Update: further research has led me to believe that people of all races should test themselves for ALDH deficiency before using Lumina. Even if you don't exhibit AFR symptoms when drinking alcohol, your ALDH activity may still be decreased.

Many people in the rational sphere have been promoting Lumina/BCS3-L1, a genetically engineered bacterium, as an anti-cavity treatment. However, none have brought up a major negative interaction that may occur with a common genetic mutation.

In short, the treatment works by replacing lactic acid generating bacteria in the mouth with ones that instead convert sugars to ethanol, among other changes. Scott Alexander made a pretty good FAQ about this. Lactic acid results in cavities and teeth demineralization, while ethanol does not. I think this is a really cool idea, and would definitely try it if I didn't think it would significantly increase my chances of getting oral cancer.

Ethanol Metabolism: Enzymes, Steps, Reactions

Why would that be? Well, I, like around half of East Asians, have a mutation in my acetaldehyde dehydrogenase (ALDH) which results in it being considerably less active. This is known as Asian/Alcohol Flush Reaction (AFR). This results in decreased ability to metabolize acetaldehyde to acetate and consequently a much higher level of acetaldehyde when drinking alcohol. Although the time ingested ethanol spends in the mouth and stomach are quite short, alcohol dehydrogenase activity by both human and bacterial cells rises rapidly once the presence of ethanol is detected. Some studies have estimated that ~20% of consumed ethanol is converted to acetaldehyde in the mouth and stomach in a process called first pass metabolism. Normally, this is broken down into acetate by the ALDH also present, but it instead builds up in those with AFR. Acetaldehyde is a serious carcinogen and people with AFR have significantly higher levels of oral and stomach cancer (The odds ratios for Japanese alcoholics with the mutation in relation to various cancers are >10 (!!!) for oral and esophageal cancer). The Japanese paper also notes that all alcoholics tested only had a single copy of the mutation, since it is very difficult to become an alcoholic with two copies (imagine being on high dosage Antabuse your entire life - that's the same physiological effect).

In addition, there is also the potential for change in oral flora and their resting ADH levels. As oral flora an...

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