Dr Sarah LoBisco, ND

Studies with Isolates Versus Synergistic Essential Oils

A recent badly extrapolated study spurred misleading headlines that two of the most beloved essential oils, lavender and tea tree, were possible endocrine disruptors.1-6 This began my now month-long rampage to reinstate the good name of essential oils and their safe use for hormonal and whole-body health.6  My goal continues to be to provide valid research, experts’ conclusions, and my own clinical experience to set the science straight.

So far, I’ve reviewed the basics on assessing studies and the importance of differentiating essential oils’ mechanisms in humans versus in petri dishes or rodents.6 I’ve also discussed why it is imperative in experiments to use quality, uncontaminated essential oils that are not polluted with plasticizers to provide valid results.6-9 Another pitfall I highlighted with in vitro (petri dish) studies included the use of testing trays that contain phthalates and endocrine disruptors which can escape into the experiment along with the essential oils. (source, source, source)7-9 This would be a classic case of the wrong witness (essential oils) versus the true villain (plastics) being convicted.

After understanding the basics on essential oils’ synergistic actions in humans, I started highlighting specific essential oils. First, I reported on the balancing properties of clary sage, including its use for menopausal, menstrual, and labor symptoms. I also explained why the essential oil is not “estrogenic.” These claims were mostly based on one isolated constituent, sclareol.10

Next, I began looking at the many benefits of fennel oil.11-12 Like clary sage oil, one compound found in fennel seemed to be its sticking point for full acceptance into the media’s good graces.  I reviewed in detail this estragole debate, the “bad” constituent in fennel oil, and how with proper use, dosage, and a high quality essential oil, the safety concern is unfounded.12-13 Similar to the igniting study of this series, many of the studies touting the toxicity of fennel oil are based on rodent and in vitro experiments with this one isolated compound, not the actual essential oil of fennel. (Are you sensing a theme in the literature with this yet?).

Most recently, I discussed the safety of sage essential oil and examined why the extrapolations based on the actions of few of its compounds were also misguided and not scientific.13-18 Furthermore, safety concerns based on several cases of overdosage with camphor or thujone are often mistakenly confused for effects of proper usage of the synergistic essential oil.13-21

In this series on Natural Path, I will provide another installment of “Is this____ oil estrogenic?” I will be highlighting sage essential oil and again emphasize the importance of considering the synergy within essential oils themselves when determining their overall effect.19-21 One study with lemongrass oil demonstrates this. The authors states:

Cymbopogon citratus (DC.) Stapf., commonly known as lemon grass and used, over many years, for medicinal purposes in West Africa, produces a volatile oil on steam extraction of its leaves. The antibacterial properties of the essential oil have been studied. These activities are shown in two of the three main components of the oil identified through chromatographic and mass spectrometric methods. While the alpha-citral (geranial) and beta-citral (neral) components individually elicit antibacterial action on gram-negative and gram-positive organisms, the third component, myrcene, did not show observable antibacterial activity on its own. However, myrcene provided enhanced activities when mixed with either of the other two main components identified.19

In another experiment combining in vitro and in vivo results, the authors sought to specifically assess the hormonal actions of essential oils. This study further demonstrated (1) essential oils have different effects then its individual compounds and (2) the variable results that occur with different cell cultures in petri dishes versus in rodents (a living organism). Below is an expert from the abstract:

At high concentrations, estrogenic activity was detected for citral (geranial and neral), geraniol, nerol and trans-anethole, while eugenol showed anti-estrogenic activity. Molecular graphics studies were undertaken to identify the possible mechanisms for the interaction of geranial, neral, geraniol, nerol and eugenol with the ligand-binding domain of the estrogen alpha-receptor, using the computer program HyperChem. Citral, geraniol, nerol and eugenol were also able to displace [(3)H]17beta-estradiol from isolated alpha- and beta-human estrogen receptors, but none of these compounds showed estrogenic or anti-estrogenic activity in the estrogen-responsive human cell line Ishikawa Var I at levels below their cytotoxic concentrations, and none showed activity in a yeast screen for androgenic and anti-androgenic activity. The potential in-vivo estrogenic effects of citral and geraniol were examined in ovariectomized mice, but neither compound showed any ability to stimulate the characteristic estrogenic responses of uterine hypertrophy or acute increase in uterine vascular permeability. These results show that very high concentrations of some commonly used essential oil constituents appear to have the potential to interact with estrogen receptors, although the biological significance of this is uncertain. (source)21


As you can see, claiming that essential oils are “estrogenic” or “disruptive” to any receptor, hormonal or otherwise, based on one or two compounds is not “scientific” … or rational. The complexity of plants and the innate healing potential of essential oils are not equal to the sum of its separate parts.

Essential oils have holistic effects. They are not a random arrangement of single compounds that manipulate receptor sites.11-12

Next, I will review the differences between extracts, herbs, and essential oils and studies assessing sage oil’s actions in vitro, in vivo, and in human trials.

Note: If you are new to essential oils, please review my safety resources guide here.


  1. LoBisco, S. The Continuation of the Lavender-Tea Tree-Hormone Controversy: In Defense of Essential Oils Synergy and Nature’s Wisdom. BreakFree Medicine Website. March 23, 2018. Available at: http://dr-lobisco.com/male-boobs-essential-oils-lavender-tea-tree-hormones-endocrine-disruption/
  2. Endocrine Society. Chemicals in lavender and tea tree oil appear to be hormone disruptors: Current Press Releases March 17, 2018 [Web page]. Endocrine Society Web site. https://www.endocrine.org/news-room/2018/chemicals-in-lavender-and-tea-tree-oil-appear-to-be-hormone-disruptors. Accessed March 28, 2018.
  3. Henley DV, Lipson N, Korach KS, Bloch CA. Prebubertal gynecomastia linked to lavender and tea tree oils. New England Journal of Medicine. 2007; 365(5): 479-485.
  4. Tisserand R. Lavender oil is not estrogenic [Web page]. Robert Tisserand Web site. http://roberttisserand.com/2013/02/lavender-oil-is-not-estrogenic/. Accessed March 28, 2018.
  5. Carson C, Tisserand R, Larkman, T. Lack of evidence that essential oils affect puberty. Reproductive Toxicology. January 2013; DOI: 10.1016/j.reprotox.2013.09.010.
  6. LoBisco, S. The Science to Set the Saga Straight…Hormonal Effects and Essential Oils: An Introduction. Healing, Health, and Wellness for the Body, Mind, and Spirit with Dr. Sarah. April 3, 2018. Available at: https://www.saratoga.com/healing-health-wellness/2018/04/the-science-to-set-the-saga-straight-hormonal-effects-and-essential-oils-an-introduction/
  7. Yang CZ, Yaniger SI, Jordan VC, Klein DJ, Bittner GD. Most Plastic Products Release Estrogenic Chemicals: A Potential Health Problem That Can Be Solved. Environmental Health Perspectives. 2011;119(7):989-996. doi:10.1289/ehp.1003220.
  8. Di Bella G, Saitta M, Lo Curto S, Salvo F, Licandro G, Dugo G. Production process contamination of citrus essential oils by plastic materials [abstract]. J Agric Food Chem[online]. 2001 Aug;49(8):3705-8. Available at: https://www.ncbi.nlm.nih.gov/pubmed/11513651
  9. Manayi A, Kurepaz-mahmoodabadi M, Gohari AR, Ajani Y, Saeidnia S. Presence of phthalate derivatives in the essential oils of a medicinal plant Achillea tenuifolia. DARU Journal of Pharmaceutical Sciences. 2014;22(1):78. doi:10.1186/s40199-014-0078-1.
  10. LoBisco, S. The Science to Set the Saga Straight…Hormonal Effects and Essential Oils. BreakFree Medicine Website. April 3, 2018. Available at: http://dr-lobisco.com/science-set-saga-straight-hormonal-effects-essential-oils-clary-sage-estrogen/
  11. LoBisco, S. Wrapping Up the Happy Hormonal Effects of Clary Sage Essential Oil and Getting a Taste of Fennel Oil: This Weekend’s Oily Tips. BreakFree Medicine Website. April 13, 2018. Available at: http://dr-lobisco.com/fennel-and-clary-sage-oil-for-healthy-hormones-debunking-isolated-claims/
  12. Gori L, Gallo E, Mascherini V, Mugelli A, Vannacci A, Firenzuoli F. Can Estragole in Fennel Seed Decoctions Really Be Considered a Danger for Human Health? A Fennel Safety Update. Evidence-based Complementary and Alternative Medicine : eCAM. 2012;2012:860542. doi:10.1155/2012/860542.
  13. LoBisco, S. The Safety of Sage Essential Oil Part I: Camphor, Thujone, “Toxicity” Oh My! Healing, Health, and Wellness for the Body, Mind, and Spirit with Dr. Sarah. May 1, 2018. Available at: https://www.saratoga.com/healing-health-wellness/2018/05/the-safety-of-sage-essential-oil-part-i-camphor-thujone-toxicity-oh-my/
  14. LoBisco, S. Sage Oil Safety Vindicated. BreakFree Medicine Website. May 4, 2018. Available at: http://dr-lobisco.com/sage-oil-safety-vindicated/
  15. Manoguerra AS, Erdman AR, Wax PM, Nelson LS, et al. American Association of Poison Control Centers. Camphor Poisoning: an evidence-based practice guideline for out-of-hospital management[abstract]. Clin Toxicol (Phila)[online]. 2006;44(4):357-70. Available at: https://www.ncbi.nlm.nih.gov/pubmed/16809137
  16. WebMD. Camphor. Vitamins & Supplements. WebMD Website. Available at: https://www.webmd.com/vitamins/ai/ingredientmono-709/camphor. Accessed May 7, 2018.
  17. Hazardous Substances Databank Number: 8144. alpha, beta-Thujone. Toxicology Database Research. Toxnet Website. Reviewed January 16, 2014. Available at: https://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+8144. Accessed May 7, 2018.
  18. Hamidpour M, Hamidpour R, Hamidpour S, Shahlari M. Chemistry, Pharmacology, and Medicinal Property of Sage (Salvia) to Prevent and Cure Illnesses such as Obesity, Diabetes, Depression, Dementia, Lupus, Autism, Heart Disease, and Cancer. Journal of Traditional and Complementary Medicine. 2014;4(2):82-88. doi:10.4103/2225-4110.130373.
  19. The School for Aromatic Studies. Synergism in essential oils and aromatherapy. Available at: https://aromaticstudies.com/synergism-in-essential-oils-and-aromatherapy/. Accessed May 7, 2018.
  1. Onawunmi, GO, Yisak WA, Ogunlana EO. Antibacterial constituents in the essential oil of Cymbopogon citratus [abstract]. J. Ethnopharmacol [online]. Dec;12(3):279-86. Available at: https://www.ncbi.nlm.nih.gov/pubmed/6442749.
  2. Howes MJ, Houghton PJ, Barlow DJ, Pocock VJ, Milligan SR. Assessment of estrogenic activity in some common essential oil constituents. J Pharm Pharmacol. 2002 Nov;54(11):1521-8.
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Sarah Lobisco, ND, is a graduate of the University of Bridgeport’s College of Naturopathic Medicine (UBCNM). She is licensed in Vermont as a naturopathic doctor and holds a Bachelor of Psychology from State University of New York at Geneseo.

Dr. LoBisco is a speaker on integrative health, has several publications, and has earned her certification in functional medicine. Dr. LoBisco currently incorporates her training as a naturopathic doctor and functional medicine practitioner through writing, researching, private practice, and through her independent contracting work for companies regarding supplements, nutraceuticals, essential oils, and medical foods.

Dr. LoBisco also enjoys continuing to educate and empower her readers through her blogs and social media. Her recent blog can be found at www.dr-lobisco.com.

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