Hi, I’m Wendy Zukerman.. You’re listening to Science Vs from Gimlet Media. The show that pits facts against fragrances…
On today’s show Essential Oils. This is our most requested show yet! Yes, you guys really want to know if there’s good science behind essential oils. And we were listening! So to find out if there is any scents in this…. we scoured through hundreds of academic papers … and yes there are so many scientific studies into essential oils…
Before the studies though… our first stop today is to talk to some true essential oil enthusiasts... to ask them what kind of powers they think are contained inside these little glass bottles... we sent our senior producer, Kaitlyn Sawrey to diffuse the situation…
KS: Hi Wendy… Yep I went on an essential oil adventure… it was the nicest smelling reporting trip I’ve been on as a reporter
It was this store in manhattan have these essential ols 101 nights, so they have new people come in and teach them about essential oils… I was like, probably a good place to start.
? Right now I’m smelling the Manhattan Musk
? Mmm that’s nice
KS oh that is nice
? Here’s wild lavender have we already smelled that one?
? Smells like Ahhh
WZ I’m imaging lots of dreamcatchers and...
KS: it’s not quite that crunchy. So it’s a narrow shore in the west village… with 100s of little brown bottles… and the class is run by this guy called Joe
<what is aromatherapy… art and practise and science of the use of essential oils>
KS: He’s a David Bowie fan, he’s wearing an awesome David Bowie tshirt,, hair goes down past his shoulders, working there for the past 17 years And there were soo many oils around, I wondered what his house looks like
JR it's a mess. in my bathroom i’ve got oils. Bedroom I’ve got oils. In living room there’s oils. And in the Closet a whole big boxes of all oils.>>>
He looks at them like a medicine cabinet, and he says they do special things. different oils do different things?
WZ: This is the key to essential oils: it’s not just nice smells… there’s something special in each oil?
KS Yeah, so each oil is coming from a different plant right, so they have different chemicals, So Joe gave me a bit of list of his favourite oils and what they can do
RJ if you put peppermint on your skin. It’s a Anesthetic. It’s great for pain…peppermint great for digestive issues. stimulating. Rosemary as far as stimulating your neurons your brains cells so it’s not something you want to mess around with before going to sleep, whereas lavender would be better at that time.
RJ there's a lot of science. these aren't just empty scents. they contain medicinal value
WZ: Ok… this is the kind of thing I get skeptical about
KS Surprise! Wendy’s skeptical.
WZ it’s like with all these things it’s like a panacea… oh this one’s for stomach this for head your toenail hurts, take this
KS that’s not a thing
WZ it sounds like classic snake oil…. !
KS: Yeah.. you know I hear that… it sounds like a lot of promises. But Joe did say this one thing to me that kind of made me go ...hm… maybe there is something here…
Much of our pharmacology today has come from plants…... aspirin came from Willow, and also comes from birch and wintergreen
KS: And Joe also says he has lots of research to back him up…
All science based, the chemistry involved in those oils, the biochemistry how it’s interacting with the body…
WZ: Okay so you spent a night hanging out with Joe and a bunch of number of other people who visited his shop…. where do you stand at the moment do you think there are unique qualities in essential oils?
KS: I wouldn’t rule it out. I wouldn’t rule it out. Because until we’ve done the digging, they are different kinds of chemicals why wouldn’t they have different effects. Maybe there is something to this. I’m open to it. So as a woman of science you should be open to it too. See where the evidence takes you.
WOAH!!
You are absolutely right… I’ve done no digging, only judgment, time to do some digging.
MUSIC POST
So after that chat with Kaity, we started going down the rabbit hole on this. And it turns out there’s a lot of research essential oils[1] And scientists have been studying them for decades! They’ve been looking at all kinds of stuff.[2],[3],[4]…[5],[6],[7],[8], like whether these oils can ease anxiety, or improve memory … some scientists are even looking at whether they can cure cancer… So what have they found?
Could essential oils really nature’s amazing medicine cabinet?
When it comes to essential oils there’s a lot of self care. But then there’s science.
AHHHHH
Science Vs essential oils is coming up, just after the break.
PRE ROLL
Welcome back. So today we’re looking at essential oils and whether they really work. Because there are tons of claims bouncing around online about health problems that essential oils can treat …
One of the most extreme claims is that essential oils can fight cancer. Websites written by supposed doctors claim… essential oils “halt cancer growth”[9] or quote “treat cancer at the cellular level.”[10][11] end quote And you can find people online doing personal testimonials and saying basically that essential oils cured their cancer[12]…
And these claims… mean lots of people coming into essential oil shops, like the one Joe works at… searching for answers …
Very sad They’re desperately looking for help for themselves or a loved one
KS You have people coming in regularly saying i heard this could help?
Yes, emailing, coming in>>
And these people point to the same kinds of studies to support their claims… studies showing essential oils stopping cancer from growing.. And the studies are real... some of them are even done by reputable universities but here’s the thing -- all these studies show essential oils shrinking cancer in petri dishes[13] [14] [15] or in rodents[16] [17] [18] [19] [20]. Not in humans.
And you should know… we’ve cured cancer in mice soooo many times with so many different chemicals… And they barely ever work[21] in humans. We found several trials looking at the effects of essential oils in HUMANS with cancer… and ? … They don’t do anything to shrink people’s tumours.[22][23] And can even give cancer patients nausea… [24] [25] Even Joe, who thinks essential oils can work for a lot of things … knows this cancer idea is bunk.
JR: There’s not proof that this is shrinking tumours.. That’s unconscionable hype that’s hurting a lot of desperate people that we deal with here just about everyday
Ok so that’s one the extreme claims out there about essential oils. And it’s basically[26] [27] [28] rubbish. But what about the idea that essential oils could help you feel more relaxed? Or improve your memory? Well here is where the science gets a lot more interesting…
*atmos knock knock hello hello nice to meet you hey lovely to meet you…
This is Dr Mark Moss and his cats - all four of them
MM: As soon as i get home meow meow
Mark is the head of psychology at Northumbria University in the UK.[29] He studies how we can improve our brains and memory … Mark got interested in essential oils... after a grad student had an idea … she wondered, could a particular oil make our brains work better?
MM she came to me and said do you know anything about rosemary. good for potatoes and lamb. But I don’t know anything else about it. And she said rosemary’s supposed to be good for improving your memory.
So he starts looking into it and realises that this has a long history …
MM I love this history… ancient greeks would wear rosemary when they were preparing for exams. [30] shakespeare wrote about it in hamlet when Ophelia says there’s rosemary that’s for remembrance.[31]
And Mark thought, if it's good enough for the Ancient Greeks, it's good enough for me! No, not really. But he started thinking well it is technically possible… that a smell could have an effect on your brain. It’s been shown with other chemicals. And here’s how it tends to work....
When you inhale chemicals they can go into your nose, into your lungs…and from there they can go into your bloodstream[32] and then into your noggin[33] [34] [35] . But if you’re a chemical… getting into the brain is pretty tough…
MM now the brain is rather more restrictive than access to the lungs WZ vip situation MM yeah quite a heavy doorman system the brain Mark I love this so much
That heavy doorman is a barrier between the brain and the rest of the body … it’s called the blood-brain barrier… it’s there to protect our brain from bacteria and other nasty stuff. But some chemicals do squeeze past the doorman … we’re not sure if many chemicals from essential oils can do this, but just the idea that it’s possible [36] [37],[38],[39],[40] ... does make Mark think that the idea behind essential oils isn’t crazy. And he wants to test it out to see if Rosemary can actually improve your memory...
So he set up this experiment….got almost 150 people to come into his lab… and made them do this memory test on a computer… while some got the smell of rosemary wafted into the room [41]. But he didn’t want them to know the smell was part of the experiment because he didn’t want to influence the results. So he figured out a way around it …
MM by, well, lying MM if the participant says oh there's a smell in here we say oh I don’t know what that’s about someone was in here earlier it’s got nothing to do with us.
For this memory test, the people in the study are sat down in front of a computer…and they’re given a list of words… noodle, keg, mitten, bull, cannon, pastry, sneeze.… and then they have to do a bunch of other tasks. 25 minutes later, the researchers ask them to recite the list of words … to see how many they remember. And find out if those who smelled rosemary did better ...
WZ what did you find MM we found rosemary improved people's long term memory.
Yeah![42] Rosemary helped the people in the study remember more words, on average, than the people who didn’t get the scent … Mark also found that people who inhaled the rosemary aroma said they felt more alert than those who didn’t.[43] And Mark has done a similar experiment in school kids.[44] And found the same thing.
MM it’s demonstrating that there is something going on when you're exposed to rosemary aroma-02
But before you shove your nose in some roasted potatoes… here’s something you should know,… … Mark’s results are tiny[45] [46] [47] … The people who got the Rosemary only remembered a tiny bit more than the other group -- not even a word more…And Mark totally acknowledges this.
MM the amount of evidence we have right now is not enough to jump off a cliff about.
MM The effects are typically quite small. Absolutely. MM essential oils are not magic bullets. It’s not oh i'm having difficulty sleeping get the lavender out out for the count. oh i'm having memory problems rosemary will help me remember the complete works of shakespeare. It’s not where it’s at. These are gentle effects,
For Mark though, even if Rosemary isn’t some blockbuster drug, it doesn’t mean essential oils couldn’t help some people.
these are mild effects. But I would argue that they are real effects… just because they're small doesn't mean they don’t potentially have inherent value for us.
Do you use essential oils?
MM no!
WZ what?
MM no it's my job. i do research because it's my job.
WZ but don’t you want better memory and to sleep better?
MM Well yeah I also a 6 pack but don’t want to go to the gym.
After the break, we continue scouring through the research on the hunt for an essential oil with a more powerful effect. And we actually find one.
BREAK
Welcome back, so we just heard that essential oils may be having an effect on our brains -- helping us to remember things. But the effects are very, very subtle. That was just for rosemary and memory though. There’s lots of claims out there about the powers of essential oils … lavender can help with sleep and anxiety, and peppermint can stimulate you - and reduce headaches.
But when we scoured the research searching for evidence that essential oils could help with all kinds of illnesses[48]: anxiety[49] [50] [51] [52] [53], depression[54] pain[55] [56], sleep[57], dementia[58],[59], and headaches… [60] There was no consistent evidence[61] that essential oils could help with any of this stuff. So, some studies would find an effect and others wouldn’t … and lots of times there are problems with the way the research is conducted… either the people in the study aren’t random…maybe they are already interested in the topic and are more likely to say it does have an impact[62] … and some studies are like the rosemary study we just told you about… they show effects but really tiny ones.. Like a study with only 15 people[63].
Amidst all of that, though… we did find one thing though. A convincing effect backed up by STRONG research.. But it has nothing to do with your brain. It’s this. Peppermint oil seems to be helpful for digestion[64]. Five separate clinical trials found this[65] [66] [67]. But it wasn’t diffusing the lovely scent of into your house… people were eating it, in these concentrated capsules.
So the clinical trials for essential oils… are very very underwhelming… And yet…there are hundreds… thousands… of people are buying them in droves[68] . They swear by them[69]. And it’s not just people who are out trying to sell these oils claiming all these benefits… there are lots of people who don’t have any financial stake in the success of essential oils are saying: these things work for me. So what is going on here… how can people feel better on essential oils… but it’s not showing up in the clinical trials? To walk us through it…
RH no no no zoey off the couch good girl ok i'm ready
We're interviewing Zoey-- the talking dog!!
You’re going to be on the internet!
No no, we’re interviewing Zoey’s human... Rachel Herz [Pron Hers]…
Off the couch off the couch
a cognitive neuroscientist at Brown University who researches smell[70]. She has written a book about the power of smell called The Scent of Desire[71],[72]..... Rachel believes that essential oils can work… but not because they’re having a specific effect on our brain, but because of something very different. To explain to us, she told us this story about when she was little.
Rachel was about 5 years old...it was a summer day and she was in the backseat of her parent’s car...
RAnd all of a sudden there was a scent. my mother said oh i love that smell. i love mommy i thought it was a great smell. a couple of days later i said-04
Rachel still remembers this beautiful smell…
RH so for me... i describe it as a cross between garlic and chocolate. RH a couple of years later i said oh i love that smell my friends on the playground said ewww that's so gross you’re so weird.
Why were they so mean?... Well... cos Rachel was smelling a skunk. And she says the reason she likes the smell of skunks… is because her mom, who she loves, told her it was a nice smell. And, so she associated it with this pleasant memory of driving through the countryside on a summer day. And to take this back to essential oils … Rachel says the same thing is going on when people respond to them… It's not about some unique chemical inside a plant… it’s about the fact that someone told them that when they smell it they’ll feel a certain thing and then they do.
RH So you walk to an aromatherapy shop and the purveyor has all their essential oils out for you… this one destress this one relax focus destress revitalising and the fact that they are telling you this is 98% of the effect.
WZ So is this just the placebo effect?
RH Yes basically this is just a placebo effect
Now, the fact that essential oils could be completely placebo doesn’t mean that people don’t feel effects. Placebos are real. Being told that something may have an impact on your body can actually cause an impact on your body. Placebos so powerful that practically every clinical trial must control for them[73].
So how can Rachel be so sure that what’s happening with essential oils is the placebo effect at work? Well… she points to this rather curious… experiment [74] on 90 people. Some were given something to smell. And the researcher told them:
She just said there’s a scent that’s going to be a smell that is either people think is going to be stimulating or relaxing and calming…
And all through the experiment she measured their heart rate… Here’s what she found… When people were told the scent was going to be stimulating!! Their heart rate up… and it even made them sweat a little… When others were told that the smell was going to be relaxing. Well? Their heart rate tended to go down… And guess what? … They were both given the same oil: lavender.
So it had nothing to with the lavender it was what they had been told. this is why we think lavender is relaxing. learned it's relaxing. But it could just as easily be marketed as being stimulating
WZ when you read that study what were you thinking?
RH great! this vindicates….
I’m sorry this dog… Zoey easy…
This really vindicates… There isn’t something magical or inherent to the smell…This is about learning. not drug like effect-01
This is just one study. But We found scores of others suggesting that essential oils don’t do anything above a placebo… [75],[76],[77],[78].[79] [80][81]…[82],[83].
Exactly RH if lavender makes you feel good. I am not disputing that one bit, that feeling is completely real. It’s just where that feeling comes from that I want to make a point, so I believe aromatherapy works, but not for the reasons aromatherapy proponents claim it works
So when it comes to essential oils… do they stack up?
There are lots of claims that each essential oil has some unique quality… that can cure… so many things… but the evidence in humans... is underwhelming. … Unless you have digestive problems.
But basically, from the research we have right now… it seems more likely that if you’re feeling good because you use essential oils… it’s the placebo effect… And you know what… essential oils probably aren’t going to hurt you… so if you love putting some rosemary oil on while you’re studying for an exam… go for it…
KS: Hey Wendy… I have something to tell you. Going to out myself to the science vs community
WZ: WHAT?!
KS: I use EOs, lavender… orange… eucalyptus…
WZ why
KS because they’re nice
WZ: But Kaity you know these chemicals aren’t special…
KS: So what
WZ what are you using them for
KS I have a diffuser, I put them in my bath. It’s nice i feel good.
WZ: But these companies, parading around showing that there is concrete in science here! There coming into our turf. And for the most part their science is rubbish That’s annoying. Sometimes they even where lab coats…
KS Wendy, you seem very agitated … i think I know what you need? you need some lavender in your bath.
WZ stop it.
KS Try it, it might work for you.
That’s Science Vs Essential OIls
CREDITS
This episode was produced by Meryl Horn, with help from me Wendy Zukerman, Rose Rimler and Odelia Rubin. Our senior producer is Kaitlyn Sawrey. We’re edited by Blythe Terrell and Caitlin Kenney. Fact checking by Michelle Harris and Rose Rimler. Mix and sound design by Emma Munger. Music by Emma Munger and Bobby Lord. A huge thanks to all the researchers we got in touch with for this episode - including Ryan Dalton, Elaine Elisabetsky, Belinda Hornby, Diane McKay, and Thomas Cleland. Also thanks to the Zukerman Family and Joseph Lavelle Wilson!
Next Week we’re tackling veganism: do you need to eat meat and dairy to be healthy?
I f*in hate vegans
Like they expect my bones to turn to dust but no I’m still here walking around
I’m Wendy Zukerman, fact you next time.
*bath atmos and pan flutes fade up*
KS: Wendy you don’t know what you’re missing out on.
[2] Hospital https://www.ncbi.nlm.nih.gov/pubmed/9439271
[3] Study of 4 patients with sleeping problems in Hospital, lavender helped them sleep
[4] Dentist: https://www.researchgate.net/profile/Johann_Lehrner/publication/7664124_Ambient_odors_of_orange_and_Lavender_reduce_anxiety_and_improve_mood_in_a_dental_office/links/59fc2611a6fdcca1f29321d4/Ambient-odors-of-orange-and-Lavender-reduce-anxiety-and-improve-mood-in-a-dental-office.pdf
[5] Classroom/ Teachers https://www.hindawi.com/journals/ecam/2013/853809/
[7] Published articles have described the use of aromatherapy in specific hospital settings such as cancer wards, hospices, and other areas where patients are critically ill and require palliative care for pain, nausea, lymphedema,[46,47] generalized stress, anxiety,[48] and depression.[49]
[10] First – essential oils for cancer research suggests that oils can help prevent and treat cancer at the cellular level
[11] https://draxe.com/frankincense-oil-cancer/ Frankincense Benefits “Contains potential cancer-fighting properties”
[15] Menthol derived from
M. piperita appears to affect cytosolic arylamine Nacetyltransferase (NAT) activity in the human liver tumor cell line J5 differentially dependent on dose (Lin et al., 2001);
[16] Mice fed peppermint beginning 2 weeks after DMBA (at the time of Croton oil application) showed a significant reduction in the cumulative number of papillomas compared with mice either topically treated with peppermint during the 2 weeks between DMBA and Croton oil application or untreated mice. … These results suggest that the chemopreventive effect of peppermint on skin papillomas is most active during the promotional stage of carcinogenesis.
[17] https://pdfs.semanticscholar.org/cf27/8b9e72dfc6fb003d0559d607a44b21e87520.pdf Interestingly, intratumoral injection of EOT significantly reduced solid tumor development. Indeed, by the 30th day of repeated EOT treatment, the tumor volumes of the animals were 2.00 ± 0.27, 1.35 ± 0.20, and 0.85 ± 0.18 cm3 after injection with 10, 30, or 50 µL per 72 h (six times), respectively, as opposed to 3.88 ± 0.50 cm3 for the control animals. This tumoricidal effect was associated with a marked decrease of mouse mortality.
[18] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4070586/ [table 2 and 3 for summary of all in vitro and in vivo experiments]
[20] https://link.springer.com/article/10.1007%2Fs10637-009-9345-2 The incidence of gastric tumours in MNNG treated rats was 100% with a mean tumour burden of 274.38 mm3 and tumour multiplicity of 1.16 per rat. Multiple friable chalky white nodules with small cauliflower-like growth were seen in the forestomach of MNNG treated animals. Administration of eugenol decreased the tumour incidence to 16.66 per cent with a tumour burden of 14.78 mm3 and tumour multiplicity of 0.16 per rat.
[21] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3902221/ However, the average rate of successful translation from animal models to clinical cancer trials is less than 8%.
[22] https://onlinelibrary.wiley.com/doi/10.1002/ptr.2072 Perillyl alcohol (POH) [which is the a naturally occurring monoterpene derived from the essential oils of various botanicals including lavender, peppermint, cherries, sage, and lemongrass. Unfortunately, despite evidence of anticancer activity of POH in vitro, oral administration has not yet shown any clinical antitumor activity (Bailey et al., 2004; Azzoli et al., 2003; Liu et al., 2003; Meadows et al., 2002; Howard et al., 2002).
[23] Ihttps://www.mskcc.org/cancer-care/integrative-medicine/herbs/perillyl-alcohol] In human studies, oral POH did not benefit patients with prostate (10), ovarian (7), or breast cancers (14).
[24] https://link.springer.com/article/10.1007/s00280-003-0599-7 A phase I trial of perillyl alcohol in patients with advanced solid tumors: No antitumor activity was observed. The dose-limiting toxicities in this trial were nausea and vomiting, encountered in all patients at the highest dose level.
[25] https://link.springer.com/article/10.1023%2FA%3A1025437115182 Phase II trial of perillyl alcohol (NSC 641066) administered daily in patients with metastatic androgen independent prostate cancer. Main toxicity included grade 1–2 gastrointestinal intolerance (nausea/vomiting in 60% of the patients) and fatigue (47%). One patient developed a grade 4 hypokalemia that was felt likely attributable to the drug. Perillyl alcohol administered at this dose and formulation did not have any objective clinical activity in this patient population.
[26] https://link.springer.com/article/10.1007%2Fs00432-010-0873-0 Patients with primary recurrent GBM treated with POH showed 5.9 months survival advantage compared with 2.3 months mean survival of historical control group (Fig. 1a), [limitation: doesn’t seem like the controls were great weren’t actually included in the experiment, but just taken from a database-“The present study aimed to analyze the clinical efficacy of intranasal POH administration upon overall survival rate of patients with recurrent malignant glioma in comparison with control untreated GBM patients (historical controls) with similar retrieved clinical database but not included in the POH protocol.”
[27] https://www.mskcc.org/cancer-care/integrative-medicine/herbs/perillyl-alcohol#references-15 “More recent preliminary studies found intranasal POH delivery in patients with malignant gliomas to be well-tolerated and effective, with one study reporting tumor size regression (15), and another reporting increased overall survival and no side effects after long-term use (24). Confirmatory studies are needed”.The report showing tumor size regression: https://www.sciencedirect.com/science/article/abs/pii/S0090301907008336?via%3Dihub seems to be a case study , and there’s critical commentary at the end of the article: https://www.sciencedirect.com/science/article/abs/pii/S0090301907008464?via%3Dihub “However, aside from a few illustrative case reports, there are no statistics provided in this paper, so the conclusion of clinical efficacy in this trial is premature.”
[28] No studies in the published peer-reviewed literature discuss aromatherapy as a treatment for cancer specifically.
[30] https://www.sciencedirect.com/science/article/pii/B9780857090393500256?via%3Dihub Greeks, who wore rosemary wreaths in their hair, also believed that rosemary strengthened the brain and enhanced memory. In Egypt, the herb was buried with the pharaohs.
[31] https://www.tandfonline.com/doi/abs/10.1080/00207450390161903 Lavender essential oil is widely considered to possess sedat- ing properties, and rosemary is believed to be arousing and has been linked to memory at least as far back as the writings of Shakespeare (Hamlet Act4, scene5).
There’s rosemary, that’s for remembrance; pray you, love, remember. And there is pansies, that’s for thoughts.
[32] https://journals.sagepub.com/doi/10.1177/2045125312436573 The results reported here support the proposal that 1,8-cineole would be detectable in the blood serum of healthy human volunteers following inhalation of the aroma of rosemary essential oil.
[33] One study from the 1990s found that rubbing lavendar on skin also made it get into the bloodstream https://pdfs.semanticscholar.org/3530/6465958d8e35e36e7933fa57ba134fe4f9b3.pdf
[34] Chemically, plant essential oils are heterogeneous mixtures (often hundreds in total) of, amongst others, the lipophilic volatile hydrocarbon monoterpenoids (grouped by their different functional groups into, for example, alcohols, oxides, phenols and the less volatile
[35] the current authors favour a third possible mechanism. The pharmacological mechanism suggests
that active volatile compounds enter the blood stream via the nasal or lung mucosa
[36] Yes, I agree. Although it is what I believe it is what is happening and all the evidence suggests it is possible, there is no definitive study that has expressly assessed it. (email from Mark Moss)
[37] https://link.springer.com/article/10.1007%2Fs10886-005-8393-0 Considering that cineole is a small lipophilic molecule and will readily cross the blood–brain barrier… [but this paper just cites extreme examples of eucalyptus oil poisoning]
[38] http://www.gpb.sav.sk/SI-2009/33.pdf injecting camphor essential oil or 1,8- cineole induced seizures in rats (supposed evidence that it’s getting to the brain....)
[39] https://www.sciencedirect.com/science/article/abs/pii/S0367326X13002578?via%3Dihub after intragastrically administering essential oils for 28 days, researchers found differences in the brains of rats for enzyme activities “(. It was found out that RE showed an inhibition of AChE activity in the frontal cortex by 55% (p b 0.01) and in the hippocampus by 72% (p b 0.01) after 28 days of treatment when compared with control rats (MC + H2O) (Table 2)) and mRNA levels (“A one-way ANOVA analysis revealed significant differences in gene expression of mRNA AChE both in the cortex and the hippocampus”)
[40] https://www.sciencedirect.com/science/article/abs/pii/S0308814607011685?via%3Dihub . Rosmarinic acid was also tested for its AChE and BChE inhibitory effect and found to cause 85.8% of inhibition against
AChE at only 1.0 mg/mL. [enzymes which make the neurotransmitter acetylcholine- MH]
[42]https://www.tandfonline.com/doi/abs/10.1080/00207450390161903 A clear dissociation of the aroma effects on these two memory systems is apparent here, with rosemary enhancing secondary memory and lavender having no effect. [secondary memory = long term memory]
[44]Mark’s study in children in the Rosemary aroma condition (mean = 4.60 words) scored significantly higher than those in the no aroma control condition (mean = 3.37 words),
http://nrl.northumbria.ac.uk/32447/1/ACES_2017102714303062.pdf
[45] [These next 3 citations are for other rosemary studies on memory, also with small or inconsistent finding]: https://www.liebertpub.com/doi/10.1089/jmf.2011.0005 study on the elderly. “This study clearly demonstrates significant dose-specific effects of rosemary on ‘‘speed of memory’’ compared with placebo: positive for the lowest dose (750 mg) but negative at the highest dose tested (6,000 mg).”
[46] https://www.sciencedirect.com/science/article/abs/pii/S1744388117304723?via%3Dihub A randomized
clinical trial… “The results of the current study revealed that rosemary had significant effects on enhancing memory performance, reducing anxiety and depression, and improving sleep quality in university students.” [BUT they used a questionnaire to assess memory, asking things like how often they forgot something, rather than a direct test of memory- MH]
[47] https://www.sciencedirect.com/science/article/pii/S2090506816301944 In ‘‘Lavender” group the median value of correctly reproducible images was 9, and in ‘‘Rosemary” group it was 9.5.The median was 7 in the control group.
[48] There is a paucity of clinical research investigating the effects of essential oils and their use in aromatherapy.
[49] https://www.sciencedirect.com/science/article/abs/pii/S0944711312000529?via%3Dihub Is lavender an anxiolytic drug? A systematic review of randomised clinical trials
[50] Small study found lavendar reduced anxiety https://www.ncbi.nlm.nih.gov/pubmed/11806592
[51] This is the first study to investigate the use of inhalation aromatherapy among children and
adolescents and their parents during SCT. As administered in this study, inhalation aromatherapy
with bergamot essential oil did not reduce transitory anxiety
[52] Study of more than 300 patients: We conclude that, as administered in this study, aromatherapy does not reduce anxiety or depression levels in patients undergoing radiotherapy.
[53] We found that patients who were exposed to orange odor or lavender odor had a lower level of state anxiety, a more positive mood, and a higher level of calmness compared to the patients in the control condition. [No placebo]
[54] Study of more than 300 patients: We conclude that, as administered in this study, aromatherapy does not reduce anxiety or depression levels in patients undergoing radiotherapy.
[55] http://eprints.hta.lbg.ac.at/765/1/DSD_16.pdf The results of these studies are inconsistent, but one ought to take into the consideration the fact that they all report on different types of pain. Also,
the sample sizes in all three RCTs were small, between 30 and 70. Further RCTs are required to establish the pain reducing effect of aromatherapy. The strength of the evidence is low.
[56] https://www.hindawi.com/journals/prt/2016/8158693/ This review is more in favor of using aromatherapy for pain “The findings of this study indicate that aromatherapy can successfully treat pain when combined with conventional treatments.”, but they found possible evidence of publication bias and some studies included aromatherapy with massage (Ou et al., 2012)
[57] Review paper of 15 studies - Ten studies used lavender. Called the results “ promising” Although results were mixed, most studies found a positive association between inhalation of essential oils and sleep. Statistically significant results for improved sleep quality were reported for lavender oil,37,38,41,43 peppermint oil,42 and jasmine oil.45 Problems: Studies are crap quality: all of the study samples appeared to be convenience samples, and only five studies reported recruitment methods. Some studies are tiny. [37] had 15 people in it!. The effect is short term - only lasted 1 week in this study - “We also showed that 24 sessions of aromatherapy improve sleep quality in women with insomnia up to 1 week after the end of the intervention.” European insomnia guideline found aromatherapy is “not recommended for the treatment of insomnia because of poor evidence (weak recommendation, very low-quality evidence).
[58] https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD003150.pub2/abstract The benefits of aromatherapy for people with dementia are equivocal from the seven trials included in this review.
[59] In this study, rubbing essential oils in patients led to an “increase in the resistance to nursing care procedures for some aged care facility residents with dementia. This may be due to the fact that with the essential oils, they are more alert and aware of the possible indignity of being washed and are therefore more resistive”. And otherwise, no difference between oil and no oil.
[60] Compared to the application of placebo, a 10% peppermint oil in ethanol solution significantly reduced the clinical headache intensity already after 15 minutes (p < 0.01) https://europepmc.org/abstract/med/8805113. But, hasn’t been replicated: Recent cochrane review says: There were insufficient data to compare aspirin with any active comparator (paracetamol alone, paracetamol plus codeine, peppermint oil, or metamizole) at any of the doses tested." https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD011888.pub2/abstract
[61] https://www.maturitas.org/article/S0378-5122(12)00006-0/fulltext Due to a number of caveats, the evidence is not sufficiently convincing that aromatherapy is an effective therapy for any condition
[62]https://www.researchgate.net/profile/Larysa_Martynyuk/publication/261747324_Effect_of_the_Herbal_Combination_Canephron_N_on_Diabetic_Nephropathy_in_Patients_with_Diabetes_Mellitus_Results_of_a_Comparative_Cohort_Study/links/56c1d7c008ae2f498efcd2eb.pdf In addition, all of the study samples appeared to be convenience samples, and only five studies reported recruitment methods
[63] https://www.hindawi.com/journals/ecam/2017/5869315/abs/ Seven [out of 12] studies showed improvement in depressive symptoms. Limitations. The quality of half of the studies included is low, and the administration protocols among the studies varied considerably. [for sample sizes, see table 2. Ranges from 13-320]
[64]Study of 24 patients, a capsule containing 90 mg of peppermint oil alone was also able to reduce significantly the frequency and duration of duodenal contractions and the duration of contractions
in the gastric corpus, producing smooth-muscle relaxation in the stomach and duodenum (Micklefield et al., 2003).
[65] https://www.bmj.com/content/337/bmj.a2313 Four studies compared peppermint oil with placebo in
392 patients... Fibre, antispasmodics, and peppermint oil were all more effective than placebo in the treatment of irritable bowel syndrome
[66] http://cochranelibrary-wiley.com/doi/10.1002/14651858.CD003460.pub3/full There is evidence that antispasmodics are effective for the treatment of IBS. The individual subgroups which are effective include: cimetropium/dicyclomine, peppermint oil, pinaverium and trimebutine.
[67] In their meta-analysis of eight randomized controlled trials using peppermint oil as a treatment for IBS symptoms, Pittler and Ernst (1998) found a significant positive effect compared with placebo in five of the studies.
[68] https://www.grandviewresearch.com/industry-analysis/essential-oils-market The global essential oils market size was valued at USD 6.63 billion in 2016, growing at a CAGR of 9.7% during the forecast period.
[69] the authors found 123 (77%) of all patients in the evaluation reported deriving at least
one benefit from the aromastick. The majority of aromasticks were given to patients for anxiety (31%), nausea (28%) and difficulty sleeping (19%). … Patient with lung cancer “She chose a blend of lavender and eucalyptus which she found “hugely successful” both for alleviating her nausea and for encouraging deep breathing and increasing relaxation”
[71] https://www.amazon.com/Scent-Desire-Discovering-Enigmatic-Sense/dp/0060825383/ref=sr_1_1?s=books&ie=UTF8&qid=1532448817&sr=1-1&keywords=the+scent+of+desire
[75] Study in > 150 people Both Essential Oils and the placebo pill evoked positive expectations regarding cognitive performance and alertness. Expectations predicted perceived changes in alertness and heart rate, but not in cognitive performance https://onlinelibrary.wiley.com/doi/abs/10.1002/ffj.3392
[76] a study of 49 kids with cancer found ginger essential oils no better than placebo: https://journals.sagepub.com/doi/10.1177/1043454218782133
[77] When Rosemary and memory compared to placebo: totally inconsistent results: https://www.liebertpub.com/doi/abs/10.1089/jmf.2011.0005
[78] Again, no difference between rosemary and placebo: https://www.liebertpub.com/doi/pdf/10.1089/jmf.2012.0216
[79] https://www.tandfonline.com/doi/abs/10.1080/00207450802333953 To explain these effects, pharmacological and psychological mechanisms were explored and a psychological interpretation of the data was found to be more comprehensive.
[80] http://ecp.acponline.org/julaug00/aromatherapy.pdf Aromatherapy involving essential oils is no more effective than having patients sniff other pleasant odors in reducing preprocedure anxiety.
[81] Editorial on prev cite: Patients awaiting surgical abortion were randomly selected to sniff a blend of essential oils believed to reduce anxiety or to sniff a pleasant-smelling hair conditioner.
http://ecp.acponline.org/julaug00/aromatherapy_editorial.pdf
[82] Study of 300 cancer patients: and the placebo worked BETTER than essential oils : https://www.ncbi.nlm.nih.gov/pubmed/12805340
[83] a study of just under 40 kids undergoing stem cell therapy: found essential oils vs non-essential oil based scented shampoo.. and placebo worked BETTER (essential oil did NOTHING) see Figure 2 https://onlinelibrary.wiley.com/doi/10.1002/pon.1898