Updated: Apr 16, 2020
As promised in my last blog, I just have to share this observation I found from Nicholas Culpeper - I will be referring to him a lot as he has a fabulous way of describing things. As to Basil, it is a little long, but well worth it -
"This is the herb which all authors are together by the ears about, and rail at one another (like lawyers). Galen and Dioscorides hold it not fitting to be taken inwardly; and Chrysippus rails at it with downright Billingsgate rhetoric; Pliny, and the Arabian physicians, defend it....
away to Dr. Reason went I, who told me it was an herb of Mars, and under the scorpion, and, perhaps therefore called basilican, and it is no marvel if it carry a kind of virulent quality with it. Being applied to the place bitten by venomous beasts, or stung by a wasp or hornet, it speedily draws the poison to it. Every like draws his like. Mizaldus affirms, that being laid to rot in horse-dung, it will breed venomous beasts. Hilarius, a French physician, affirms upon his own knowledge, that an acquaintance of his, by common smelling to it, had a scorpion bred in his brain. Something is the matter this herb and rue will not grow together, no, nor near one another; and we know rue is as great an enemy to poison as any that grows.
To conclude. It expelleth both birth and after-birth; and as it helps the deficiency of Venus in one kind, so it spoils all her actions in another. I dare write no more of it."
Well! Strong words indeed, and not to get 'together by the ears' about it, but does modern-day research back up this rather ominous view of one of the most commonly used herbs in existence? (Not the scorpion-in-the-brain bit).
Just to clarify, as with all things in the plant kingdom, there are many different species of the species Ocimum basilicum alone (Ron Guba suggests this is possibly as high as 150 different types), this blog is dealing with the two types supplied by Essential Therapeutics - Tropical Basil and Sweet Basil.
I can see myself just from the difference in popularity of the two, that Sweet Basil is the more preferred oil, and this makes sense as practitioners need to err on the side of caution. As we all know, the methyl chavicol that is in Tropical Basil oil is known as being carcinogenic. It is true that it is also a skin irritant, so Sue Clarke states that "linalool (as in Sweet Basil) has an almost identical molecular formula (to methyl chavicol) and is considered much safer". Sweet Basil is an excellent therapeutic oil, and it is most certainly not my intention to say otherwise. However, I would like to look at the issues around 'Tropical' Basil oil. There is a lot of contention around this oil, and whether it is safe to use in aromatherapy, so should it have a place at all?
The carcinogenic effect of methyl chavicol (also called estragole) was noted when tested on rats and mice, injected in large quantities (0.5g per 1 kilo of body weight, per day). In human terms, this would be the equivalent of a 70kg human consuming 50ml of basil oil a day. Simply put, lower doses did not show this carcinogenic effect.
NOT simply put - and I know I said I would not get technical in these blogs, but in this case, to get the full picture, it cannot be avoided - it is not actually the methyl chavicol itself that causes the damage to the cells, but by compounds that form as the body 'digests' the original compound for excretion - which is then further metabolised into two other compounds, which can cause mutations to cell growth. At lower doses in humans, this is formed in only tiny amounts, and in fact metabolises into the safe compound, hydroxy-allylbenzene. (This information can be found in studies referenced below - just a few of many- and are cited by both Ron Guba and Robert Tisserand). Sue Clarke states that "high doses are potentially carcinogenic, but very low doses are not, since they are readily detoxified".
Now I'm certainly not a chemist, and caution is never a bad thing - but nor am I saying to ingest large quantities of pure methyl chavicol. While it is understood that this was for scientific research purposes on a single constituent, it doesn't need to be said that this dose would not be encountered in normal topical aromatherapeutic practice. For one thing, as with any essential oil treatment, it is not intended for long-term, high-dosage use (particularly not internal). And as Ron Guba reminds us, even when used topically - on humans - a small quantity of the oil used will always evaporate before it can be absorbed (unless covered by a non-permeable covering). So even at a therapeutic concentration (which would be low anyway, due to the awareness and training of the therapist, and the oil's skin-irritating nature), the client will not absorb the whole dose, and certainly not anywhere near the amounts discussed above.
We also need to take into account the very important, and often-overlooked fact in scientific testing, that herbs and essential oils are made up of many synergistic compounds. In several studies published on the National Cancer Institute website, basil (the whole herb) has been shown to have anti-carcinogenic properties. Tisserand and Young state "research has been published demonstrating that basil herb contains anticarcinogenic substances that counter the potential toxicity of the two (rodent) carcinogens (estragole and methyleugenol), and is itself anticarcinogenic (Jeurissen et al 2008; Alhusainy et al 2010). Some basil essential oils have been also shown to have anticarcinogenic effects (Aruna & Sivaramakrishnan 1996; Manosroi et al 2005)". We know that the essential oil is a very different beast but this just goes to show the complexity of the chemistry involved.
It is no wonder Culpeper bowed out of the argument. Maybe he knew that Basil was a complex, seemingly contradictory herb and wouldn't take sides in his colleagues' debates.
So why would you use Tropical Basil oil instead of the Sweet? Ron Guba (founder of Essential Therapeutics) states that as well as being an exceptional antispasmodic, it has outstanding analgesic actions (such as with headaches) as well as notable effects for fatigue and depression, shock and fainting. According to Salvatore Battaglia, the stronger anti-microbial and antispasmodic actions are due to the higher amounts of methyl chavicol in Tropical Basil oil, yet should be used with caution. Tisserand and Young state that topical application of this type should not exceed 0.1%, and not to use this type at all during pregnancy. As Sweet Basil is much more gentle, is not a skin irritant, and already has a low, safer dose of methyl chavicol, it makes sense that it is a much easier and more practical oil to use. It all comes down to the condition of the patient and the skill and knowledge of the qualified aromatherapist, to prescribe whichever oil they feel is best to use for the treatment, in appropriate dosages and for an appropriate length of time, specific to each individual client. As Tisserand and Balacs state, "in practice one must steer a middle course, and use all the information available, both positive and negative". And always if there is any doubt, it would be best to use the safer option, especially as there is one available.
This is a prime example of needing to be a fully qualified aromatherapist before using essential oils. A lay-person would be very unlikely to know about the complex chemistry involved and would not go searching for clinical testing before using a particular oil on their friends, families or themselves, or know about appropriate dosages or consider time-factors, and the metabolising of essential oils through pretty important organs of the body. This is an example also of why the willy-nilly practice of ingesting oils that has become so wide-spread is such a cause for concern. Here with Basil oil we truly see the importance of proper training and regulation.
Battaglia, S. The Complete Guide to Aromatherapy, 3rd Ed, Vol. 1, 2018. Black Pepper Creative Pty Ltd.
Caddy, R. Essential Oils in Colour. 1997. Amberwood Publishing Ltd.
Clarke, S. Essential Chemistry for Safe Aromatherapy. 2002. Harcourt Publishers Ltd.
Culpeper's Complete Herbal. http://www.complete-herbal.com/completeherbal1814.htm
Guba, R. Essential News. Vol 18 June 2005.
National Cancer Institute. https://www.cancer.gov/
Taylor & Francis Online. https://www.tandfonline.com/doi/abs/10.3109/00498258709167414
Robert Tisserand, Rodney Young PhD, in Essential Oil Safety (Second Edition), 2014
Science Direct. https://www.sciencedirect.com/topics/medicine-and-dentistry/estragole