Oregano Overview of the Literature on Health Benefits

O regano is an herb that has been cultivated for centuries in the Mediterranean region, although now it can be found in most continents. The name oregano translates roughly into ‘‘mountain joy,’’ which explains in part its association for ancient Greeks and Romans with joy and happiness. Actually there is not simply one ‘‘oregano,’’ but rather several species that may contribute to the oregano used for culinary purposes. Origanum vulgare (also referred to as Spanish thyme and wild marjoram), a member of the plant family Lamiaceae (Labiatae), is generally the spice variety sold as oregano in Europe and the United States. Its light green leaves are used either ‘‘dry’’ or ‘‘fresh’’ as a culinary seasoning, and its use has elicited such sensory responses as ‘‘pungent,’’ ‘‘pleasantly bitter,’’ ‘‘herbaceous,’’ and ‘‘aromatic,’’ to name a few. Two constituents of oregano, carvacrol and thymol, contribute to the sensation of warmth in the mouth due to their actions on temperature-sensitive structures called ion channels. Oregano is most well known for imparting an ‘‘Italian taste’’ to Mediterranean cuisine and may be used to enhance the flavors of a variety of foods including baked goods, vegetables, legumes, fish, pizza, pasta sauce, and chilis. It has been included in aromatic teas and is a frequent addition to Mexican dishes. Mexican oregano is prepared from Lippia spp (Verbenaceae). In the Philippines, a related herb suganda (Coleus amboinicus) also is used as oregano in cooking. Medicinal uses for oregano date back to the ancient Greek and Roman empires where applications of the leaves were used to treat skin sores, to relieve aching muscles, and as an antiseptic. Oregano also has been used in traditional medicines for such ailments as asthma, cramping, diarrhea, and indigestion. In Greece, an oregano infusion is still used as a folk remedy against colds and an upset stomach and to maintain general health. Because there are so many species of Origanum used around the world as an ‘‘oregano’’ condiment and for medicinal purposes, it is not surprising that there are variations in their profiles of bioactive constituents and in the purported beneficial effects. For example, the carvacrol content of essential oils from Origanum plants may vary over 20-fold, and similarly thymol content may vary 3-fold to almost 30-fold among plant oils. The amounts of the terpene alcohol linalool could range from nondetectable in one plant oil to approximately 30% of the essential oil composition of another.