I'm in America and every once in a while I come across someone with food stuck in their teeth. Recently it happened with a coworker I feel friendly towards. I first noticed while we were having a 1:1 chat but there was another person in the room. I felt like I should give them a heads up but I also don't want them to feel embarrassed especially because it wasn't just the two of us.
How do you tell someone they have food stuck in their teeth while minimizing any possible embarrassment they might feel?