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We’re now well into a three-week journey of diving into the topic of essential oils’ hormonal effects. In this week’s Healing, Heath, and Wellness blog, I reviewed the basic principles that need to be understood when assessing how essential oils will impact reproductive health. I also provided all the links from the previous weeks’ articles including: the introduction to hormones and essential oils, my debunking of the latest endocrine scare with lavender and tea tree oils, takeaway points for safe use of essential oils for overall and endocrine health, and more. You can read it here.

In last weekend’s oily tip, I summarized findings that supported that clary sage oil has modulating effects on cellular signaling which can differ in individuals. Regardless of the scare-all-sclareol claims that it is based on this one, isolated, constituent, there is NO evidence that the synergism of clary sage essential oil is estrogenic. Like most essential oils, when used properly, this oil can bring about balance to the body in a holistic way.

This week, I wrapped up on the topic of clary sage oil by reviewing several human trials that demonstrated that this essential oil could support menopausal symptoms, alleviate menstrual discomfort, and be calming and soothing during labor. It was also found to be helpful to relax females undergoing urodynamic assessments for urinary incontinence (ouch!). (Note: The chemotype of clary sage in this study was high in linalyl acetate. Chemotype and quality determine the main constituents in the oil). Finally, I highlighted a rodent study that showed clary sage had mood modulating properties and it had antioxidant and microbe inhibiting properties in vitro. (Click here to read this article in full.)





After my completion of clary sage, I moved onto one of my favorite, culinary (proven safe for ingestion) essential oils. First, I listed the actions of fennel oil including:

  • Soothing to the digestive and respiratory systems
  • Inhibition of microbes
  • Acting as an antioxidant and a flavoring agent
  • Protection of rats’ livers
  • Calming to mice’s brains
  • Promotion of healthy breast cells in petri dishes
  • Support for healthy milk production in nursing women
  • An antispasmodic for uterine contractions in pre-menstrual rodents (Rats get PMS too!)
  • The antitumoral effect in cancer cell lines

One of the most important points to remember for all proclaimed “hormonal essential oils” is that petri dish studies and/or trials with isolated compounds have different effects than pure, quality essential oils. This is because all the constituents found within an essential oil have the property of synergism. This concept is especially important to keep in mind when it comes to fennel oil.

In my blog on the Five Safety and Usage Precautions of Fennel Oil, I discussed the importance of safety of ingestion. These included:

  • Proper Dosage
  • Quality of the essential oil
  • Taking the therapeutic essential oil vs. the isolated constituents
  • Understanding the estragole debate

The fourth point is what again emphasizes the difference between an essential oil’s effects in the body vs. isolated constituents.

Estragole, a compound found in fennel oil, was deemed toxic in rodent studies.

Here’s the big “but” though…

It was deemed safe in humans by the European Medicines Agency with the proper dose and usage.

One of my favorite reviews explains all the factors for determining how fennel will act in living, breathing Homo sapiens (humans) versus rodents. First, the detoxification enzymes involved in breaking down the constituents have different capacities in rodents and people. Second, the compounds present in the essential oil will balance metabolism, biotransformation, and elimination of all its constituents, making potential toxicity less of a concern. These points contrast with studying the effect of one isolate.

Finally, determining the components found in the fennel oil, based on how it is harvested, the region of growth, distillation techniques, and its resultant chemotype, will determine the overall synergism of the essential oil. In other words, different compounds are present and vary in various company’s fennel oils. This will impact metabolism and excretion of fennel oil.

I go into full-out-geek-out on this in the video and some excerpts of these important points are at the end of this blog.

Here’s the point.

My goal is to show you that essential oils are complex. This is so you have an idea of the power of holistic actions of essential oils, the importance of smart use and dosage, and how essential oils bring balance.

In a few weeks, I’ll explore fennel oil more. Here’s some takeaways for use below.







Usage and Dosage

  1. Consider using a blend for hormonal health or clary sage alone for support with hormonal balance, mood, discomfort, and other symptoms in menopause or menstruation. Place one drop diluted in carrier oil over the belly or apply to the wrists and inhale a few times a day.
  2. My favorite use of fennel oil is a drop of it over my cooked veggies, but I’ve also been known to rub it on my belly as stated above.

Now, I want to hear from you!

Share with me your favorite uses of clary sage oil and fennel oil below!


Excerpts from “Can Estragole in Fennel Seed Decoctions Really Be Considered a Danger for Human Health? A Fennel Safety Update” (explained in video):

What Causes Differences in Constituents in Fennel

Many phytochemical researches have been conducted so far to investigate the chemical composition of fennel essential oil with different results: depending on the time of harvests, conservation, region, and area of cultivation. The major components of fennel are phenylpropanoid derivatives: trans-anethole and estragole (=??methyl chavicol), and then alpha-phellandrene, limonene, fenchone, and alpha-pinene [1720].

Essential oil composition depends upon internal and external factors affecting the plant such as genetic structures and ecological conditions; agricultural practices also have critical effects on yield and oil composition in the essential oil crops, although essential oil has some main components that can variate significantly according to the maturation period [21]. (source)


Metabolism and Biotransformation in Rodents Versus Humans

In rodents, estragole is metabolized by several pathways (including O-demethylation (to give chavicol), epoxidation of the double bond, 1?-hydroxilation, and oxidative degradation of the side chain to carboxylic acids). This is proceeded by initial metabolic hydroxylation via cytochrome P450 enzymes. Ultimately, the outcome is a carcinogen that is converted by sulfotransferases into an unstable compound which can lead liver tumors in rodents.

Before you freak out, there’s a difference between our four-legged creatures and people. It was reported that human liver cells have a high level of an enzyme that provides protection against these reactants (i.e., allylic epoxide hydrolase activity is seven to 10 times higher than that seen in rat liver).

The authors state, “Consideration of these issues (dose, administration form, and differences in metabolism between species) raises doubts about the conclusion that fennel seed can be “reasonably anticipated to be a human carcinogen” [44], It is clear that human and animal metabolism cannot be directly compared but we think data should deserve attention.” (source)


Synergism and Balancing Out “Toxicity”

“In humans estragole usually enters the body as a component of fennel tea, or as a food that has been seasoned with herb that contains many other substance like nevadensin, epigallocatechine, other flavonoids, and anethole [in essential oil], that have a protective role and so counterbalance to the possible effect of pure estragole.”  (source)

Evidence-based Complementary and Alternative Medicine?: eCAM. 2012;2012:860542. doi:10.1155/2012/860542


Many blessings from my heart to yours!

This material is for information purposes only and is not intended to diagnose, treat, or prescribe for any illness. You should check with your doctor regarding implementing any new strategies into your wellness regime. These statements have not been evaluated by the FDA. (Affiliation link.)

Disclaimer: This information is applicable ONLY for therapeutic quality essential oils. This information DOES NOT apply to essential oils that have not been tested for purity and standardized constituents. There is no quality control in the United States, and oils labeled as “100% pure” need only to contain 5% of the actual oil. The rest of the bottle can be filled with fillers and sometimes toxic ingredients that can irritate the skin. The studies are not based solely on a specific brand of an essential oil, unless stated. Please read the full study for more information.

Thanks Pixabay and iStock purchases.