After the theory that hydrogen sulfide (H2S) might be a cause of ME/CFS, some research published in the last few years indicates that very low doses of hydrogen sulfide can protect mitochondria and prevent mitochondrial DNA damage. And a new compound called AP39 has been developed which is a mitochondrially-targeted H2S donor. Via its generation of H2S, AP39 exerts a protective effect on mitochondria. Some excerpts from articles about the benefits of hydrogen sulfide and AP39 are given below: Foods that generate H2S include garlic and onions. This study found that hydrogen sulfide is produced by red blood cells from garlic-derived organic polysulfides.