|Oregano leaf, oregano oil side effects, oregano oil benefits, oregano oil uses
December 6, 2011
Oregano Oil and Leaf Compositions
Oregano oils are rich in carvacrol. Baser KH., Anadolu University, Turkey, pointed out that carvacrol is responsible for
the biological activities of oregano. Dr. Baser further stated that carvacrol might possibly offer many health benefits
such as antimicrobial, antitumor, antimutagenic, antigenotoxic, analgesic, antispasmodic, antiinflammatory, angiogenic,
antiparasitic, antiplatelet, AChe inhibitory, antielastase, insecticidal, antihepatotoxic and hepatoprotective activities and
uses such as feed additive.  Oil from oregano leave contains mainly carvacrol, trans-sabinene hydrate, cis-piperitol,
borneol, terpinen-4-ol, and linalool. [A1] Oregano oil was mainly composed of monoterpenes and sesquiterpenes.
Monoterpene fraction was found to have linalyl acetate, sabinene, gamma-terpinene, trans-ocimene, and cis-ocimene.
Low percentages of the phenolic monoterpenoids (thymol and carvacrol) were also detected in the oil. The main
components of sesquiterpenoid were beta-caryophyllene, caryophyllene oxide, germacrene D, and gamma-elemene. 
Extracts of oregano leaves contain flavanones, dihydroflavonols, favonols and flavones. [A2] Water soluble ingredients
from the leaves are 4'-O-beta-D-glucopyranosyl-3',4'-dihydroxybenzyl protocatechuate and 4'-O-beta-D-glucopyranosyl-
3',4'-dihydroxybenzyl 4-O methylprotocatechuate. [A3] Extracts from oregano leaves have antioxidant activities. [A2-A4]
Monoterpenes are dietary components found in most of the plant oils and most of these monterpenes showed antitumor
activity in cell or test-tube studies. Carvacrol, one of the key ingredient from gregano oil was demonstrated to have
antitumor activity in a study of myoblast cells, CO25. 
A study was performed on Young white rats received sodium selenite subcutaneously on day 13 post partum during two
months in 2009. Cataract formation and intensity was detected and measured by slit-lamp. Oregano extract (Dosage 2
g kg(-1)) was given (1-2 times) intraperitoneal at different times with respect to the selenite administration lens
opacification was analyzed in selenite, selenite-Oregano, oregano and control groups on day 7 after selenite
administration. Oregano extract have revealed a significant protective effect against selenite induced cataract when
injected 1 and 2 day (2 times) before selenite injection. Thus, oregano extract may benefit animals at risk of cataract
Aqueous extract of oregano leaves showed benefits toward diabetic rats. It lowered the sugar blood level to the normal
values in rats. [A6]
Extracts from the oregano leaves have insecticide activities. Thymol, carvacrol,
(1R)-(+)-alpha-pinene and (1S)-(-)-alpha-pinene were the most toxic. [A5]
In a study of 36 rats, oregano extracts showed apparent protective and curative effects on Cd-induced hepatotoxicity
and nephrotoxicity. Thus, oregano extracts may have benefits of promoting health in rats.
Very limited studies have been done for the health benefits of oregano. Oil extracted from Oregano leaves is found to
have antimicrobial activity. Its ingredient, carvacrol is the most effective in the study. [A1] Chitosan edible films
incorporating Mexican oregano or cinnamon essential oil could improve the quality of foods by the action of the volatile
compounds on surface growth of molds. [B1] Oregano oil was shown to prevent the growth of E. coli O157:H7 in foods.
 Researchers from URI-Campus de Erechim, Brazil, reported the antimicrobial activity in fresh sausage of oregano
essential oil against several species of bacteria based on an in vitro study of fresh sausage.  Researchers from Avian
Sciences Research Centre, SAC, Edinburgh, demonstrated that oregano oil had limited effects on intestinal microflora
in female chicks. 
Oregano oil (Oreganum vulgare) was orally administered to 14 adult patients suffered from enteric parasites,
Blastocystis hominis, Entamoeba hartmanni and Endolimax nana. After 6 weeks of supplementation with 600 mg
emulsified oil of oregano daily, Entamoeba hartmanni (four cases), Endolimax nana (one case), and Blastocystis
hominis in (eight cases) was undetected in the patients. Gastrointestinal symptoms also improved in seven of the 11
In in vivo wound healing experimental models of rats and mice, a formulation of Hypericum perforatum oil and sage and
oregano essential oils shows a promising result. [B4]
Oregano oil has been shown to inhibit lipid oxidation in meat during refrigerated storage. Lipid oxidation causes color
changes, texture of the meat. In some cases, lipid oxidation can be toxic. … Can I consider this as a kind of benefit of
oregano oil?  Anyway, there is also one article suggesting that oregano oil is anti-inflammatory. 
oregano oil side effects
There are no scientific studies about oregano oil side effects on human subjects, but origanum essential oil has been
experimented on rat's operant conditioning behavior. At the high doses the oil caused a depressive effect (probably due
to toxicity) while at the lowest doses they caused weak or doubtful effects, probably related to a direct action on the
central nervous system.  Not sure if this oregano oil side effects also happens in human. If you experience any side
effects because of using oregano extracts or its oil, you must stop using it and discuss with your doctor.
[A1] Santoyo S, Cavero S, Jaime L, Ibañez E, Señoráns FJ, Reglero G. Supercritical carbon dioxide extraction of compounds with
antimicrobial activity from Origanum vulgare L.: determination of optimal extraction parameters. J Food Prot. 2006 Feb;69(2):369-75.
School: Ciudad Universitaria de Cantoblanco, Madrid, Spain:[A2] Rodríguez-Meizoso I, Marin FR, Herrero M, Señorans FJ, Reglero G,
Cifuentes A, Ibáñez E. Subcritical water extraction of nutraceuticals with antioxidant activity from oregano. Chemical and functional
characterization. J Pharm Biomed Anal. 2006 Aug 28;41(5):1560-5. Epub 2006 Feb 20. Instituto de Fermentaciones Industriales (CSIC),
Spain. [A3] Matsuura H, Chiji H, Asakawa C, Amano M, Yoshihara T, Mizutani J. DPPH radical scavengers from dried leaves of oregano
(Origanum vulgare). Biosci Biotechnol Biochem. 2003 Nov;67(11):2311-6. Northern Advancement Center for Science & Technology, Japan.
 Zheng W, Wang SY. Antioxidant activity and phenolic compounds in selected herbs. J Agric Food Chem. 2001 Nov;49(11):5165-70. U. S.
Department of Agriculture, USA. [A5] Traboulsi AF, Taoubi K, el-Haj S, Bessiere JM, Rammal S. Insecticidal properties of essential plant
oils against the mosquito Culex pipiens molestus (Diptera: Culicidae). Pest Manag Sci. 2002 May;58(5):491-5. Lebanese University,
Beirut, Lebanon. firstname.lastname@example.org. [A6] 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 Jun;92(2-3):251-6. UFR PNPE, BP 21,
Errachidia 52000, Morocco.  Busatta C, Vidal RS, Popiolski AS, Mossi AJ, Dariva C, Rodrigues MR, Corazza FC, Corazza ML, Vladimir
Oliveira J, Cansian RL. Application of Origanum majorana L. essential oil as an antimicrobial agent in sausage. Food Microbiol. 2008 Feb;
25(1):207-11. Epub 2007 Jul 28.  Baser KH Biological and pharmacological activities of carvacrol and carvacrol bearing essential oils.
Curr Pharm Des. 2008;14(29):3106-19.  Cross DE, McDevitt RM, Hillman K, Acamovic T. The effect of herbs and their associated
essential oils on performance, dietary digestibility and gut microflora in chickens from 7 to 28 days of age. Br Poult Sci. 2007 Aug;48(4):496-
506.  Fundarò A, Cassone MC. Action of essential oils of chamomile, cinnamon, absinthium, mace and origanum on operant
conditioning behavior of the rat, Boll Soc Ital Biol Sper. 1980 Nov 30;56(22):2375-80.  Zeytinoglu H, Incesu Z, Baser KH. Inhibition of DNA
synthesis by carvacrol in mouse myoblast cells bearing a human N-RAS oncogene. Phytomedicine. 2003 May;10(4):292-9.  Govaris A,
Botsoglou N, Papageorgiou G, Botsoglou E, Ambrosiadis I. Dietary versus post-mortem use of oregano oil and/or alpha-tocopherol in
turkeys to inhibit development of lipid oxidation in meat during refrigerated storage. Int J Food Sci Nutr. 2004 Mar;55(2):115-23.  Burt SA,
Reinders RD. Antibacterial activity of selected plant essential oils against Escherichia coli O157:H7. Lett Appl Microbiol. 2003;36(3):162-7.
 Force M, Sparks WS, Ronzio RA. Inhibition of enteric parasites by emulsified oil of oregano in vivo. Phytother Res. 2000 May;14(3):213-4.
 Afsharypour S, Sajjadi SE, Erfan-Manesh M. Volatile constituents of Origanum vulgare ssp. viride (syn. O. heracleoticum) from Iran.
Planta Med. 1997 Apr;63(2):179-80.  Bukovská A, Cikos S, Juhás S, Il'ková G, Rehák P, Koppel J. Effects of a combination of thyme and
oregano essential oils on TNBS-induced colitis in mice. Mediators Inflamm. 2007;2007:23296. [B1] Avila-Sosa R, et al, Antifungal activity by
vapor contact of essential oils added to amaranth, chitosan, or starch edible films. Int J Food Microbiol. 2011 Oct 30 [B2] Shati AA. Effects of
Origanum majorana L. on cadmium induced hepatotoxicity and nephrotoxicity in albino rats. Saudi Med J. 2011 Aug;32(8):797-805. [B3]
Dailami KN, et al, Prevention of selenite-induced cataractogenesis by Origanum vulgare extract. Pak J Biol Sci. 2010 Aug 1;13(15):743-7.
[B4] Süntar I, et al, A novel wound healing ointment: a formulation of Hypericum perforatum oil and sage and oregano essential oils based
on traditional Turkish knowledge. J Ethnopharmacol. 2011 Mar 8;134(1):89-96.
Oregano (Origanum vulgare) is native to Europe, the Mediterranean region and southern and central Asia. Oregano is a derivation from the Greek
origanon "mountain" and the verb ganousthai "delight in". Its leaves are commonly used in Greek and Italian cuisine. Oregano is a perennial herb,
with purple flowers. Oregano is also called as wild marjoram. [Wikipedia.com] The key phytochemicals of oregano include carvacrol, thymol,
limonene, pinene, ocimene, and caryophyllene. The leaves and flowering stems of oregano are strongly antiseptic, antispasmodic, carminative,
cholagogue, diaphoretic, emmenagogue, expectorant, stimulant, stomachic and mildly tonic. Oregano leaves have an aromatic, warm and slightly
bitter taste. Oregano herb goes well with tomato sauces, lamb, cruciform vegetables, pizza, and other spices. Oregano has an high antioxidant
activity, due to a high content of phenolic acids and flavonoids. [Wikipedia.com] This article summarizes its health benefits, as the health benefits of
Oregano contains many phytonutrients, such as thymol and rosmarinic acid, and they are potent antioxidants. Antioxidants can prevent
oxygen-based damage to cell structures. Oregano is also a good source of fibers. Usually, foods high in fiber are able to lower high cholesterol
levels. Oregano nutrition fact is wonderful. It is a good source of calcium, vitamins C and A and omega-3 fatty acids, it also has vitamin k,
manganese, iron, calcium, vitamin E and tryptophan. Dried or fresh leaf of oregano can be made into a tea by immersing 1 to 2 teaspoons of
oregano leaf in hot water for ten minutes. Thus, we can imagine oregano benefits are many. Here we are going review some interesting findings
about the health benefits of oregano and its oil.
Different people may experience different side effects and benefits of an oregano product. You are encouraged to
report adverse side effects to FDA, its website is www.fda.gov., or report the adverse side effects to the
manufacturer, you should be able to find the contact information on the label.
There are always new information. Please, send me an email (email@example.com) to correct my mistake(s).
Reasonable care has been taken in preparing this document and the information provided herein is believed to be
accurate. The information is not intended to be a substitute for professional medical advice. It is important to seek
the advice of a physician about any medical condition or symptom or the benefits and side effects of a oregano
supplement or a drug product. Finally, please, do not transfer the article to other website. Thank you. ALL RIGHTS