The oregano leaf has been used for thousands of years for culinary and medicinal purposes. Turkish, Spanish, Mexican and Greek oregano contain different amounts of carvacrol, thymol and other active ingredients. Origanum Vulgare from Greece is thought to have the greatest medicinal value. According to Drugs.com, oregano is safe when used as a food but should be used with caution if you are pregnant, diabetic, have sensitive skin or if you have plant allergies.
The two main active ingredients in Oregano are the phenols carvacrol and thymol. Dr. A. Anderson in the 2006 supplement of the “International Journal of Toxicology” reports that animals exposed to the oregano leaf rarely developed skin irritations. However, the Environmental Working Group reports that these substances are easily absorbed and can cause skin irritation, especially in infants, children and with exposure to mucous membranes such as the eyes or nostrils.
Thymol is one of the active ingredients in the oregano leaf. Some species of Mexican oregano, or Lippea Graveolens, have considerably more thymol than Greek oregano, or oregano vulgare, whose primary component is carvacrol. Thymol has been used as a pesticide and the Material Safety Data Sheet reports that chronic exposure to thymol can cause damage to the Kidneys, liver, central nervous system and mucous membranes.
People who have allergies to other herbs should use caution before consuming oregano. The oregano leaf is in the labiatae family and can cause severe allergic reactions in individuals who are allergic to sage, mint, basil, lavender and marjoram, which are other herbs in the labiatae family, according to Dr. M. Benito in the “Annals of Allergy, Asthma and Immunology."
Pregnancy Side Effects
Inadequate levels of iron during pregnancy are known to cause problems with the developing fetus. Pregnant women should limit oregano consumption because the phenols in oregano may reduce iron absorption. Another reason to avoid oregano during pregnancy is because it is a phyto-estrogen that has been used in traditional medicine to terminate pregnancies and to bring on menstruation. Oregano is safe when used as a food additive but that large dosage of oregano should be avoided during pregnancy.
The Glucosides found in the oregano leaf can lower blood sugar, reports the January 2008 “Journal of Natural Medicine.” Diabetics who are on medication to lower their blood sugar should use caution when using oregano because of the possibility of hypoglycemia.
According to CAMline Reviews, oregano can occasionally cause gastrointestinal upset if taken in high doses. No reported complaints of stomach upset have occurred when using oregano to spice foods.
- ScienceLab: Material Safety Data Sheet: Thymol
- CAMline Reviews: Oregano
- European Journal of Clinical Nutrition: Iron Absorption and Phenolic Compounds: Importance of Different Phenolic Structures
- Journal of Toxicology. Clinical Toxicology: Herbal Infusions Used for Induced Abortion
- Drugs.com: Oregano