Oregano leaf odor regulates sodium chloride consumption in mice.

This study investigates how the odor of oregano (genus Origanum) and its main volatile component, carvacrol, affect salt preference in C57BL/6J mice. Using a 2-bottle choice test comparing distilled water and 0.15 M sodium chloride (NaCl), the researchers found that exposure to oregano odor or carvacrol significantly reduced salt intake and preference, particularly in female mice. Chemical analysis identified carvacrol as the predominant volatile in dried oregano, and immunohistochemical analysis showed increased c-Fos expression—a marker of neuronal activation—in the ventral bed nucleus of the stria terminalis (BNST), a brain region involved in salt appetite regulation. These findings suggest that olfactory cues from oregano, mediated partly by carvacrol, modulate salt consumption by stimulating specific brain areas, highlighting potential applications for managing dietary sodium intake.