2. Historical benefits of H2S
The ancient Greeks, Egyptians, and Romans regularly bathed in natural sulfur springs as treatments for disease [6]. Depending on the microbiota and oxygen content, sulfur springs typically contain H2S concentrations ranging from 1 to 500 mM [7] with anti-inflammatory, anti-bacterial, vasodilatory, and anti-fungal properties attributed to the sulfur-containing water [8]. Epide-
miological studies report that a diet rich in organosulfur species is associated with longevity and decreased morbidity [9]. Members of the Allium genus (garlic and onions), which contain organosul- fur compounds have a well-documented history of health benefits [10]. Indeed, garlic-derived compounds such as diallyl trisulfide release H2S in the presence of cellular reductants like glutathione (GSH) [11]. Populations that consume garlic regularly have low blood pressure, low cholesterol, and less vascular disease [12]. While administration of exogenous sulfur-containing compounds shows strong promise as therapies, H2S is also endogenously produced in many different human tissues.