Source Naturals Oil of Oregano is made from wildcrafted true oregano(Origanum vulgare), an aromatic herb that is native to the Mediterranean region. Traditionally, oregano was used to support digestive, respiratory and joint health. Recent in vitro research indicates that carvacrol, an active constituent of oil of oregano, may provide support to the immune system. Source Naturals' Oil of Oregano is one of the most potent on the market and is standardised to 70% carvacrol.