23andme says I’m a slow caffeine metabolizer because I have the AC genotype at SNP rs762551. You’d think that means I’m extra sensitive to caffeine before bedtime, but that’s not the case: I sleep just fine even if I have a cup of high-octane coffee after dinner. My 99-year-old grandmother drinks coffee by the potful, crediting its warmth as a calming effect to make her drowsy.
This week's Economist points to a new study in Nature by Javier A. Ceja-Navarro et al that names Pseudomonas Fulva as a bacterium active in the guts of a coffee bean pest. Caffeine is normally toxic to insects, but P. Fulva neutralizes the caffeine, apparently using the demethylase ndmA gene.
I wish I knew enough genetics to test a theory that occurs to me: maybe my own caffeine metabolism is also affecting by a similar gut bacteria that I have in abundance but which is missing in other people. I already checked for Pseudomonas Fulva — I don’t have it in any of my uBiome samples. I do have abundant levels of the genus Pseudomonas, but that is not the same thing.
It should be possible to screen every one of my gut bacteria demethylizing ndMA gene, but I’m not sure how to do that. If I did find the gene in one of the gut bacteria I harbor, then that would be pretty cool: a microbe that helps me drink coffee.