June-sang Yang, MD

For eight years at a clinic in Gangnam, Seoul, June-sang Yang, MD has directly measured patients' breath gases — including hydrogen sulfide (H₂S) and methyl mercaptan (CH₃SH), the sulfur gases that standard breath panels routinely leave out. That measurement is the backbone of the clinical frame he calls Neo-Skepticism: many chronic, hard-to-pin-down symptoms — bloating, bad breath, brain fog, cravings, skin problems — are downstream effects of bacterial overgrowth in the gut, not separate diseases.

The recurring, counterintuitive observation is that the foods widely taught as "healthy" — fiber, whole grains, sulfur-rich vegetables, fermented foods, probiotics — can act as fuel for that overgrowth. The frame is not a single prescriptive diet; it is a way of reading the body's signals, with the smell and composition of the gas as a diagnostic thread.