When you think of oregano, what first comes to mind?
If you are a fan of either Greek or Italian food, you should almost certainly be picturing a fresh Greek salad of cucumbers, olives, onions, and feta cheese, with dried oregano sprinkled on top. On the other hand, if you love Italian pasta, you can probably already smell that pot of pasta sauce, with a generous handful of oregano, which is bubbling away on the stove.
Like many other culinary herbs and spices, such as curry and garlic, oregano has also been around for centuries as a medicinal herb for a wide variety of conditions and illnesses. What are some of these conditions, and how might oregano help?
Forms of oregano oil
In its medicinal form, oregano is usually available as oil, in either liquid or capsule form. The liquid oil can either be applied to the skin or taken it in oral form, depending upon the condition that is being treated. For applying it to the skin, it should be diluted at a ratio of one teaspoon of olive oil to one drop of oregano oil. If your patients are taking it under their tongue, the oil should be mixed with olive oil at a 1:1 ratio. The liquid should be dropped under the tongue, and held for three minutes, before being rinsed out with water.
Properties of oregano oil
There are three distinct active ingredients in oregano oil that appear to provide its health-beneficial properties:
Carvacrol: This phenol compound stops the growth of several different bacterial strains.
Rosmarinic acid: This is a very powerful antioxidant
Thymol: This is an antifungal that may also boost the immune system
Staphylococcus aureus is one of the most common bacterial strains. It can cause conditions such as food poisoning or certain skin conditions. A 2005 study published in the journal Toxicology Mechanisms and Methods studied the effect of oregano oil on lab mice that had been infected with Staphylococcus.1 Out of the group of 14 mice given oregano oil, six (43 %) survived the past 30 days, which was almost equivalent to the group of seven mice out of the 14 (50 percent) who received standard antibiotics.
A study in the 2001 issue of the Journal of Agricultural and Food Chemistry looked at the antioxidant levels (measured as oxygen radical absorbance capacity [ORAC] levels) and phenolic concentrations for 39 commonly used medicinal and culinary herbs.2
Overall, the culinary herbs had higher ORAC and phenolic concentrations than did the medicinal herbs. Three varieties of oregano had the highest phenolic and ORAC concentrations of all the tested herbs. The researchers thought this may have been due to oregano’s rosmarinic acid levels.2
Yeast is a type of fungus that is usually harmless but can result in a number of digestive, reproductive, and infectious issues if it becomes overgrown. A 2010 article in the Brazilian Journal of Microbiology examined the effectiveness of oregano oil on 16 different strains of Candida.3 It was found to be approximately as effective as medication and could be a useful alternative.
This research shows that oregano carries on the same tradition as several other herbs and spices. They all serve dual purposes as both a way to complement the flavor of food and as an effective medicinal alternative to pharmaceuticals to treat many illnesses.
Preuss HG, Echard B, Dadgar A, et al. (2005). Effects of essential oils and monolaurin on Staphylococcus aureus: In vitro and in vivo studies. Toxicology Mechanisms and Methods, 15(4), 279-285.
Zheng W, Wang SY. (2001) Antioxidant activity and phenolic compounds in selected herbs. Journal of Agricultural and Food Chemistry, 49(11), 5165-5170.
Cleff MB, Meinerz AR, Xavier M, et al. (2010). In vitro, activity of Origanum vulgare essential oil against Candida species. Brazilian Journal of Microbiology, 41(1), 116-123.
In traditional medicine, oregano has been used for respiratory conditions (i.e. asthma, bronchitis, cough), gastrointestinal (i.e. diarrhea, indigestions, stomachache), anti-bacterial, anti-inflammatory, menstrual disorders, and diabetes2–4. Greek oregano (Origanum vulgare) throughout the world is the most recognized herb as being authentic or original “oregano”5. This variety is often reported to be elevated in rosmarinic acid, a phytochemical first isolated from rosemary (Rosmarinus officinalis) in 1958 by the Italian Chemists Scarpati and Oreinte6. The benefits of oregano on human health have been associated and attributed to the phytochemicals found therein. Phytochemicals isolated from oregano represent a heterogeneous class of compounds generated during secondary metabolism with most not appearing to participate in essential metabolic functions7.
The Mediterranean diet has been recognized for its health-promoting benefits related to cardiovascular disease, stroke reduction, and cancer reduction8–11. In the Mediterranean region, the diet can vary, however, it typically consists of fruits, vegetables, nuts, legumes, moderate fish and poultry consumption, high polyunsaturated fats, and low consumption of red meat12, 13. Another important component of the Mediterranean diet includes the herb oregano (Origanum vulgare). This perennial herb has been suggested to have a variety of health-promoting properties ranging from anti-oxidant, anti-inflammatory, analgesic, and anti-microbial14–16. Interestingly, two attributes that have received significant attention include the antioxidant activity and anti-microbial activity of oregano with regard to enhancing food stability17, 18.
There is growing public concern among consumers regarding the addition of chemical additives to foods19. Specific examples include the use of synthetic antioxidants that have been routinely used to enhance the shelf life of various foods. In the USA, the meat and poultry industry has relied heavily on synthetic antioxidants including butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, and propyl gallate, as well as tocopherols to prevent lipid and protein oxidation20–22. Consequently, researchers and food manufacturers are starting to shift from synthetic antioxidants to natural antioxidants. Oregano is one such herb that has been approved in the United States as a spice and natural flavor that can reduce oxidation. A recent study reported that oregano extract can maintain the physicochemical, and sensory acceptance, and reduce lipid and protein oxidation of lamb meat after frozen storage after 120 days23. In addition to maintaining the physical and chemical properties of the meat, there was also good sensory acceptance by consumers. These results suggest that oregano prepared using a variety of extraction methods may be a promising alternative to synthetic food preservatives.
In addition to the food preservation properties of oregano, there is compelling evidence that these phytochemicals display health-promoting properties related to the gastrointestinal tract1. Different extraction methods and solvents for each plant are detailed and the most abundant phytochemicals from each extract are outlined in this report. The anti-oxidant and anti-microbial properties of each herb are described along with specific food preservation studies. Finally, in vivo studies that show the impact of herb extracts on gastrointestinal health are outlined with significant findings. The goal of this review is to highlight the potential of these herb extracts to be used as natural food preservatives and to provide the benefit of improved GI health.
Oregano (Origanum vulgare)
Phytochemicals Oregano extract (OE) and oregano essential oil (OEO) have been studied for their bioactive properties, and an important step to understanding their mechanisms of action is the identification of major components (Table 1). The volatile aroma compounds in oregano OEO have been well characterized, with the majority of published articles on oregano focusing on essential oil. The most abundant compounds present in OEO include the diterpenes carvacrol and thymol, which have been extensively studied for their anti-bacterial and anti-oxidant properties. Studies have identified these compounds as comprising up to 92% of the total essential oil content24–26. Oregano extract has been produced using various extraction methods creating a variety of extracts that can vary in phytochemical composition. In a hydroalcoholic (80:20 methanol: water) extract, Martins et al. reported the major components to be luteolin 7-O-glucoside (20.88%), rosmarinic acid (14.62%), luteolin O-glucuronide (12.48%), and apigenin-7-O-glucuronide (5.78%)27. In sub- and supercritical CO2 extraction, the major phytochemicals identified include carvacrol, linalyl acetate, thymol, and cis-sabinene hydrate28. Other compounds identified in an ethanolic extract of oregano are 4-hydroxy-4-methyl-2-pentanone, rosmarinic acid, thymol, luteolin 7-O-glucoside, and caffeic acid29.