With an essential oil, it is important to consider the synergy of the components in the oil. However, to really understand some of the why and how of an essential oil we can look at specific chemical components found within the oil. Here we'll look at the essential oil component spotlight: (E)-Anethole.
Trans-anethole is a chemical constituent of the ether chemical family. It's also referred to as anise camphor and can be found on most GC/MS or GC/FID analysis as (E)-anethole.
This specific essential oil component is used widely in the food industry as a flavoring agent because it is thirteen times sweeter than sugar. It is currently listed with a GRAS status by the FDA for flavoring purposes. However, trans-anethole does have some potential safety concerns.
Safety & Therapeutic Properties:
With anything that carries a great potential to be helpful (i.e. healing), it can also carry a great potential to be damaging (toxic). For this reason, we will are going to look at a few safety concerns surrounding trans-anethole.
Trans-anethole does have a few toxicity concerns that include being hepatotoxic, genotoxic, and neurotoxic. These terms are defined as:
Hepatotoxic: Toxicity to the liver in high doses
Genotoxic: This means it can interfere with structure and function of the DNA, creating abnormal cell changes. This is very important to understand because if you have a medical condition like pregnancy, you could be risking the life of your unborn child by using essential oils high in this component. Neurotoxic: means it can have a toxic or destructive effect on you. Symptoms of this would include dizziness, headaches, nausea, blurry vision, seizures, and potentially coordination problems.
It is important to note that this specific component also prevents your blood platelets from clotting (anticoagulant1).
With safety in mind for essential oils, there are a few conditions that are contraindicated for all (A) or oral (O) routes. If you have the following medical conditions, it is best to avoid essential oils high in trans-anethole7:
Please note that essential oils that are contraindicated include more than 50% of (E)-anethole. There are approximately five essential oils that fall into this category.
Below are a few therapeutic properties that research studies have shown regarding Trans-anethole ((E)-anethole). Please keep in mind these are for the specific chemical component and may not be representative of the entire essential oil it is found in depending on the percentages shown in gas chromatography and mass spectronomy analysis.
Analgesic: (E)-Anethole is moderately analgesic, in both in vitro and in vivo tests2
Antifungal: anethole has been shown to exhibit synergistic antifungal activity against a budding yeast3 and candida6
Anti-inflammatory: (E)-Anethole blocks cellular responses induced by Tumor Necrosis Factor indicating an anti-inflammatory action4 (TNF is a chemical messenger that induces cell death. TNF is directed at "abnormal" cells to assist in preventing the formation of tumors.)
There was a study also that showed anethole to be a potential candidate in supporting the restoration of functional dyspepsia.5
It is important to recognize that many of these studies regarding trans-anethole are solely about the singular component, and not the essential oils that it if found in. One also needs to consider who or what the studies were tested on (animals, in vivo, or in vetro). While we can deduct certain findings and apply them to humans, essential oils offer a synergy that is much harder to define.
Just because the essential oil component trans-anethole is found in essential oils, it does not mean you should be leery of using it at all. Yes, there are safety concerns, BUT the essential oils that it is found in, even with high percentages, can be used safely for most individuals.
If you are using essential oils with a very high percentage of trans-anethole, it is important to consider the dose and the length of use. Most individuals can use essential oils high in this component for short term use and in low dilutions to avoid any potential risks.
Yoshioka M, Tamada TT (2005) Aromatic factors of anti-platelet aggregation in fennel oil. Biogenic Amines 19:89-96
Ghelardini C, Galeotti N, Mazzanti G (2001) Local anaesthetic activity of monoterpenes and phenylpropanes of essential oils. Planta Medica 67:564-566
Fujita K, Ishikura T, Jono Y, Yamaguchi Y, Ogita A, Kubo I, Tanaka (Feb 2017) Anethole potentiates dodecanol's fungicidal activity by reducing PDR5 expression in budding yeast. Biochim Biophys Acta. 477-484
Fujita K, Kubo I (2004) Potentiation of fungicidal activities of trans-anethole against Saccharomyces cerevisiae under hypoxic conditions. Journal of Bioscience & Bioengineering 98:490-492
Asano T, Aida S, Suemasu S, Mizushima T (Mar 2016) Anethole restores delayed gastric emptying and impaired gastric accommodation in rodents. Biochem Biophys Res Commun. 472(1):125-30
Piras A, Falconieri D, Porcedda S, Marongiu B, Gonçalves MJ, Cavaleiro C, Salgueiro L (2014) Supercritical CO₂ extraction of volatile oils from Sardinian Foeniculum vulgare ssp. vulgare (Apiaceae): chemical composition and biological activity. Nat Prod Res. 28(21):1819-25
Tisserand, Young (2014) Essential Oil Safety, 2nd Edition. Churchill Livingstone.