If a patient has a flat-line result on a SIBO breath test and you treat as positive for hydrogen sulfide bacteria, is there a way to retest to make sure that the treatment is successful? Even though the breath test is not measuring for hydrogen sulfide, could you expect that the repeated breath test would show a normal result or least a changed result that would no longer be flat? How do you know when you’re done treating?

Chris Kresser:  Those are all the operative questions here, and that’s why the hydrogen sulfide thing is problematic. As you have pointed out, there is no way to know when you’re done. We might expect, if you understand what’s happening, which is that the hydrogen sulfide-producing species are outcompeting the methane and hydrogen-producing species, that when you treat and kill some of the hydrogen sulfide bacteria, maybe some of the hydrogen-producing bacteria would come back and you’d see kind of a normal distribution of hydrogen throughout the test. That’s kind of, in my mind, what would make the most sense as a result to see after you treat. And if you did see that, like hydrogen was normal and methane was zero, below 3 throughout the test, then in my mind, I would be done with that treatment.