Essential oils are made from the "essence" compounds of a plant or vegetation. The active compound in oregano oil, carvacrol, is responsible for a large portion of its purported health benefits. One of the most widely used essential oils, oregano oil could be a natural treatment for various medical conditions, and carvacrol has the potential to be an effective therapeutic treatment. But are these purported benefits just myth or is there scientific evidence to back up these claims?
TRUE Numerous peer-reviewed studies show that oregano oil (along with some other essential oils) is an inexpensive and effective antibacterial and antimicrobial agent, particularly against foodborne pathogens. In fact, carvacrol has been approved by the Food and Drug Administration (FDA) as a food additive and preservative to help prevent foodborne disease. Carvacrol can protect human foods from bacteria, viruses, fungi, parasites, and insect larvae. Specifically, it is effective in the fight against bacteria such as Staphylococci (staph), E. coli, Salmonella, Pseudomonas aeruginosa, Bacillus cereus, Aspergillus, Fusarium, and Listeria.
MOSTLY TRUE Multiple studies investigate the antiviral powers of oregano oil and carvacrol, and support their use in sanitization formulas. Most notably, carvacrol could to stop cell replication in antiviral medication-resistant herpes simplex (HSV-1), the common virus that causes cold sores. It was also effective at inhibiting the human respiratory syncytial virus (HRSV), which can lead to pneumonia in children and older adults. Research also shows that oregano oil and carvacrol can work against rotavirus and norovirus, which are responsible for the stomach flu. It is important to note that all these studies introduced carvacrol before inoculation, not after. That means it might help prevent a person from catching the virus, but it is unlikely to have much effect if a person already has a virus in their body.
SOMEWHAT TRUE Carvacrol, produced by the oregano plant to repel pests, can also keep bugs away from humans. One study found that oregano oil can be as effective as DEET at repelling ticks. Another study showed that 40% oregano oil was effective at repelling bed bugs. Maybe most importantly, a study in Natural Product Research found that carvacrol repels the yellow fever mosquito responsible for spreading the life-threatening dengue, Zika, and yellow fever viruses, among others. It's significant to note that these studies used a concentration of oregano oil four to 40 times higher than recommended for contact with the skin. Oregano oil itself is highly irritating to the skin, and increasing numbers of people report allergic contact dermatitis.
SOMEWHAT TRUE Many people report using oregano oil on minor cuts, scrapes, burns, and even acne with great success, particularly because of its antibacterial, antimicrobial, antifungal, and antiviral properties. The Journal of Drugs in Dermatology reports that oregano oil was more effective than petrolatum in healing post-surgical wounds, resulting in less infection, improved healing, and less scarring. However, researchers used a water-soluble oregano extract obtained after distilling the essential oil. Their extract did not contain skin-irritating properties like the essential oil, so patients did not experience any allergic or adverse reactions. Nutrition Today notes that oregano oil can especially irritate open or broken skin, and recommends only using a 1% oregano oil concentration on any open skin or wounds. People looking to use oregano oil to help treat minor cuts and burns should use a heavily diluted version.
PROMISING Multiple clinical studies have investigated carvacrol's cytotoxicity, or its ability to cause healthy or cancerous cells to die. In laboratory settings, scientists found that carvacrol destroys cancer cells and stops them from spreading, making it a potential preventative measure or treatment for oral, prostate, cervical, breast, colon, lung, and gastric cancers, as well as lymphoma, glioblastomas, carcinomas, and adenocarcinomas. To date, most research into the benefits of oregano oil has been conducted only using mice or in clinical laboratory settings. It is unclear whether oregano oil or carvacrol would have the same effects in humans.
MIGHT BE TRUE There has been only one randomized controlled trial suggesting oregano oil's potential as an anti-obesity treatment. Published in the Journal of Nutritional Biochemistry, the study included mice fed either a normal diet or a diet with carvacrol. The mice who had a diet with carvacrol saw reductions in body weight, weight gain, fat and liver weight, plasma and liver cholesterol, HDL-cholesterol, and fatty acids. These results, as well as carvacrol's known anti-inflammatory properties, highlight the compound's potential to help reduce the risk of diseases such as atherosclerosis, but there has been no research into the cardiovascular effects specifically.
MIGHT BE TRUE Animal studies provide some evidence of carvacrol's neuroprotective properties, its ability to protect brain cells from harmful chemicals or death. A chemical that shuts down cells of the brain responsible for memory and cognition causes Alzheimer's disease. Carvacrol appears to adhere to that chemical and cause it to malfunction; scientists are now investigating using carvacrol in the treatment of Alzheimer's disease. Additionally, carvacrol could have anti-anxiety properties without any negative effect on motor skills, making it a possibility for reducing the agitation experienced by many people with Alzheimer's and dementia.
MIGHT BE TRUE Multiple studies have investigated the anti-diabetic effects of oregano oil and carvacrol on rats and mice, with mixed results. One study reports significant decreases in blood sugar levels and considerable weight loss in rats with induced diabetes. In contrast, another study found no difference in diabetic markers like glucose, insulin, and cholesterol, but did note a reduction in liver damage.
TRUE Research from many credible medical journals supports oregano oil's potential as a therapeutic treatment for many conditions. However, the number of studies conducted thus far is small and have mostly used animal subjects. That being said, oregano oil has a large following and considerable body of anecdotal evidence behind it, and people may find it effective for them. Experts suggest using only highly-diluted oregano oil (1%) to avoid adverse reactions. Until more research is published, oregano oil should be used with caution. It is best to speak with a doctor first before starting any new herbal treatment.
FALSE Evidence supporting the health benefits of oregano oil and carvacrol is highly anecdotal and subjective. Additionally, there is limited research on the value of essential oils in general, and human trials have had mixed results. Furthermore, the manufacture and sale of essential oils are not regulated, and the FDA has not approved essential oils as treatments or cures for any disease or medical condition, only as food additives and preservatives.
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