Updated: Apr 20
Plant-derived oils are copiously touted to help every ailment. Science has an issue with that.
Samantha Brody is tall when she stands up on our Zoom call, and her wide cherub face displays an eternal enthusiasm. Her coiffed hair lays neatly across her shoulders as she puts a few drops of peppermint oil into a pregnant essential oil diffuser shaped like a teardrop. “My first experience with oils was not a great one,” she tells me. She pushes a button on the diffuser, and it glows purple and green and blue as a fine mist permeates the room. I can almost smell it. “I mixed up lavender oil with frankincense thinking it would help the sunspots on my hands. I didn’t dilute it and rubbed it into my skin. Big mistake.” The oil burned her skin, causing her hands to turn bright pink. Then her body absorbed the oil and she developed large rashes from head to toe. Only a doctor's visit, a shot of cortisone, and ten days of hydrating with water returned her to normal. “I confess, though, essential oils help me sleep. I swear by lavender oil.”
While Samantha’s initial experience with oils was troubling, it is one based on a lack of knowledge for the user, a common gaffe with essential oils. While the oils are plant-based and natural, the safety of any oil depends largely on the person using it, and with any plant product, these oils can contribute to skin irritation, respiratory symptoms, and even hormone-related issues. Despite those cautions, the essential oil market is now valued at $7.3 billion and is expected to reach $14.6 billion by 2026. Yet science seems to scoff at those numbers, as research is inconclusive as to how effective the oils are, and even if they are good for you.
Essential oils have been used for thousands of years in cosmetics, perfumes, and for therapeutic purposes by ancient cultures from Asia and India, as well as the Egyptians and Romans. Today, essential oils are used to add scent to cosmetics and cleaning products, and to flavor food and beverages. Companies such as doTERRA sell the more medicinal versions – small vials filled with different oils for everything from better sleep to acne – and the company claimed its revenue exceeded $1.7 billion in sales in 2020. Yet this medicinal form is a late trend in the United States, as many other countries have used oils for centuries.
Dilini Vethanayagam, an MD and associate professor of pulmonary medicine at the University of Alberta, says Western countries are simply late to the market. “I’m originally from South Asia, and alternative medicines are very popular there, but that’s over many decades of training,” she reminds us, as most consumers using essential oils don’t have PhDs in chemistry.
A Coping Mechanism
It has been theorized that people today – especially during a pandemic - are turning to essential oils because they are disappointed by Western medicine, and as a coping mechanism in anxious times. Writer Annaliese Griffin wrote in Quartz that it is especially true of women, since modern medicine and the tremulous U.S. healthcare system have failed them many times. “The medical system is even more terrible for women, whose experience of pain is routinely minimized by health practitioners. … Enter the wellness industry, which specializes in creating safe, welcoming, amber-lit spaces that make people feel cared for and relaxed, and which treat the female body as its default. … The problem is that the rest of the wellness industry hitches a ride on their coattails of compassion and competency, benefiting from the utter lack of warmth found in mainstream medical treatment.” Her sentiment echoes the lack of empathy in the medical field and provides another form of attraction to essential oils to heal our woes.
Joe Schwarcz, director of McGill University’s Office for Science and Society, and known for demystifying chemistry, tells us that many plants’ compounds are volatile: “Some [are] destined to attract pollinators, others to ward off bugs that have the intention of making a tasty meal of the leaves. It is the volatile chemicals that are regarded as the plant’s essence and are the ones captured in the ‘essential oil.”
Many of the proclamations concerning essential oils are derived from studies demonstrating that the oils’ chemical compounds have certain benefits, for example, like tea tree oil, which has antibacterial and antifungal properties. The issue, says Schwarcz, is justifying the antibacterial properties to say it can cure your acne. It’s a leap to suggest oils can cure or treat medical conditions. To add to the muddy water, some claims are based on studies where essential oils were tested on rats or other animals rather than humans, or studies that were inconclusive, and of course, results indicating a placebo effect.
Schwarcz says that distributors in the essential oil market often make suspicious claims to drive sales. “Some of the people the company has snared with its promises of wealth through multi-level marketing end up making a bevy of claims about essential oils helping with cancer, autism, Alzheimer’s disease, mononucleosis, and arthritis,” he says.
As with other complementary and alternative medicines (CAM), the essential oil market is unregulated. Just a few years ago, the Food and Drug Administration issued a warning to essential oil marketer Young Livings. They concluded the company’s websites and social media accounts were mislabeling their products as drugs even though they were not approved as such. The company was marketing their products as cures, treatments, and preventions for everything from viruses to Parkinson’s, all of which were unfounded.
The Sensory System
Some recent studies demonstrate there’s no convincing evidence that aromatherapy can help hypertension, anxiety, depression, pain, or symptoms of dementia. Schwarcz says that studies shown to prove the benefits of essential oils are not reliable, due to plain genetics and brain chemistry. “The scent of lavender may have a calming effect in some people and help with sleep, but it can cause headaches in others,” he says. And this highlights the complicated views on the benefits of essential oils.
Pam Dalton, of the Monell Chemical Senses Center, says that while scents may be calming to people, “they likely aren’t working due to any pharmacological or biological effect, [but] rather a sensory/psychological effect.” You may enjoy the scent of mint because it makes you feel more alert when it stimulates a nerve that allows you to perceive exhilaration (or not).
There are valid data suggesting that oils may be beneficial, and PubMed defines them like this: "Aromatherapy uses plant materials and aromatic plant oils, including essential oils, and other aromatic compounds for the purpose of altering one's mood, cognitive, psychological, or physical well-being." There are ongoing studies for the oils as a natural treatment for stress, anxiety, and even for symptom management in cancer patients. Yet many of the studies are run by the large essential oil companies to try and counter-balance statements like this one from the National Advertising Division (NAD), which claimed false advertising in the oils.
A study in 1990 demonstrated that inhaling peppermint essential oil enhanced alertness, focus, and concentration, ingesting it, however, did not. Yet another one confirmed that smelling peppermint enhanced the accuracy of memory.
The sensory system is a tricky one. Smells often trigger memories and even physical stimulations, so studies done with essential oils are easily skewed. The reactions to oils are mood-based changes, in that scents create expansive neurological events that probably cannot be explained – yet – by physical science. An entire gamut of subjective memories is connected to scents, even scents from childhood. Dalton is at work on a cancer project funded by an essential oil company, but she says she’s still skeptical. Most research looking at the benefits of aromatherapy on cancer patients as complementary to chemotherapy is a bit of a stretch, and as with other treatments, the results are mixed.
Then there are the hormonal caveats to using oils. Dr. Romy Block, board-certified endocrinologist and co-founder of Vous Vitamin, says essential oils may create endocrine disruptors that interfere with the natural production of hormones. "These chemicals can either lower or raise the normal hormone levels in the body," Dr. Block says, "causing disruption of development, reproductive changes or even interference with the immune system."
There's not enough evidence yet, Dr. Block says, but a series of essential oils were linked to hormone-related health complications. Lavender oil, for example, shows an association with early breast development in girls. Two popular oils, lavender, and tea tree are shown to lead to a condition called prepubertal gynecomastia (abnormal breast tissue growth) in boys.
Dr. Block advises against one of the most popular methods, diffusing lavender and tea tree oils, because of the potential complications, especially in children, teens, and even pets. The best strategy, she says, is to consult with your health care provider before you diffuse these oils. Most essential oils are generally considered safe to inhale or apply topically, yet not diluted properly they can cause different reactions in different people, as they did for Samantha.
Vethanayagam, whose practice focuses on allergies, says ingesting oils is probably safe in small quantities. “The lungs are very sensitive, but the stomach goes through many processes to take out the bad stuff,” she says. Yet not all oils are the same quality, and some are not even meant to be ingested because of that. Only the best, high-quality oils should be ingested, and most of the poorer ones say not to ingest on the label.
The Power Of Scent
Essential oils have a long history of medicinal use, but the science on them remains inconclusive. Yet that science is complicated by the power of scent and the varied reactions to applying them topically or using them in a diffuser. One thing is certain, essential oils offer comfort to many. “If the smell of lavender relaxes you for whatever reason, sniff it at bedtime when you find it difficult to disengage,” Dalton says. “If the smell of wintergreen makes you feel more energized, take a whiff when you’re heading off for a run on the treadmill.”
As we go to end our Zoom call, my new friend Samantha is touting the benefits of the peppermint oil she is diffusing. “You know? It just gives me that blanketed feeling of a hug that never ends.”