.  See here. According to Patrick McGovern, an archaeologist at the University of Pennsylvannia, the earliest known alcoholic beverage comes from China:

Smithsonian: When McGovern traveled to China and discovered the oldest known alcohol—a heady blend of wild grapes, hawthorn, rice and honey that is now the basis for Dogfish Head’s Chateau Jiahu—he was touched but not entirely surprised to learn of another “first” unearthed at Jiahu, an ancient Yellow River Valley settlement: delicate flutes, made from the bones of the red-crowned crane, that are the world’s earliest-known, still playable musical instruments.

The interesting part about alcohol and distillation being first discovered in China is that about half of people of east Asian decent lack the gene to process alcohol, leading to what is nontechnically known as “Asian flush syndrome”.  When alcohol is consumed, it is first metabolized into acetaldehyde in the liver by the enzyme alcohol dehydrogenase.  The acetaldehyde is what makes you flush, gives you a headache, increase your heart rate and generally induces hangover-like symptoms.  Another group of enzymes converts the acetaldehyde to acetic acid, which can then be metabolized.  However, some Asians possess a variant of the  aldehyde dehydrogenase gene ALDH2, which renders it inactive.  So, they (including me) basically turn alcohol rapidly into a poison acetaldehyde that then persists.

It is well known that this ALDH2*2 variant is protective of alcoholism.  In fact, the drug used to treat alcoholism – disulfiram, blocks the conversion of acetaldehyde to acetic acid thereby mimicking Asian flush syndrome.  Thus it is interesting that the ALDH2*2 variant arose in the population that first discovered alcohol production.  Is it a mutation that protects against alcoholism?  One a side note, it has also been shown that those that do possess the ALDH2*2 variant but continue to drink have a higher incidence of squamous cell esophageal cancer.  So maybe, my lack of ability to drink may be a result of the excesses of my ancestors.

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