Caroline Wallace combines two of her passions—science writing and complementary and alternative medicine, along with her knowledge of DoTERRA Essential Oils.
Caroline Wallace combines two of her passions—science writing and complementary and alternative medicine, along with her knowledge of DoTERRA Essential Oils.

Oregano (Origanum vulgare) EO

Anyone who likes Italian cuisine is awfully familiar with oregano. But did you know that the uses of oregano extend way beyond the kitchen?

I had to take a hiatus from blog posts to focus on some other business aspects. Now, I am back to deliver weekly posts so you can learn about the scientific studies that have been done on natural products.

Oregano is a purple flowering perennial herb in the mint family. There are different varieties of oregano plants. Wild versus cultivated plants have different amounts of the active compounds. Additionally, there are different amounts of these active compounds depending upon where oregano is grown. If you want to use oregano essential oil (EO) in a therapeutic way, it is important to get it from a reliable source so it has the best amount of active compounds. The essential oil is steam distilled from the leaves of the oregano plant.

The main active compounds in oregano are carvacrol, thymol, and terpenes.

One of the neat things about all EOs is that they are made of bioactive molecules in liquid form. This means that they can interact with the cells in our bodies. Also, because they are oil-based, they can actually get inside our cells. Water soluble medications cannot get inside our cells.

WebMD states that oregano is used for respiratory tract disorders, GI disorders, intestinal parasites, colds and flus, and even as an insect repellent. Oregano essential oil is considered “possibly effective” for high cholesterol and intestinal parasites, but there is insufficient evidence for the other claims. There are many claims that Oregano EO has antibacterial, antifungal, anti-parasitic, antiviral, and immune-stimulant properties. Keep reading to learn more!

For this research-based overview I used the PubMed search term “Origanum vulgare”, which came up with 1,353 articles. Filtering for clinical trials came up with 32 articles. Next, I will highlight the most convincing studies.

Anti-oxidant and Anti-inflammatory Potential of Oregano EO

A 2017 review summarizes the biological activity of Oreiganum vulgare EO. The most convincing studies in this review have shown antioxidant and anti-inflammatory capacity in cell culture conditions.

These studies give an idea of some of the beneficial activity of oregano EO. An antioxidant is any compound that stops the process of oxidation in cells. Everything in our body is a delicate balance! Oxidation is a natural process that causes damage to cell membranes. Antioxidants block this damage. Similarly, inflammation is a normal process – too much is damaging and can lead to chronic diseases. Anti-inflammatory products reduce inflammation to protect our cells.

A recent study looked at the effect of oregano essential oil on human skin cells. Researchers damaged the skin cells in cell culture models and then treated them with oregano EO.  They found that oregano EO had anti-oxidant and anti-inflammatory effects which helped heal the cells. The skin cells that were treated with the oregano EO had less signs of damage than the cells that were not treated (control group).

A 2020 review goes more in-depth by summarizing potential anti-proliferative, anti-cancer, anti-diabetic, anti-hyperlipidemic (cholesterol lowering), anti-obesity, renoprotective (good for the kidneys), anti-inflammatory, cardioprotective (good for the heart), and insecticidal properties.

Oregano EO Anti-bacterial Properties

Several studies this year have looked at the antibacterial properties of oregano EO. All of these studies were done in cell culture, which is a good way to look at the biological activities of compounds.

Oregano EO from Chile inhibited the growth of several strains of pathogenic (disease causing) bacteria, include bacteria associated with food poisoning. A study from Columbia (South America) looked at 15 different types of essential oils and their effects on pathogenic E. coli and MRSA. Thymol and carvacrol compounds, which are found in several different EOs, were the main compounds that reduced the bacterial functions. These two studies best highlight the antibacterial activity of the key compounds in oregano EO.

Oregano EO Anti-viral Properties

There is early evidence that oregano EO has anti-viral properties. A 2014 study compared whole oregano EO and carvacrol, one of the main compounds in oregano EO. The researchers tested the two products on mouse norovirus, which is similar to human norovirus (stomach bug). They found that both whole oregano EO and carvacrol significantly lowered the infectivity of the virus in just 15 minutes. This means that the virus was less able to infect other cells! Carvacrol was able to completely inactivate the mouse norovirus in just 1 hour.

A 2020 study showed that oregano EO and carvacrol in particular inhibit HIV-1 entry into target cells. If a virus cannot enter a cell, then it cannot infect the cell. The study also tested other viruses such as Hepatitis C, Zika, and H1N1 (a strain of the flu). Oregano EO did not appear to effect those viruses.

Other Uses of Oregano EO

I was surprised to see that oregano essential oil has been tested for a variety of uses besides what I mentioned above. For example, one research group in Morocco discovered that the EO improved sperm motility in petri dishes. Since the oil has terpenoids and antioxidants there is the potential that it could be an additive for medically-assisted reproduction. Please note that there is no evidence that taking it will help with infertility!!

Oregano EO compounds have been found to reduce inflammation and microbes in the intestines. In 2012, the active compound carvacrol was shown to reduce inflammation and ulcers in the stomach in a mouse model.

Interestingly, oregano EO is being tested in the poultry and pork industries for both reducing harmful bacterial and improving the meat quality. I will not be going into this aspect since it is outside the scope of the blog, but to me it is exciting to see research in this area. Additionally, oregano EO is being tested as a food additive due to its antimicrobial and antioxidant properties.

Final Thoughts

As you can see above, oregano EO is likely effective for a wide variety of purposes. However, it is challenging to compare findings from the current studies since the active compound concentrations vary depending upon the EO source. Many factors (soil, geographical location, part of the plant used, extraction method, etc) influence the potency, purity, and thus effectiveness of oregano EO.

Despite these variations, the results from the many cell culture experiments are exciting! The cell culture experiments give indications of how something works, since that is harder to figure out inside something complex – such as a human.

Studies are also important to determine the safety of products. For example, oregano essential oil may have possible contraindications (a reason to not use it) during pregnancy, before surgery, and in diabetics. Additionally, it can interact with lithium medications.

The research on the antimicrobial activities of oregano EO is the most exciting to me. Antibiotic resistant infections are increasing and the generation of new classes of antibiotics has not kept up with the need. Oregano EO is one example of how the medical field may find more immediate solutions in natural products that already exist.

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Disclaimer: The content of this blog, Essentially Science, is for general information only. This blog is not to be used as a substitute for medical advice, diagnosis, or treatment of any health condition or problem. Any questions regarding your own health and the supplements that you use should be addressed to your own physician or other healthcare provider. Health-related information changes frequently and therefore information contained in this blog may be outdated, incomplete, or incorrect. Statements made about products have not been evaluated by the Food and Drug Administration.

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