David Chen

Behind The Mouth Biome

About

A dentist mentioned it almost in passing, somewhere between the exam and the flossing demonstration: the mouthwash she'd just recommended would kill off the good bacteria along with the bad. I asked if that was actually a problem. She shrugged and moved on to the next patient. I went home and started reading, and that was seven years ago now.

The home office is two steps from the bathroom where the real testing happens. A whiteboard leans against the wall with brand comparisons in dry-erase marker that never quite comes off clean. The mirror collects sticky notes tracking lot numbers and how long a tablet takes to fully dissolve. The medicine cabinet holds more half-used probiotic bottles than any reasonable person needs, and the standing desk usually has a spreadsheet open with a new column being filled in.

Luz Navarro, two doors down, changed how I think about the whole category before I'd even finished my first product cycle. She grows herbs, cultures her own kombucha, and once spent an hour explaining bacteria as tenants rather than invaders, a conversation that started with her returning a borrowed extension cord. That framing has outlasted every product I've tested since. Kenji Okafor, a coworker I only see in person during sprint weeks, spent two straight days making fun of the probiotic tabs I kept dissolving during stand-ups before he started asking real questions on day three. My college friend Asher Goldblatt, now in Seattle, still sends me research abstracts with a two-line summary in brackets whenever a trial produces a curve worth arguing about. He insists on treating every result as N of one, which keeps me honest about how far any single experiment can generalize.

Engineering pays the bills. This fills lunch breaks spent cross-referencing an ingredient label and the stray hour after dinner. Reader questions have built something like a small community around the testing. Tomás Vega in Phoenix sends monthly spreadsheet updates on his own protocol, changing one variable at a time with a patience I find both impressive and a little exhausting to keep up with. Nadia Holm, closer to home here in Austin, catches flavor notes in lozenges that register as nothing to me at all, and her occasional check-ins have sharpened what I pay attention to during my own trials.

Seven years of reading strain research and running these trials teaches you the science and the marketing patterns in roughly equal measure. That combination, not a credential, is what this site runs on. A dentist who actually knows your mouth has information no testing log from a South Austin bathroom can replace. Treat anything here as one data point, and let your dentist's judgment carry more weight than mine.

Written by David Chen

Disclosure

Some links here earn me a small commission if you buy through them, at no extra cost to you. Commission doesn't decide what gets tested or what gets written. A product with an affiliate program that underperformed still gets reviewed as underperforming. That isn't changing.