Unfortunately there are many proposed uses for essential oils in popular culture that are based solely on how the herb for that oil has been historically used. Let us look at the logic of making such assumptions solely on the basis of chemistry. As we all know, everything ultimately boils down to chemistry!
It’s very important for people to understand that the essential oil makes up only a tiny minority of the overall chemistry of the plant that gets distilled. The EO is composed of the smallest, most volatile molecules in the plant that are not soluble in water, primarily terpenes and derivatives thereof. The herb, on the other hand, contains many other types of molecules, both water soluble and non-soluble. The real truth about plants and the molecules in them that are most useful to humans, is that the really good stuff, the really hard hitting chemically active parts of the plant that most effect humans ARE NOT IN THE ESSENTIAL OIL. Does this mean essential oils are not useful? Of course not. But most plant bio-actives, the really serious ones, are the molecules that are too large and too heavy to come over in a steam distillation process. Essential oils certainly have their therapeutic place, but they don’t contain the types of molecules that can do things like directly fight cancer for example, at least not in vivo (of course many essential oil molecules can destroy cancer cells if you put them in contact in a petri dish, but so will many synthetic aroma chemicals and that is a totally unrelated scenario than fighting cancer in the body). Essential oils are not drugs, but other heavier molecules in plants certainly can be, cannabis is a perfect example. The cannabis essential oil, while it has its own very nice therapeutic uses, contains no cannabinoids (THC, CBD, etc.) which are the real heavy hitters in terms of biological activity and are, in fact, natural drugs (change the actual physiology of the body). This is why one cannot get “high” from inhaling the vapors of diffusing or burning cannabis essential oil.
Because of the vast differences in the chemistry of the whole herb versus just the essential oil portion of a plant, one should NEVER take the properties of the herb and assume that the essential oil will have the same properties. This would literally be like saying “A nice juicy steak from a cow has a lot of great protein, but I don’t like meat so I am just going to collect the sweat from the cow and drink that to get all the protein I need.” Of course sweat does not contain any significant amount of protein, as it is mainly water, so this would be a preposterous notion. Obviously the real protein, the most useful stuff to our bodies, is in the meat of the cow. This does not mean that there can’t be some overlap between the essential oil and herbal medicine, we all know that smelling fresh lavender flowers can have a relaxing effect, just as the essential oil has a relaxing effect, this is because the lavender flower contains the essential oil and it’s the essential oil that you are smelling when you smell the flower. But I promise you, and please don't try this at home, you will have an entirely different experience if you eat 5 grams of lavender flower versus drinking 5 grams of lavender essential oil. In fact, the latter would not be a good idea at all!
So you might be asking, what options are available then if the medicinal use of the herb should not be ascribed to the essential oils? Well, if you really want some sort of concentrated extract that will the have herbal medicine properties of the plant in a more useable form, there are products available that would be more appropriate, such as CO2 total extracts. If you are not familiar with CO2 extracts then please see my previous note on the subject for more information, What are CO2 Extracts?. Going back to our cannabis example, it would only take a very small amount (1/10 of a gram) of a cannabis CO2 total that was extracted from a high THC strain to literally knock you on your, well...... you know, and you will likely feel the effects for more than 12 hours. Of course ingesting 0.1 gram of the essential oil would do basically nothing to you other than leave a very bitter taste and dissolve some of the mucous in your mouth leaving it dry (remember essential oils are very good organic solvents). The essential oil has its value, but has to be used in the appropriate manner, and not like the herb or the CO2 extract. In the case of cannabis essential oil, it is found that using the oil in conjunction with the CO2 extract, or even in conjunction with cannabinoid isolates, in vaping applications increases the overall effectiveness in both medicinal and recreational uses. Research has shown that the terpenes of he essential oil bind to the cannabinoids in ways to enhance the benefits, which has lead to extreme interest in cannabis essential oil as of late. Some refer to this as the “entourage effect.”
In summary, essential oils are beautiful products that can enhance our lives greatly, but we should be clear in our understanding of the limits of their uses. Essential oils are not drugs and they are not to be assumed to have the properties of the herbs from which they come. Everyone should do thorough research before using essential oils, herbs, and especially CO2 extracts as they are vastly more potent than the herb from which they come. Hopefully people will share this note with their friends who are using essential oils so that we can stop this age old myth from continuing to perpetuate.