Not all lavender is the same
The chemistry behind a high-quality essential oil, and why it is decisive for aromatherapy
When people hear «lavender», most think of a familiar scent: floral, soft, fresh and calming. What we smell is the tip of a much larger interplay, because an essential oil is a complex mixture of many different natural molecules. Two bottles can both be labelled «lavender oil» and still differ in chemical composition, scent and quality. At Casa Cafaro we therefore ask of every oil what is in it, even if it smells impeccably of lavender.
Natural chemistry
The word «natural» often comes up with essential oils, and some people associate it with something free of chemistry. But nature too is full of chemistry. The lavender plant likewise forms its constituents through biochemical processes, and from these arises the mixture of volatile molecules that we later obtain as essential oil.
In Lavandula angustifolia, linalool and linalyl acetate are among the characteristic main constituents. Linalool is a monoterpene alcohol found in numerous plants, contributing substantially to their typical scent. Linalyl acetate belongs to the esters and, together with linalool, shapes the soft, floral scent profile of true lavender. A high-quality lavender oil also contains numerous other constituents, such as lavandulol, lavandulyl acetate, terpineols, ocimenes, 1,8-cineole, camphor and various sesquiterpenes. Scientific studies accordingly show differences between different lavender oils.
One might conclude from this that a good lavender must contain as much linalool and as much linalyl acetate as possible. That would be too simple. In a multi-component mixture, the constituents influence one another and together determine the chemical and aromatic profile of the oil. An essential oil can therefore only be judged by its whole profile. Reviews of lavender aromatherapy also point to the importance of composition, in particular the ratio of the main constituents.
True lavender and lavandin
If a product says «lavender oil», you first need to know which plant is meant, and many consumers are not even aware of this distinction. Lavandula angustifolia is what is known as true or fine lavender. Lavandin, Lavandula × intermedia, is a natural cross between Lavandula angustifolia and Lavandula latifolia and has its own properties and its own chemical profile.
Lavandin yields considerably more essential oil per cultivated area than true lavender. This higher yield makes it economically attractive for industrial production and is one reason why lavandin is often cheaper. So the price difference has little to do with quality; lavandin is a raw material in its own right with its own value. It becomes problematic when a product is sold as Lavandula angustifolia and actually contains lavandin or other constituents, because then the label is no longer correct.
For aromatherapy this is decisive, because there we work with plants and their chemical constituents. Linalool and linalyl acetate have been studied scientifically for various neurobiological mechanisms. There is research on lavender oil and its main constituents concerning possible influences on neuronal signalling pathways, including GABAergic mechanisms and voltage-gated calcium channels. Clinical and experimental work deals with possible effects of lavender oil on stress, anxiety and the nervous system. No promise of healing can be derived from this research, and the results depend among other things on the oil used, its composition and the type of application. Anyone using an oil with an altered composition may therefore be working with a different raw material from the one examined in the studies.
Analysis, adulteration and price
Our nose perceives the smallest differences in scents. An oil can nevertheless smell intensely of lavender and be composed differently from what is expected. One of the most important methods for examining essential oils is therefore GC/MS, gas chromatography coupled with mass spectrometry. Put simply, this procedure separates the volatile constituents of an oil from one another and identifies them. The result is a chemical profile that can be thought of as a fingerprint. From it, one can read which molecules are present in what order of magnitude, whether the profile matches the stated plant species, and whether there are unusual constituents or indications of adulteration. Scientific studies show that authentic Lavandula angustifolia oils can be distinguished in this way from lavandin and from products with synthetic additives.
Essential oils are adulterated in various ways. A high-quality raw material is stretched with other substances, cheaper lavandin is added to a product declared as Lavandula angustifolia, or synthetic single substances such as synthetic linalool or linalyl acetate are used to produce a desired chemical profile or a particular scent.
A study published in 2024 analysed 55 commercial lavender oils using GC-MS and GC-FID. Of the 51 samples labelled as Lavandula angustifolia, 51 % were classified as authentic. In the rest, the researchers found, among other things, lavandin, synthetic additives or combinations of these. The figures refer to this one sample set and show that the designation on the bottle alone does not prove authenticity.
We would never claim that every cheap oil is bad or every expensive one is high quality. Still, the price of a natural product has to come from somewhere economically. A raw material with considerably higher agricultural effort and considerably lower oil yield can hardly have the same cost structure as one with a very high yield, and with unusually low prices it is worth asking what was actually bought. Incidentally, in the study mentioned, more expensive products were also flagged as suspicious. Proof of quality therefore comes only from analysis.