Internal Use of Oregano: An Exploration

by Jade Shutes

Oregano: Origanum vulgare

by Jade Shutes

My interest in writing this article comes from the ongoing questions I receive from individuals regarding the internal use of essential oils.  This week a student wrote in and asked about the internal use of Oregano and since I have been interested in the Oregano supplements I see at Whole Foods I decided to dive in and explore why Oregano supplements are gaining in popularity and what the difference is between taking the essential oil oregano internally versus supplements available from reputable supplement/herbal/vitamin companies such as Gaia Herbs and New Chapter.

We shall begin by exploring the two products on the market (that I feel 100% confident with). There are many others on the market, some questionable.


Internal use of Oregano supplements:  

According to New Chapter:  Oregano Force (their product) reduces oxidative stress, is a free-radical scavenger, and supports a healthy immune system. Oregano was used by ancient Greeks to support respiratory and digestive health.  On the label they state: supercritical oregano supports respiratory, digestive, and immune system health.

Each soft gel capsule contains: 125mg Organic Oregano (O.vulgare) hydroethanolic extract (water/alcohol tincture) and 125 mg. Organic Oregano (O. vulgare) co2 extract with a minimum 38 mg total phenolic antioxidants.  Other ingredients include: Extra virgin olive oil and yellow beeswax. Capsule: Fish gelatin (Tilapia), water, vegetable glycerine, and carob. Contains: Fish

New Chapter recommends 1 soft gel capsule a day with food.

According to Gaia Herbs: Oil of Oregano contains antioxidant phytochemicals that support the body’s natural resistance.* Gaia Herbs’ supercritical CO2 extract of Oregano volatile oils contains potent phenols, including Carvacrol. These oils help support a healthy microbial environment in the intestines and initiate a healthy immune response.

The label on the bottle states that each capsule contains: Total Alcohol Free Extract Of: Oregano herb, (Mediterranean) Supercritical CO2 Extract (Origanum vulgare) 230 mg (460 mg for two capsules)* and Validated Full Spectrum Profile Carvacrol and Thymol 32 mg (64 mg for two capsules). Other ingredients include: soy lecithin and vegetable cellulose (capsule)

Gaia herbs recommends 1 capsule two times daily.  Internal use of essential oils should limited to a maximum of 4 weeks. In cases on continued application, allow 2 weeks break between courses for 1 week of use.

Gaia Herbs website:

SAFETY information:

Gaia Herbs listed the following: Do not take pure essential oil of Oregano internally. This product should be avoided in pregnancy and lactation. Excessively high doses may cause intestinal upset, diarrhea, frontal headache, tinnitus, anorexia, nervousness, and loss of taste. do not exceed the recommended dose. Use with caution if you are allergic to the Lamiaceae family (basil, sage, mint, hyssop, lavender, and others).  This herb may cause a systemic allergic reaction. If you experience fast or irregular breathing, itching, skin rash or hives, seek medical attention promptly.

Now lets have a look at Origanum vulgare in more depth. The oregano family (Labiatae/Lamiaceae) is widely known as possessing therapeutic properties (diaphoretic, carminative, antispasmodic, antiseptic, tonic), being used in the traditional medicine systems of many countries.


Botany of Origanum

The genus Origanum is characterized by a large morphological and chemical diversity. The genus includes 49 taxa (species, subspecies and varieties) divided into 10 sections with most of them having a very local distribution around the Mediterranean. For a complete overview of these tax see:

Origanum is a member of the mint family (Labiatae/Lamiaceae) and is characterized by tight cylindrical heads of sessile flowers called spikelets or spicules. Leaflike bracts cover the flowers just as shingles overlap on a roof. Plants in the genus Origanum are dwarf shrubs, or annual, biennial, or perennial herbs native to the Mediterranean region and central Asia. (Foster)

In this article we will be focusing on the species Origanum vulgare which is widely distributed throughout Europe, Asia and North Africa. Six subspecies have been recognized within O. vulgare based on differences in indumentum (covering of fine hairs or bristles), number of sessile glands on leaves, bracts and calyces, and in the size and color of bracts and flowers. These subspecies include:

  • O. vulgare L. subsp. vulgare
  • O. vulgare L. subsp. glandulosum Desfontaines) Ietswaart
  • O. vulgare L. subsp. gracile (Koch) Ietswaart
  • O. vulgare L. subsp. hirtum (Link) Ietswaart
  • O. vulgare L. subsp. viridulum (Martrin-Donos)Nyman
  • O. vulgare L. subsp. virens (Hoffmannsegg & Link) Ietswaart

Chemistry:  CO2 extract versus Essential oil

Distilled Essential oil: With such a large taxa diversity, it can also be expected therefore that there will be chemical variations within the essential oil extracted depending upon species used as well as subspecies. Indeed, in researching this article I found numerous differences in chemistry of O. vulgare essential oil depending not only on subspecies but also country of origin.

Some Origanum vulgare subspecies are rich in phenolic compounds: carvacrol (upwards of 22%) and/or thymol (upwards of 22%) although some have been shown to be rich in linalol (upwards of 28%), b-caryophyllene, y-muurolene, caryophyllene oxide and germacrene-d-4-ol.   (D’Antuono 2000)

One report on Origanum vulgare ssp. hirtum showed the following:  Essential oils obtained from inflorescences of three Origanum vulgare L.ssp. hirtum (Link) Ietswaart samples, growing wild in different locations in Campania (Southern Italy), were analysed. Three chemotypes were found: the first, with a prevalence of carvacrol/thymol; the second, characterized by the prevalence of thymol/alpha-terpineol; the third, featuring a prevalence of linalyl acetate and linalool. (DeMartino et. al.)

It would be incredibly valuable and almost imperative therefore when purchasing oregano essential oil to request the GC/MS report to have clarity of the exact chemical composition of the essential oil you are purchasing as this could alter its applications and safety concerns.

CO2 Extract: Main components trans-sabinene hydrate (45%), thymol (19-25%), carvacrol (7-8%). Other constituents include: p-cymene (1.78-5.7%), gamma-terpinene, cis-sabinene, linalyl acetate, thymyl methyl ether, linalool, alpha-terpineol and 4-terpineol. (all components after p-cyemen were present at under 3%)  (Ocana-Fuentes et al.)

Hydroethanol extractions: Tinctures
Hydroethanol extractions utilize a combination of alcohol and water to extract the medicinal principles from the plant material.  Oregano hydroethanol extract contains the powerful antioxidant, antiviral, antibacterial, anti-inflammatory compound: rosmarinic acid and the flavone apigenin.

Developing an understanding of Oregano’s therapeutic potential

Oxidative Stress and ROS
The excessive generation of molecules called free radicals can result in a state called ‘oxidative stress’. A free radical is an atom, molecule, or compound that is highly unstable because of its atomic or molecular structure (i.e. the distribution of electrons within the molecule). As a result, free radials are very reactive as they attempt to pair up with other molecules, atoms, or even individual electrons to create stable compounds. (Wu and Cederbaum)

An important class of oxygen-containing free radicals are called ‘reactive oxygen species’ or ROS. ROS compounds form naturally as part of the metabolic processes in the human body and typically cells have several protective mechanisms to prevent ROS formation or to detoxify these free radicals (antioxidant activity). An imbalance between ROS (free radicals) and antioxidants in favor of ROS where ROS becomes higher is termed ‘oxidative stress’. (Sies) An excess production of ROS is considered harmful to human cells. (Wei, et al.)

A variety of factors can contribute to an increase in ROS production and/or a decrease in the level of or activity of naturally occurring antioxidants within the body. These factors include: environmental stimuli such as ionizing radiation from industry, excessive exposure to solar radiations or medical x-rays, ozone and nitrous oxide (primarily from auto exhaust), environmental toxins, and lifestyles stressors (cigarette smoking, excessive alcohol consumption).

Excessive ROS levels have been implicated in many of the major diseases of our time including: cardiovascular disease, atherosclerosis, various types of cancer, diabetes, neurodegenerative diseases (Parkinson’s disease and Alzheimer’s disease), radiation injury, toxicity of heavy metals, vitamin deficiency, inflammation (such as the destruction of joints and the synovial fluid that lubricates the joints), toxic effects of tobacco smoke, emphysema, and cataracts. (Wu and Cederbaum)

There’s quite a bit of research on ROS and antioxidants. Some pointing out that not all oxidative stress is bad and some may actually be necessary under certain conditions. However, this article is not about that so perhaps in another article we shall pursue this concept in more depth.

Antioxidant activity
According to the National Cancer Institute, antioxidants are substances that may protect cells from the damage caused by unstable molecules known as free radicals. Antioxidant compounds in food and spices play important roles as health-protecting factors. (Suhaj).

In addition to the beneficial effects of antioxidants on human health, some antioxidants are also used in food industry as preservatives for preventing or delaying the oxidation process. Indeed, interest in essential oils as valuable antioxidants is growing due to the negative impact of synthetic antioxidants on human and animal health. (Albano, et. al.)

Fruits and vegetables rich in antioxidants include: kale, spinach, brussels sprout, prunes, raisins, blueberries, blackberries, strawberries, raspberries, alfalfa sprouts, broccoli, beets, and many others.

With regards to Oregano, the 2 most sited active components, thymol and carvacrol, have proven antioxidant and antimicrobial activity. (Mastelic, J, et. al.)

Aqueous tea infusions from oregano, thyme and wild thyme represent a good source of the compounds with significant antioxidant activity.

A study by Kulisic et. al. confirmed that the oregano essential oil possess remarkable antioxidant properties. The antioxidant effect is due to the presence of thymol and carvacrol, but a possible synergistic effect among oxygen containing compounds can be suggested too. These results indicate that the oregano essential oil could be in use as potential resource of natural antioxidants for food industry so that it is interesting to examine its application as natural antioxidant additive in some final food products.


Antimicrobial activity
Origanum essential oil, which is used as a food flavoring agent, possesses a broad spectrum of in vitro antimicrobial activities attributed to the high content of phenolic derivatives such as carvacrol and thymol. (Manohar, et. al.)

Antibacterial activity

Thymus vulgaris and Origanum vulgare showed much stronger antibacterial potential than streptomycin. Thymol and carvacrol show strong antibacterial activity. This paper concluded that “Because of their very high specific activity essential oils (such as oregano and thyme *inserted by author) may also be used at low and non-toxic concentrations for the prevention and treatment of intestinal diseases in animals and humans caused by Salmonella, Listeria, and other bacterial species. (Sokovic,

Antifungal activity
Oregano oil, specifically Oreganol P73*, was found to completely inhibit the growth of Candida albicans in culture. The study demonstrated that origanum oil effectively inhibits the in vitro growth of C. albicans, a human yeast-like fungus which can cause both systemic and superficial infections in debilitated individuals. In addition the study showed that origanum oil directly inhibits germination and filament formation (the two phases required for tissue invasion) by C. albicans. The study concludes that origanum oil can act as a potent antifungal agent against C. albicans, and can function similar to antifungal antibiotics such as nystatin or amphotericin B.   Origanum oil is show to be both fungistatic and fungicidal to C. albicans, the human pathogenic yeast.  (Manohar, et. al.)

In another study by Cleff, et. al. the essential oil of oregano (Origanum vulgare), rich in 4-terpineol (47.95%), carvacrol (9.42%), thymol (8.42%) and alpha-terpineol (7.57%) was found to be an effective antifungal agent against Candida spp. in vitro. The authors state that O. vulgare may represent a good alternative for the treatment of candidiasis.

Antiparasitic activity
According to one study, 14 patients who tested positive for enteric parasites, Blastocystis hominis, Entamoeba hartmanni and Endolimax nana, were treated with 200mg of emulsified oil of Origanum vulgare three times a day. After 6 weeks of supplementation parasites were no longer detected in 10 patients while parasite scores decreased in another three subjects. Gastrointestinal symptoms improved in 7 of the 11 patients who tested positive for Blastocystis hominis.  These patients reported an amelioration of symptoms including bloating, GI cramping, alternating diarrhea and constipation and fatigue. (Force, et al)

Anti-inflammatory activity
Oregano co2 extracts show anti-inflammatory properties by (a) reducing the release of pro-inflammatory cytokines, and (b) increasing anti-inflammatory secretion in activated macrophages. These results suggest that oregano supercritical extracts could be used as novel options for treatment of chronic diseases based on inflammatory processes. (Ocana-Fuentes, et. al.)

Carvacrol research:
Carvacrol, the predominant monoterpene in many essential oils of Labiatae including Origanum, Satureja, Thymbra, Thymus, and Corydothymus has substantial antibacterial, antifungal, antihelmintic, insecticial, analgesic and antioxidant activities. (Koparal and Zeytinoglu)

Other Information:

According to the German Commission E (, who list Oregano as an unapproved herb: Oregano (the herb) is used for ailments and difficulties of the respiratory tract, coughing, bronchial catarrh, as an expectorant and for antispasmodic relief of coughing.  It is used for disturbances of the gastrointestinal tract, bloating, stimulation of gall excretion and digestion, and an appetite-stimulating and antispasmodic agent.  Oregano is also used for disorders and afflictions of the urinary tract, abdominal diseases, painful menstruation, as a diuretic, for arthritis, as a sedative and diaphoretic.   Oregano is also used in gargles and baths.  Since efficacy has not been documented, a therapeutic use of this herb cannot be recommended.


Oregano (Origanum vulgare) hosts a multitude of potential benefits for human health and indeed research supports the claims made by both New Chapter and Gaia Herbs for their respective oregano based products.  As for the question: is there a difference between making your own capsules with oregano essential oil and purchasing the supplements made by these companies: I would say yes. Due to the chemical variation found within the essential oil of Origanum vulgare it seems more prudent to purchase from respectable companies such as New Chapter or Gaia Herbs. Also, they are using the CO2 extract of Origanum vulgare which is rare in the market.

I don’t work for either of these companies so I don’t have a special interest in promoting them. I have great respect for both due to the quality of their products and the information they provide.  Or, if you really want to work with Origanum vulgare on your own terms, try using the herb and making a cup of tea!  From the little bit of research I reviewed on the aqueous extracts of O. vulgare, this can be just as powerful.

Recommended Sources for Oregano supplements

New Chapter: Oregano Force

Gaia Herbs


Albano S M, Lima A S, Miguel M G, Pedro L G, Barroso J G, and Figueiredo A C. Antioxidant, Anti-5-lipoxygenase and Antiacetylcholinesterase activities of essential oils and decoction waters of some aromatic plants. Rec. Nat. Prod. 6:1 (2011) 35-48.

Cleff M B, Meinerz A R, Xavier M, et al.  In Vitro Activity of Origanum vulgare essential oil against Candida species. Brazilian Journal of Microbiology (2010) 41: 116-123.

D’Antuono L F, Galletti G C, and Bocchini P. Variability of Essential Oil content and composition of Origanum vulgare L. populations from a north Mediterranean area (Liguria Region, Northern Italy). Annals of Botany 86:471-478, 2000.

De Martino L, De Feo, V, Formisano C, Mignola E, and Senatore F. Chemical composition and antimicrobial activity of the essential oils from three chemotypes of Origanum vulgare L. ssp. hirtum (Link) Ietswaart growing wild in Campania (Southern Italy). Molecules, 2009 Jul 27; 14(8):2735-46.

Force M, Sparks W S, Ronzio R. Inhibition of Enteric Parasites by Emulsified Oil of Oregano in vivo. Phytotherapy Research 14, 213-214 (2000).

Foster, S. (1997). Herbal Renaissance. Layton, UT: Gibbs Smith Publisher.

Koparal A Tansu and Zeytinoglu M. Effects of carvacrol on a human non-small cell lung cancer (NSCLC) cell line, A549. Cytotechnology 43:149-154, 2003.

Kulisica T, Radonicb A, Katalinicc V, Milosa, M. Use of different methods for testing antioxidative activity of oregano essential oil. Food Chemistry 85 (2004) 633–640

Manohar V, Ingram C, Gray J, Talpur NA, Echard BW, Bagchi D, and Preuss H G., Antifungal activities of origanum oil against Candida albicans. Molecular and Cellular Biochemistry 228: 111-117, 2001.

National Cancer Institute at NIH. FactSheet: Antioxidants and Cancer Preventionl. Downloaded on November 14, 2011 from:

Ocana-Fuentes A, Arranz-Gutierrez E., Senorans F, and Reglero G. Supercritical fluid extraction of oregano (Origanum vulgare) essential oils: Anti-inflammatory properties based on cytokine response on THP-1 macrophages. Food and Chemical Toxicology 48 (2010)1568-1575.

Padulosi, S. editor. 1997. Oregano. Promoting the conservation and use of underutilized and neglected crops. 14. Proceedings of the IPGRI International  Workshop on Oregano, 8-12 May, 1996. CIHEAM, Valenzano (Bari), Italy. Institute of Plant Genetics and Crop Plant Research, Gatersleben/International Plant Genetic Resources Institute, Rome, Italy.

Sies, H. Oxidative Stress: Oxidants and Antioxidants. Experimental Physiology (1997), 82,291-295.

Sokovic M, Marin P, Brkic D, van Griensven L.J.L.D. Chemical composition and Antibacterial activity of ten aromatic plants against human pathogenic bacteria. Food. 2007. Global Science books.

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*To learn more about P73: