A study of On Guard, a mixture of essential oils, showed that it reduced the infectivity of influenza virus in dog kidney cells in the lab; but that’s irrelevant to the question of whether the product has any clinical effect in humans.
Essential oils smell good, but the claims of health benefits are exaggerated.
I got an e-mail inquiry about the product On Guard™. It is a blend of five essential oils (wild orange, clove, cinnamon, eucalyptus, and rosemary) sold by the multilevel marketing (MLM) company DōTERRA. My correspondent had read my article about that company and its products, and she was skeptical. She said “A pilot told me he has used On Guard™ for years and it seems to ward off colds/flus for him but that is only a personal testimonial and I wanted to do more research before I purchased/used.” She sent me a link to a published study of On Guard™. She was impressed that it seemed to take an objective research approach with no hidden agenda (not paid for by DōTERRA) but she didn’t feel qualified to evaluate it and she wanted to know what I thought about the study.
I read the study. I was not impressed. It was an in vitro study in dog kidney cells and had no relevance to human use of the product. As I reviewed it, I thought of some simple questions a layman could ask to decide whether a study supported use of a product like this.
The full text of the study is available online. The title is “Protective essential oil attenuates influenza virus infection: An in vitro study in MDCK cells.” They grew influenza virus in cell cultures of dog kidney cells. One group was incubated with On Guard™ and a control group was incubated with canola oil. They did various tests to evaluate the effects, including fluorescent focus assay, cell viability analysis, hemagglutinin titration, flow cytometry analysis and confocal microscopy of IAV binding and internalization, relative end-point RT-PCR, and immunoblotting for viral NS1 protein. You don’t need to understand what all those mean; I don’t either. Essentially, they found that the number of particles of influenza virus was significantly reduced by incubation with On Guard™: by 40% for a 1:6000 dilution and by 90% for a 1:4000 dilution. After establishing that it worked to weaken the infectivity of the virus, they did more tests to try to understand how it worked.
Assuming their conclusions were valid, so what? On Guard™ works to reduce the number of viral particles released by infected dog kidney cells in the lab, but it is not marketed to make dog kidney cells less infectious, it is marketed for humans to use. The authors commented:
The lack of toxicity and potent specific viral inhibitory activity suggest essential oil may be helpful as a possible antiviral drug for control and treatment of influenza virus infection. It could potentially be used as a non-toxic way to cleanse surfaces, or dispersed to eliminate aerosolized virus particles in confined areas. Since the oil is currently used as a food supplement, oral administration, once the pharmacokinetics are determined, may provide therapeutic benefit during infection.
Please note the qualifiers “suggest,” “possible,” “potentially,” “may.” This is nothing but idle speculation. There is nothing in the study to show that any of these uses are feasible. The study didn’t attempt to investigate whether the product benefits humans in any way when used as intended by its marketers. The study is worthless except as a suggestion for further research.
The DōTERRA website claims these primary benefits for On Guard™:
- Supports healthy immune and respiratory function
- Protects against environmental and seasonal threats
- Supports the body’s natural antioxidant defenses
- Promotes healthy circulation
- Energizing and uplifting aroma
These claims are flagged with the usual FDA disclaimer that the product is not intended to diagnose, treat, cure, or prevent any disease. But it is clear from testimonials like that of my correspondent’s pilot friend that customers have been persuaded to believe it will protect them from infections like colds and flu. There is a video on the website that is strongly suggestive, and there is a statement that it is “an effective alternative to synthetic options.” They have to be careful not to make any statements that the FDA and the FTC might object to; but the multilevel distributors may very well be making more specific claims to potential customers in private, or at least persuading them with strong suggestions and personal testimonials.
It can be taken internally on a daily basis (diluting one drop in 4 ounces of liquid), added to water to use on surfaces in the home as a non-toxic cleaner, applied to the skin (1-2 drops to the desired area after diluting with a carrier oil to minimize skin sensitivity), and diffused (3-4 drops in a diffuser) to purify the air. I find it hard to imagine that such tiny amounts would have any significant effect.
They warn against contact with eyes, inner ears, and sensitive areas and against use during pregnancy. They recommend avoiding sunlight or UV rays for up to 12 hours after applying to the skin. The company charges $42.67 for a dropper bottle containing 15 cc. (That’s only one tablespoonful.) It’s no longer sold only by MLM. You can buy it directly from the company online and from other online sources. Amazon sells it for $36.16.
Essential oils: The evidence is skimpy
Many people find aromatherapy enjoyable. The good smells are reason enough to use essential oils for relaxation and enjoyment. But there is little justification for using them to improve health. There are many health claims for essential oils, for instance in Dr. Axe’s Essential Oils Guide. Dr. Axe is a naturopath/chiropractor who claims essential oils are useful for everything from healing broken bones to preventing brain tumors, and he claims there is scientific evidence. But the evidence from scientific studies is skimpy, preliminary, or non-existent. The Skeptoid website has criticized the exaggerated claims for these oils, citing DōTERRA as a bad example.
Questions anyone can ask
When someone not well-versed in scientific research is contemplating purchasing a product that is allegedly supported by a scientific study, here are some questions anyone can ask:
- Was the study done on the actual product as sold, or just on one or more of its ingredients?
- Was there a control group?
- Was it a clinical study in humans, or just a study in animals or in cell cultures in a lab?
- Did it show meaningful clinical benefits like reduced incidence of infections, or did it just show surrogate measures like changes in lab tests?
- Did the study show that the product works for humans when used as you would use it if you bought it?
If my correspondent had read the abstract of the study with these questions in mind, I think she might have realized on her own that the study did not provide a reason for her to buy the product.
This article was originally published in the Science-Based Medicine Blog.