Essential oil research—what’s it all about?

Aromatherapy and essential oils have a rich history of effectiveness, and thankfully due to the increased interest in the modality, there is now a growing body of evidence-based research into the field. Experimental scientific studies and research help us understand and advance our knowledge of essential oils, application and usage methods. But what does all the research, its methods and techniques mean? Let’s unpack some terminology associated with research.

Common research terminology

• In vitro

  In vitro is Latin for “in glass,” meaning the diagnostic treatments, scientific testing, and experiments are carried out in a sterile setting, like a test tube or petri dish. The conditions that exist inside a living organism cannot be replicated by petri dishes and test tubes, despite the fact that they offer controlled environments for in vitro testing.
  
  It is important to note that the results of in vitro testing do not always predict the response of a complete living individual; it is crucial to interpret the data with caution.
  
  Pharmaceutical research and fertility therapies are two examples of in vitro testing.

• In vivo

  In vivo is Latin meaning “among the living.” It describes the tests, methods, and experiments that scientists carry out in or on a complete live organism, such as a human, a lab animal, or a plant. Essentially, this means testing that could include animals as subjects.

• Ex vivo

  Ex vivo translates from Latin as “without a living body.” In this kind of testing or experiment, the living tissues are extracted straight from a living organism rather than being made artificially. The experiment is then carried out right away in a lab setting with barely any modification to the organism's natural environment. 

• In silico

  In silico is a newer term when it comes to research. According to Ekins et al. (2009), the term in silico is a modern-day term that means “experimentation performed by computer, and is related to the more commonly known biological terms in vivo and in vitro.” In short, it means “computer simulation.”
  
  In silico describes computational models that examine pharmacological hypotheses utilizing techniques including databases, data analysis tools, data mining, homology models, machine learning, pharmacophores, quantitative structure-activity connections, and network analysis tools. In vitro studies are generally conducted in conjunction with in silico approaches.

• Clinical

  A clinical study is a research project that uses participants, also known as volunteers, as human subjects; it aims to further medical understanding. Clinical trials, also known as interventional studies and observational studies, are the two main categories of clinical studies and investigations.
  
  Clinical research is defined by the National Institutes of Health (NIH) as a scientific inquiry that involves actual humans. Clinical research has only one objective, which is to ascertain whether a certain treatment protocol is an effective and reliable way to bring about positive change in people.
  
  The importance of clinical research cannot be underplayed. What happens in a petri dish (in vitro), in isolated cells (in vivo), or on a computer (in silico) are incomplete and accurate representations of what happens when we use essential oils on humans. The other types of research and studies influence clinical research, and do support the work of clinical studies, but they are not the full picture.

Examples of aromatherapy research papers

It is wonderful that a growing body of research is being conducted on essential oils using various methods, as it continues to legitimize their use and aromatherapy as a modality overall. But where does one find research on essential oils? A good place to start is PubMed. PubMed is a free search engine maintained by the National Institutes of Health. It accesses databases for references and abstracts on life sciences and biomedical topics. A quick search on PubMed for essential oils elicited thousands of results. It is important to note that it doesn’t give complete access to the full research, and in many cases it just shows research abstracts. Make sure you read the complete case research before citing it as a reference of essential oil efficacy or safety.

An example of a randomized clinical trial is The effect of music therapy and aromatherapy with chamomile-lavender essential oil on the anxiety of clinical nurses: A randomized and double-blind clinical trial (Zamanifar et al., 2020).

You can search for research information on essential oils, aromatherapy, carrier oils, CO₂ extracts, hydrosols, and absolutes. Be mindful of the search terms you use when you start looking. You may elicit different responses if you use say lavender essential oil as opposed to Lavandula angustifolia.

Why is it important to understand aromatherapy research?

Knowing the differences among these approaches to testing and research helps us to understand the applications and limitations of essential oils in the real world. We have seen many people post and share about some essential oil research, but when you delve a little deeper, the research is just an indication of further study that needs to occur, or sometimes it is misrepresented by parties with competing interests. The research also helps us determine the safety and efficacy of essential oils.

When looking at research papers, we need to look beyond the headline and the abstract. We need to look at the methodology used, we need to look at the authors and whether they have conflicting interests, and we need to look at what type of oil or extract was used (Latin name should be included)—what is an essential oil? Was it a chemical constituent of an essential oil? Was it a CO₂ subcritical or supercritical extract?

This is obviously not a complete list of what to look for, as you will learn more about these topics as you study with us at Essence of Thyme, but this gives you a good starting point when it comes to essential oil research.

The amount of research being conducted into essential oils, carrier oils, and aromatherapy is growing daily, and it is an exciting area of research for many, including us as practitioners and educators. It helps us all to keep abreast of the breadth and depth of this evolving modality. And isn’t that exciting?!

References

Ekins, S., Mestres, J., & Testa, B. (2007). In silico pharmacology for drug discovery: Methods for virtual ligand screening and profiling. British Journal of Pharmacology, 152(1), 9-20. https://doi.org/10.1038/sj.bjp.0707305 

(n.d.). National Institutes of Health (NIH). https://www.nih.gov 

Zamanifar, S., Bagheri-Saveh, M., Nezakati, A., Mohammadi, R., & Seidi, J. (2020). The effect of music therapy and aromatherapy with chamomile-lavender essential oil on the anxiety of clinical nurses: A randomized and double-blind clinical trial. Journal of Medicine and Life, 13(1), 87-93. https://doi.org/10.25122/jml-2019-0105 

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