Good science is always about asking questions and testing a hypothesis. This is how our society learns and grows with new innovation and progress. However, if researchers hold a bias of how an experiment or search of literature should go, the interpretation of results may not be accurate and we could miss great discoveries! Herein lays the glory and pitfalls of evidence-based medicine.
When I was first introduced to “snake oil” over 13 years ago, I was very skeptical. The fact that I experienced results in spite of my closed mind sent me to study how these plant secondary metabolites interacted with my biochemistry.
I learned that photosynthesis produces primary metabolites (proteins, carbohydrates, lipids, and chlorophyll) in plants. These allow the plants to live. However, in order for the plants to stay healthy and survive, their secondary metabolites are essential. Just as these “survival constituents” in essential oils, which include polyphenols, phenylproponoids, and terpenoids, contribute to plants’ immune defenses, these same compounds have been extensively studied and shown to exhibit wellness benefits for humans as well.
So, why the “lovers” and “haters?”
Unfortunately, there’s a bit of schism in essential oil science, research, and reviews. For example, there’s a disagreement of quality standards and schools or application.
Therefore, several issues can arise with the study of mechanisms of action of essential oils that can skew conclusions. Here’s some examples:
- A study uses a “commercial preparation” filled with synthetic fillers and comes to a conclusion on essential oils that are inaccurate.
- A study doesn’t take into account a plant’s chemotype and predominant secondary metabolites.
- Someone who isn’t aware of the intricacies of the various metabolites and the synergism of its properties could get confused with the long list of actions of a single essential oil. (Meaning, they think we are “all living on planet crazy!”)
Therefore, I’ve compiled a few of my thoughts on how I view the science of essential oils. This was sparked by one of my genius nutrition colleague’s question.
1. I agree with some essential oil critics regarding certain oil sites that are big on citing claims without substantiating them. This is why I study the science beyond the oils and herbs and list or include references from PubMed.
2. Oils aren’t inert, they should be used appropriately. The good news is that the safety level of quality oils is non-comparable to drugs. It’s important to note that most studies citing toxicity are not well done and usually consist of oils that are of unknown quality or of some unfortunate soul swallowing a whole bottle!
3. Of peppermint, fever, and basic biochemistry…
Some people ask me the references behind using peppermint to cool one down when the body is too hot. There is actually some basic science behind this, which is why if someone searches PubMed, they might get lost.
Menthol effects thermoreceptors in relationship to TRPM8. Oh, sorry, think “icy hot!”
Check out the full menthol section of this study if you want to geek out and explore the fascinating world of thermoreceptors.
I also found an interesting study on using menthol for cooling with cycling performance in 12 males in a tropical climate. The athletes “drank 190 mL of either aromatized (i.e., with 0.5 mL of menthol (5 gr/L)) or a non-aromatized beverage (neutral temperature: 23°C±0.1°C, cold: 3°C±0.1°C, or ice-slush: 1°C±0.7°C)… Cold water or ice-slush with menthol aroma seems to be the most effective beverage for endurance exercise in a tropical climate.”
4. Some studies test the wrong constituent in an oil or just haven’t found the one that exerts the effect. For example, rosemary essential oil has 1,8 cineole and carnosic acid.
You would want to look at carnosic acid as well as 1,8 cineole for brain, eye, and neurological effects when evaluating in vitro, in vivo, and human studies.
5. Tis’ the dose that is also important!
I look at some journal articles and sometimes giggle, as they truly impart the importance of appropriate dosage in human studies.
For example, this study tested two dosages using rosemary oil. One was 750mg of rosemary oil. This is .026 oz, or about .75 ml. A typical essential oil bottle will be 5ml (180 servings) or 15 ml (360 servings). Can you see why .2 oz or 6000 mg would be a little troublesome for treatment of memory? That’s over 180 servings! (5.9ml)
6. Sometimes scientists may disregard what someone testifies to and because there isn’t a research study, try to say that the whole category or modality is useless. For example, lavender may be touted for relief of head discomfort by many and Germans may agree, but some say there’s not a lot of research behind it on PubMed.
Well, what about the benefits of peppermint that has support for this issue and could have been missed if one stopped at lavender!
Final Conclusion:
I love essential oils and I enjoy diving into the research and learning how they work.
I think it’s important to have a critical eye whenever one is considering incorporating something into their wellness regime. Questions on validity of how something works is what makes science grow. It makes researchers ask the next question, and then validate or invalidate a claim.
Therefore, without knowing it, lovers and haters of oils or any modality are truly united in any issue. They are joined in their intention of learning if something, such as essential oils, works. As more questions are asked, more people will seek answers. This is the circle of life, philosophy, and science!
Disclaimer: This information is applicable ONLY for therapeutic quality essential oils. This information DOES NOT apply to essential oils that have not been assessed for quality, purity, and standardization of constituents.
Warning: There is no quality control in the United States for essential oils and oils labeled as “100% pure” need only contain 5% of the actual oil! The rest of the bottle can be filled with fillers and sometimes toxic ingredients that can irritate the skin and body.
This information is for information purposes only and is not intended to diagnose, treat, or prescribe for any illness.
Other References:
- Plant phenylpropanoids as emerging anti-inflammatory agents. Mini Rev Med Chem. 2011 Sep;11(10):823-35.
- Symposium on ‘Plants as animal foods: a case of catch 22?’: Antimicrobial properties of plant secondary metabolites. Proceedings of the Nutrition Society. (2004),63: 621–629.
- Combination of essential oils and antibiotics reduce antibiotic resistance in plasmid-conferred multidrug resistant bacteria. Phytomedicine. 2013 Jun 15;20(8-9):710-3. doi: 10.1016/j.phymed.2013.02.013. Epub 2013 Mar 26.
- Inhibition of methicillin-resistant Staphylococcus aureus (MRSA) by essential oils. Flavour and Fragrance Journal. 2008; 23: 444-449. DOI: 10.1002/ffj.1904
- Nelson, J. Selection of resistance to the essential oil of Melaleuca alternifolia in Staphylococcus aureus. J. Antimicrob Chemother. 2000; 45 (4): 549-550. doi: 10.1093/jac/45.4.549
- National Cancer Institute – PDQ Cancer Information Summaries. Aromatherapy and Essential Oils (PDQ®) Health Professional Version. Last Update: October 16, 2012. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0032645/
- Peir Hossein Koulivand, Maryam Khaleghi Ghadiri, Ali Gorji. Lavender and the Nervous System (Review Article). Evidence-Based Complementary and Alternative Medicine. Volume 2013 (2013), Article ID 681304, 10 pages. http://dx.doi.org/10.1155/2013/681304
- Susanna Stea, Alina Beraudi, & Dalila De Pasquale. Essential Oils for Complementary Treatment of Surgical Patients: State of the Art. Review Article-Evidence-Based Complementary and Alternative Medicine. 2014 (2014), Article ID 726341, 6 pages.
- CDC. Prescription Drug Overdose in the United States: Fact Sheet. October 17, 2014. http://www.cdc.gov/homeandrecreationalsafety/overdose/facts.html
Thank you istockphoto.com for the same cool photos!
