Oregano
Scientific Name(s): Origanum vulgare L. Family: Lamiaceae (mints)
Common Name(s): Mediterranean oregano , mountain mint , wild marjoram , winter marjoram , wintersweet
Clinical Overview
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Uses of Oregano
Aside from its culinary application, oregano exhibits antimicrobial and antioxidant actions and has possible activity as an antispasmodic and in diabetes. However, there is no clinical evidence to support the use of oregano in any indication.
Oregano Dosing
There is no clinical evidence to support specific therapeutic doses of oregano; however, due to its wide use in foods it has been designated “generally recognized as safe” (GRAS) by the FDA. In a small study, 200 mg/day emulsified O. vulgare oil was administered for 6 weeks.
Contraindications
Contraindications have not been identified.
Pregnancy/Lactation
Information in humans is lacking. Generally recognized as safe when used as a food substance. Avoid dosages above those found in foods because safety and efficacy are unproven. Some studies indicate hormonal effects.
Oregano Interactions
None well documented.
Oregano Adverse Reactions
Oregano has caused allergic contact dermatitis when applied topically. When oregano is ingested, eczematous rash and, rarely, anaphylactic reactions can occur.
Toxicology
Information in humans is lacking. An increase in the proportion of dead cells in preimplantation mice embryos has been observed following oregano essential oil consumption.
Botany
Common or wild oregano is a perennial plant native to the Mediterranean region and Asia and cultivated in the United States. Its creeping rootstock produces a square, downy, purplish stem with opposite ovate leaves. Stems can grow up to 76 cm tall and are dotted with small depressions. Purple, 2-lipped flowers grow in terminal clusters from July to October. 1 , 2 , 3
The O. vulgare subspecies hirtum has a spicy flavor, furry leaves on the stems that grow up to 45.7 cm tall, and floppy white flowers. 1 Other wild species have little flavor.
History
Oregano has been a common ingredient in Spanish, Mexican, and Italian dishes as a spice and flavoring agent for hundreds of years. Its initial purpose was as a warming digestive and circulatory stimulant. It has been used in perfumery for its volatile oil contents, especially in scenting soaps.
The antiseptic qualities of aromatic and medicinal plants and their extracts have been recognized since antiquity. Attempts to characterize these properties in the laboratory date back to the early 1900s.
Antispasmodic, calmative, carminative, diaphoretic, expectorant, stomachic, and tonic actions have been reported. It has been suggested that an infusion of the fresh herb is beneficial in treating an upset stomach and indigestion, headache, colic, and nervous complaints, as well as for coughs and other respiratory ailments. An infusion of the flowers has been used to prevent seasickness. The oil has been used externally in liniments and lotions and to ease toothache. It has also been used as an ant repellent. 4 , 5 , 6
Chemistry
Oregano contains oleanolic and ursolic acids, flavonoids and hydroquinones, caffeic, rosemarinic, and lithospermic acid, tannins, and phenolic glycosides. Phenolic compounds represent 71% of the total oil. The polar phenols thymol and carvacrol are responsible for many of the properties of the essential oil, as well as p-cymene and terpinene. 2 , 7 , 8 , 9 , 10 , 11 , 12
Oregano Uses and Pharmacology
There are few clinical studies on the medicinal effects of oregano, despite its widespread culinary use.
Antioxidant activityMany experiments have demonstrated that in vitro antioxidant activity of oregano essential oil and its constituent compounds rosmarinic acid, carvacrol, and thymol are similar to or better than alpha tocopherol. 3 , 9 , 13 , 14 , 15 , 16 The clinical importance of this effect is not yet established. In a double-blind, placebo-controlled trial among healthy adult men, no differences in biomarkers of lipid peroxidation were found. 17
Antifungal activityOregano inhibited aflatoxin and prevented growth of Aspergillus at concentrations as low as 0.1%. 18 , 19 , 20 Further studies have compared the effects of oregano essential oil, thymol, and carvacrol. All 3 completely inhibited fungal growth of Aspergillus and Penicillium species. 21 Oregano oil has some antifungal activity against Candida species, possibly because of its carvacrol content. 8 , 12
Antibacterial activityThe volatile oils of oregano have demonstrated in vitro antibacterial activity against a wide range of gram-positive and gram-negative microorganisms including Listeria , Pseudomonas , Proteus , Salmonella , and Clostridium species, 5 , 9 , 10 , 22 , 23 , 24 , 25 , 26 , 27 , 28 as well as some methicillin-resistant staphylococci. 9 , 29 Low to moderate activity against Helicobacter pylori has been demonstrated. 30 , 31 Oregano oil appears to inhibit organisms at relatively low concentrations, 32 and its activity could be due to the phenolic components thymol and carvacrol. 9 , 29
Antiparasitic actionIn 1 study, 14 patients with known parasites were administered 200 mg emulsified O. vulgare oil for 6 weeks. Entamoeba hartmanni , Endolimax nana , and Blastocystis hominis were eradicated from 13 patients. 33
The oil of O. vulgare has been shown to eradicate common parasites in chickens and pheasants. In vitro experiments showed activity against Trypanosoma cruzi . 34
Antispasmodic effectsOriganum compactum has been used in Morocco as a spasmolytic, prepared as a tea from flowers and leaves of the plant. The rapid spasmolytic action of O. compactum was demonstrated in in vitro experiments after using acetylcholine on smooth muscle preparations to produce contractions. It is suspected that the herb stabilizes the muscle membrane by interfering with the influx of calcium and its regulatory proteins. 2 The active components in O. compactum appear to be thymol and carvacrol in the essential oil. 35
DiabetesResearchers have demonstrated a hypoglycemic effect of oregano in rats with induced diabetes. This provides some support to the use of oregano leaves by individuals with diabetes. This effect was independent of insulin and occurred after a single dose as well as with repeated daily dosing. 36
Other researchers have demonstrated an aldose reductase inhibitor effect by lithospermic and rosmarinic acid extracted from oregano. Some researchers suggest that inhibiting the accumulation of sorbitol may contribute to the prevention of chronic complications, such as retinopathy and peripheral neuropathy in diabetic patients. 7 , 37
Dosage
There is no clinical evidence to support specific therapeutic doses of oregano; however, due to its wide use in foods it has been designated “generally recognized as safe” by the FDA. 38 A study evaluating the antiparasitic effect of oregano used 200 mg emulsified O. vulgare oil daily for 6 weeks. 33
Pregnancy/Lactation
Information in humans is lacking. Generally recognized as safe when used as a food substance.
Retrospective review of poison center data in Uruguay from 1986 to 1999 analyzed an over-the-counter herbal preparation containing oregano and other herbs ( Carachipita ) commonly used in attempted abortion. GI symptoms, genital hemorrhage, and multiple organ system failure resulted in 4 abortions in 13 women who received this preparation. 39 Dried oregano herb (1 g) contains approximately 4 mcg of phytoprogestins, which bind to progestin-binding sites. 40
In a study of natural herbs as alternatives to antimicrobials, a decrease in sow and litter mortality occurred in an experiment in which sows were fed oregano leaf, flower, and essential oil-enriched food. No apparent ill effect was reported. 41 Another study found that mice fed oregano essential oil showed an increase in the proportion of dead cells in preimplantation embryos. 42
Interactions
None well documented.
Adverse Reactions
Allergic contact dermatitis caused by spices, including oregano, is well documented. 42 Although oregano is frequently consumed, there are a few reports of adverse or systemic reactions. One report of anaphylaxis exists. Cross-sensitivity with other members of the Laminaceae family has been noted. 43 An additional case report of an eczematous reaction to ingestion of large quantities of oregano has been published. 44
Toxicology
In a study investigating the effect of oregano on growth and development of mouse embryos, an increase in the proportion of dead cells in preimplantation embryos was observed. 42
Bibliography
1. Origanum vulgare L. USDA, NRCS. 2007. The PLANTS Database ( http://plants.usda.gov , 30 January 2007). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.2. Van Den Broucke CO , Lemli JA . Antispasmodic activity of Origanum compactum . Planta Med . 1980;38:317-331.
3. Lagouri V , Boskou D . Nutrient antioxidants in oregano . Int J Food Sci Nutr . 1996;47:493-497.
4. Assaf MH , Ali AA , Makboul MA , Beck JP , Anton R . Preliminary study of phenolic glycosides from Origanum majorana ; quantitative estimation of arbutin; cytotoxic activity of hydroquinone . Planta Med . 1987;53:343-345.
5. Dorman HJ , Deans SG . Antimicrobial agents from plants: antibacterial activity of plant volatile oils . J Appl Microbiol . 2000;(88):308-316.
6. Lust JB . The Herb Book . New York, NY: Bantam Books; 1980.
7. Koukoulitsa C , Zika C , Geromichalos GD , Demopoulos VJ , Skaltsa H . Evaluation of aldose reductase inhibition and docking studies of some secondary metabolites, isolated from Origanum vulgare L. ssp. hirtum . Bioorg Med Chem . 2006;14:1653-1659. Epub 2005 Oct 24.
8. Giordani R , Regli P , Kaloustian J , Mikail C , Abou L , Portugal H . Antifungal effect of various essential oils against Candida albicans . Potentiation of antifungal action of amphotericin B by essential oil from Thymus vulgaris . Phytother Res . 2004;18:990-995.
9. Bozin B , Mimica-Dukic N , Simin N , Anackov G . Characterization of the volatile composition of essential oils of some lamiaceae spices and the antimicrobial and antioxidant activities of the entire oils . J Agric Food Chem . 2006;54:1822-1828.
10. Dadalioglu I , Evrendilek GA . Chemical compositions and antibacterial effects of essential oils of Turkish oregano ( Origanum minutiflorum ), bay laurel ( Laurus nobilis ), Spanish lavender ( Lavandula stoechas L.), and fennel ( Foeniculum vulgare ) on common foodborne pathogens . J Agric Food Chem . 2004;52:8255-8260.
11. Daferera DJ , Ziogas BN , Polissiou MG . GC-MS analysis of essential oils from some Greek aromatic plants and their fungitoxicity on Penicillium digitatum . J Agric Food Chem . 2000;48:2576-2581.
12. Tampieri MP , Galuppi R , Macchioni F , et al . The inhibition of Candida albicans by selected essential oils and their major components . Mycopathologia . 2005;159:339-345.
13. Vichi S , Zitterl-Eglseer K , Jugl M , Franz C . Determination of the presence of antioxidants deriving from sage and oregano extracts added to animal fat by means of assessment of the radical scavenging capacity by photochemiluminescence analysis . Nahrung . 2001;45:101-104.
14. Faleiro L , Miguel G , Gomes S , et al . Antibacterial and antioxidant activities of essential oils isolated from Thymbra capitata L. (Cav.) and Origanum vulgare L . J Agric Food Chem . 2005;53:8162-8168.
15. Zheng W , Wang SY . Antioxidant activity and phenolic compounds in selected herbs . J Agric Food Chem . 2001;49:5165-5170.
16. Ivanova D , Gerova D , Chervenkov T , Yankova T . Polyphenols and antioxidant capacity of Bulgarian medicinal plants . J Ethnopharmacol . 2005;96:145-150.
17. Nurmi A , Mursu J , Nurmi T , et al . Consumption of juice fortified with oregano extract markedly increases excretion of phenolic acids but lacks short- and long-term effects on lipid peroxidation in healthy nonsmoking men . J Agric Food Chem . 2006;54:5790-5796.
18. Basilico MZ , Basilico JC . Inhibitory effects of some spice essential oils on Aspergillus ochraceus NRRL 3174 growth and ochratoxin A production . Lett Appl Microbiol . 1999;29:238-241.
19. Llewellyn GC , Burkett ML , Eadie T . Potential mold growth, aflatoxin production, and antimycotic activity of selected natural spices and herbs . J Assoc Off Anal Chem . 1981;64:955-960.
20. Tantaoui-Elaraki A , Beraoud L . Inhibition of growth and aflatoxin production in Aspergillus parasiticus by essential oils of selected plant materials . J Environ Pathol Toxicol Oncol . 1994;13:67-72.
21. Akgul A , Kivanc M . Inhibitory effects of selected Turkish spices and oregano components on some foodborne fungi . Int J Food Microbiol . 1988;6:263-268.
22. Elgayyar M , Draughon FA , Golden DA , Mount JR . Antimicrobial activity of essential oils from plants against selected pathogenic and saprophytic microorganisms . J Food Prot . 2001;64:1019-1024.
23. Kivanc M , Akgul A , Dogan A . Inhibitory and stimulatory effects of cumin, oregano and their essential oils on growth and acid production of Lactobacillus plantarum and Leuconostoc mesenteroides . Int J Food Microbiol . 1991;13:81-85.
24. Marino M , Bersani C , Comi G . Impedance measurements to study the antimicrobial activity of essential oils from Lamiaceae and Compositae . Int J Food Microbiol . 2001;67:187-195.
25. Tsigarida E , Skandamis P , Nychas GJ . Behaviour of Listeria monocytogenes and autochthonous flora on meat stored under aerobic, vacuum and modified atmosphere packaging conditions with or without the presence of oregano essential oil at 5 degrees C . J Appl Microbiol . 2000;89:901-909.
26. Ultee A , Gorris LG , Smid EJ . Bactericidal activity of carvacrol towards the food-borne pathogen Bacillus cereus . J Appl Microbiol . 1998;85:211-218.
27. Chorianopoulos N , Kalpoutzakis E , Aligiannis N , Mitaku S , Nychas GJ , Haroutounian SA . Essential oils of Satureja, Origanum, and Thymus species: chemical composition and antibacterial activities against foodborne pathogens . J Agric Food Chem . 2004;5:8261-8267.
28. Burt SA , Reinders RD . Antibacterial activity of selected plant essential oils against Escherichia coli O157:H7 . Lett Appl Microbiol . 2003;36:162-167.
29. Nostro A , Blanco AR , Cannatelli MA , et al . Susceptibility of methicillin-resistant staphylococci to oregano essential oil, carvacrol and thymol . FEMS Microbiol Lett . 2004;230:191-195.
30. Stamatis G , Kyriazopoulos P , Golegou S , Basayiannis A , Skaltsas S , Skaltsa H . In vitro anti- Helicobacter pylori activity of Greek herbal medicines . J Ethnopharmacol . 2003;88:175-179.
31. Mahady GB , Pendland SL , Stoia A , et al . In vitro susceptibility of Helicobacter pylori to botanical extracts used traditionally for the treatment of gastrointestinal disorders . Phytother Res . 2005;19:988-991.
32. Hammer KA , Carson CF , Riley TV . Antimicrobial activity of essential oils and other plant extracts . J Appl Microbiol . 1999;86:985-990.
33. Force M , Sparks WS , Ronzio RA . Inhibition of enteric parasites by emulsified oil of oregano in vivo . Phytother Res . 2000;14:213-214.
34. Santoro GF , das Gracas Cardoso M , Guimaraes LG , Salgado AP , Menna-Barreto RF , Soares MJ . Effect of oregano ( Origanum vulgare L.) and thyme ( Thymus vulgaris L.) essential oils on Trypanosoma cruzi (Protozoa: Kinetoplastida) growth and ultrastructure . Parasitol Res . 2007;100:783-790. Epub 2006 Oct 6.
35. Van den Broucke CO , Lemli JA . Antispasmodic activity of Origanum compactum . Part 2: Antagonistic effect of thymol and carvacrol . Planta Med . 1982;45:188-190.
36. Lemhadri A , Zeggwagh NA , Maghrani M , Jouad H , Eddouks M . Anti-hyperglycaemic activity of the aqueous extract of Origanum vulgare growing wild in Tafilalet region . J Ethnopharmacol . 2004;92:251-256.
37. Koukoulitsa C , Zika C , Hadjipavlou-Litina D , Demopoulos VJ , Skaltsa H . Inhibitory effect of polar oregano extracts on aldose reductase and soybean lipoxygenase in vitro . Phytother Res . 2006;20:605-606.
38. US Department of Health and Human Services. Food and Drug Administration Center for Food Safety and Applied Nutrition. Substances Generally Recognized as Safe. December 2004. http://www.cfsan.fda.gov/∼lrd/fcf182.html . Code of Federal Regulations , title 21, vol. 3. 21 CFR 182. Revised April 1, 2003. Accessed April 11, 2007.
39. Ciganda C , Laborde A . Herbal infusions used for induced abortion . J Toxicol Clin Toxicol . 2003;41:235-239.
40. Zava DT , Dollbaum CM , Blen M . Estrogen and progestin bioactivity of foods, herbs, and spices . Proc Soc Exp Biol Med . 1998;217:369-378.
41. Allan P , Bilkei G . Oregano improves reproductive performance of sows . Theriogenology . 2005;63:716-721.
42. Domaracky M , Rehak P , Juhas S , Koppel J . Effects of selected plant essential oils on the growth and development of mouse preimplantation embryos in vivo . Physiol Res . 2007;56:97-104.
43. Futrell JM , Rietschel RL . Spice allergy evaluated by results of patch tests . Cutis . 1993;52:288-290.
44. Benito M , Jorro G , Morales C , Pelaez A , Fernandez A . Labiatae allergy: systemic reactions due to ingestion of oregano and thyme . Ann Allergy Asthma Immunol . 1996;76:416-418.
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