Science Vs - Essential Oils: Science or Snake Oil?

Episode Date: September 20, 2018

Essential Oils - and their claims - are huge right now. But is it all hype, or is there something special about these little brown bottles? To get to the bottom of it, we dig through the studies and speak to cognitive neuroscientist Dr. Rachel Herz and psychologist Prof. Mark Moss. Check out the full transcript here: http://bit.ly/2PyEsKy Selected references: Rachel Herz’s books: Why You Eat What You Eat & The Scent of DesireA review of the benefits of peppermint tea and oil A critical review of the clinical trials Mark’s two studies showing that rosemary can enhance memoryThe experiment where lavender had different effects depending on what the people expected it to do  Credits: This episode was produced by Meryl Horn, with help from 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. Learn more about your ad choices. Visit podcastchoices.com/adchoices

Hi, I'm Wendy Zuckerman and you're listening to Science Versus from Gimlet Media. This is the show that pits facts against fragrances. On today's show, essential oils. This is our most requested show yet. You guys really want to know if there is good science behind essential oils. So on today's show, we're going to find out if they make any sense. Sense? Get it? Essential oils are really having a moment right now.

This industry is worth billions of dollars. In fact, as we're recording this episode, doTERRA, which is the big kahuna in this space, is throwing its annual convention, which 30,000 people are attending. So, yeah, this is huge. So, we sent our senior producer, Caitlin Sori, to sniff out the essential oil scene. Really diffuse the situation. Hi, Wendy. Hi, Caitlin.

Yeah, I went on an essential oil adventure, probably the nicest smelling trip I've been on as a reporter. Ooh. So I went to this store in Manhattan and they have these essential oil 101 nights where they teach new people about essential oils and I was like, this could be a really good place to start. Right now I'm smelling the Manhattan musk. It's nice.

Oh, it is nice. So everyone's sitting on stools, paying attention, being good students, and they're following this class that's been led by Joe. What is aromatherapy? It's the art and practice and the science of using essential oils. Joe's a David Bowie fan. He was wearing this awesome David Bowie T-shirt, and he's got this hair that goes down past his shoulders.

And he's been working at that shop for 17 years, and he was surrounded by so many oils in the shop, I just couldn't imagine what his house was like. It's a mess. In the bathroom, I've got oils. In my bedroom, I've got oils. In the living room, there's oils there. And then in the closet, there's a whole big boxes of all oils. So Joe's got a lot of essential oils in his life. And he sees them as kind of a medicine cabinet

where each oil can do a different thing. Right. So is this like the key to essential oils? It's not just nice smells. There's something special in each oil. Yeah, so each oil is coming from a different plant, right? So they've got different chemicals in them. So Joe gave me a bit of a list of like some of his favorite oils and what they can do. If you put peppermint on your skin, it's actually a mild anesthetic. So it's great for pain. Peppermint is also great for digestive issues. Rosemary, as far as stimulating your neurons, your brain cells, something you don't want to mess around with before going to sleep. Whereas lavender would be much better at that time, or chamomile. So a lot of the class was like this, talking about what essential oils can work for,

from skin conditions to improving your mood. So this is exactly the kind of thing that I start to get sceptical about. Surprise, Wendy's sceptical. Well, I mean, it's just like, how can these oils do all these things? Like, it's some kind of panacea that like, oh, this one's for stomach aches, this one's for headaches. Oh, your toenail hurts? You can have some of these. You know, it just sounds like classic snake oil.

Sure. I hear that. There's lots of promises. But Joe said this one thing to me that I was like, huh, maybe there is something here. So he was talking about that medicine has its roots in plants. Its roots in plants. Yeah. Very nice.

I'll leave that where I found it. Yeah. Like aspirin came from willow bark originally, and there's a treatment for malaria that also comes from a plant. So in his mind, essential oils are kind of part of that universe. There's a lot of science. They aren't just empty scents. They contain medicinal value.

Okay. So you spent a night hanging with Joe and a bunch of other people learning about essential oils. Where do you stand at the moment? Like, do you think there is a unique quality in essential oils? You know what? I wouldn't rule it out. I wouldn't rule it out because until we've done the digging,

like, it makes sense. Like, these are different kinds of chemicals. Why wouldn't they have different effects? Maybe there's something to this. I'm open to it. All right. So as a woman of science, you should be open to it too. See where the evidence takes you.

Whoa. Whoa. You are absolutely right. I have done no digging, only judgment. Time to do some digging. OK. So after that chat with Katie, we really started going down the rabbit hole on this.

And it turns out that there is a lot of research into essential oils and scientists have been studying them for decades. They've been looking at all kinds of stuff, like whether these oils can ease anxiety or improve memory. Some scientists are even looking into whether essential oils can cure cancer. So, what have they found? Could essential oils really be nature's amazing medicine cabinet? When it comes to essential oils, there's lots of lovely smells.

But then there's science. Science vs. Essential Oils is coming up just after the break. Bumble knows it's hard to start conversations. Hey. No, too basic. Hi there. Still no. What about hello, handsome? Who knew you could give yourself the ick?

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Think of it as your guide for all things AI, with the most human issues at the center. Join me every Wednesday for Pioneers of AI. And don't forget to subscribe wherever you tune in. Welcome back. On today's show, we're looking at essential oils and whether they really work. Because there are tonnes of claims bouncing around online about all these health problems that essential oils can treat. One of the most extreme claims, though,

is that essential oils can fight cancer. You can find legit-looking websites arguing that these oils can treat cancer, and even testimonials where people say basically that essential oils cured their cancers. And these claims mean that lots of people end up coming to essential oil shops, like the one Joe works at, searching for answers. And it's very sad because they're looking for, desperately looking for help for themselves or for a loved one. So you have people come in regularly being like,

I've heard that this might help? Calling, emailing, coming in, yes. And these people point to the same kinds of studies to support their claims. Studies showing essential oils stopping cancer from growing. Now, these studies are real and a lot of them are published in peer-reviewed journals. But if you're smelling a rat, it's probably because all these studies have been done in rodents or petri dishes. Point is, they're not in humans. And we've shrunk tumours in mice so many times,

with so many different chemicals, and they barely ever work in humans. Now, in the trials that have tested if essential oils can shrink people's tumours, it doesn't work. And it can even give cancer patients nausea. Even Joe, who thinks essential oils can work for all kinds of things, knows that they don't cure cancer. There's not proof that this is shrinking tumors. That's unconscionable hype. That's hurting a lot of desperate people that we deal with here just about every day. Okay, so that's one of the extreme desperate people that we deal with here just about every day. OK, so that's one of the extreme claims out there about essential oils. And it's basically rubbish.

But what about this idea that essential oils can help you feel more relaxed or improve your memory? Well, here's where the science gets a lot more interesting. Hello. Mark. Hello, Mark. Yes, hi. Hey, lovely to meet you. How are you? Oh, hello, kitty cat.

We sent a British producer to meet Dr Mark Moss and his cats, all four of them. As soon as I get home, as soon as I open the door, he's like, wow. Mark is the head of psychology at Northumbria University in the UK, and he studies how we can improve our brains and our memories. And Mark got interested in essential oils after a grad student had an idea. She wondered, could a particular oil make our brains work better? She came to me and said, do you know, what do you know about rosemary?

I said, well, it goes well with potatoes and lamb, but I don't really know anything else about it. And she said, well, rosemary is supposed to be good for improving your memory. So he starts looking into it and he realises that this has a long history. Ancient Greek scholars used to wear garlands of rosemary around their heads when they were preparing for exams. Shakespeare wrote about it in Hamlet, where Ophelia says there's rosemary, that's for remembrance. And Mark thought, well, if it's good enough for Billy Shakespeare, it's good enough for me.

No, of course not. But it did get him thinking. Is this possible? Like, how could a smell have an effect on your brain? And here's one way Mark thinks that it could work. When you inhale chemicals, they go into your nose, into your lungs, and from there, they can go into your bloodstream and then up into your noggin. But if you're a chemical, getting into the brain is actually pretty tough.

Now, the brain is rather more restrictive in its access than the lungs. It's a bit... A bit of a VIP situation. Yeah, yeah, it is. It's got quite a heavy sort of dormant system, the brain. That heavy dormant is a barrier between the brain and the rest of the body. It's called the blood-brain barrier, and it's there to protect our brain from bacteria and other nasty stuff.

But some chemicals do squeeze past the Dorman, which made Mark think that the idea behind essential oils isn't crazy. And so he wanted to test it out to see if it would work with rosemary and if it could actually improve memory. So Mark and his team set up this experiment. They got almost 150 people to come into his lab and then made them do this memory test on a computer, while some got the smell of rosemary wafted into the room. Now, Mark didn't want them to know that the smell was part of the experiment because he didn't want it to influence the results. So he figured out a way around it.

By, well, lying. If the participant says, oh, there's a smell in here, it smells like, oh, I don't know what that's all about, somebody was in here earlier, it's 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 to see if the rosemary group did better. And so what did you find? We found that rosemary improved people's long-term memory. Yeah, rosemary helped people in the study remember more, 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. And Mark has done a similar experiment in school kids where he found the same thing.

It's demonstrating that there is something going on when you're exposed to rosemary aroma. But before you shove your nose in some roasted potatoes, here's something you should know. Mark's results are very subtle. Like, very subtle. The people who got the rosemary only remembered a tiny bit more than the other group. When you averaged it out, it wasn't even a full word more. And Mark totally acknowledges this. The amount of evidence that we've got at the moment,

you know, it's not enough to go jumping off a cliff about. The effects are typically quite small. Yeah, absolutely. Essential oils are not magic bullets. They aren't the sorts of things that you say, oh, I'm having difficulty sleeping, get the lavender out, that's me out for the count. Or waking up one morning and thinking, oh, I'm having problems with my memory, I'll get some rosemary out,

that's me, I can remember the complete works of Shakespeare now. 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 that essential oils can't help some people. These are mild effects, but I would argue they are still real effects. Just because they are small doesn't mean that they don't potentially have inherent value for us. Do you use essential oils? No.

What? No, it's my job. I do research because it's my job. But don research because it's my job, you know. But don't you want, you know, a better memory or to sleep better? Well, yeah, I'd also like a six-pack, but I don't go to the gym, you know. It's like... 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. 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 are lots of claims out there about the powers of essential oils, that lavender can help with sleep and anxiety,

that peppermint can stimulate you and even reduce your headaches. So we scoured through the research, searching for evidence that essential oils could help with all kinds of things, anxiety, depression, pain, sleep, headaches, dementia, even killing bacteria. And what did we find? Well, there was no consistent evidence that essential oils could help us with any of this stuff. Either the quality of the studies wasn't very good, or some studies would find an effect and then others wouldn't,

or there was promising evidence that it was in petri dishes or with animals. Still, though, there was one thing that stuck out, where essential oils had a solid effect that was backed up by good research in humans. And it was this. Peppermint oil seems to be helpful for upset stomachs, but not by wafting it under someone's nose, by eating it in concentrated capsules. Which is all to say that the clinical trials for the vast majority of essential oils are very, very underwhelming. And yet, there are thousands of people who swear by essential oils. People with no financial stake in this game saying, yeah, they really work. So what is going on here?

How can people feel better on essential oils, but it's not showing up in the clinical trials? Well, to walk us through it, we're interviewing Zoe, the talking dog. You're going to be on the internet. Zoe, come. No, no. We're interviewing Zoe's human, Rachel Herz. Off the couch. Off the couch. Come on. Good girl. Okay. So anyway. Rachel is a cognitive neuroscientist at Brown University who researches smell. And she's written a book about the power of smell called The Scent of Desire. Now, Rachel believes that essential oils can work, but not because they're having a specific effect on our brain. It's because of something very

different. And to explain it to us, she told us this story about when she was little. Rachel was five years old. It was a summer day and she was in the backseat of her parents' car. And all of a sudden there was a scent. And my mother said, oh, I love that smell. And I'm in the backseat and I love mommy. And mommy says she loves that smell and it's a beautiful day. So I thought, well, this is a great smell. Rachel still remembers this beautiful smell. So for me, I would describe it as a cross between garlic and chocolate. And then it wasn't until a couple of years later, I said, oh, I love that smell. And my friends on the playground went, ew, that's gross, that's disgusting, you're so weird.

Why were they so mean? Well, because Rachel was smelling a skunk. And she says the reason that she likes the smell of skunks is because her mum, who she loves, told her that it was a nice smell. And so she associated it with this lovely memory of driving through the countryside on a summer day. And to take this back to essential oils, Rachel says something similar 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 you smell this, you're going to feel this way.

And then they do. So you walk into an aromatherapy shop and the purveyor has all their essential oils out for you. And they're going to tell you that this one is very relaxing and or meditative or this one's going to help you focus, this one's going to help you de-stress, this one's going to be revitalizing. And the fact that they're telling you that is 98% of the effect. So is this just the placebo effect? Basically, yes, it is just a placebo effect. Now, the fact that essential oils could be completely placebo doesn't mean that people don't feel effects. Being told that something can have an impact on your body can actually cause an impact on your body. In fact, placebos

are so powerful that lots of experiments must control for them. Exactly. And that feeling is real. I am not disputing that one bit. The feeling is completely real. Still, though, how can Rachel be so sure that what's happening with essential oils is the placebo effect at work? Well, for one, Rachel is not convinced that the amount of chemicals that get into your body when you smell essential oils could have a strong effect on your brain. She also gets her evidence from this rather curious experiment that was done in 90 people where some were given something to smell. And the researchers set it up by saying... There's a scent that's going to be presented that either people think is really stimulating and energising or relaxing and calming. And all through the experiment, the researcher measured their heart rate.

And here's what she found. When people were told this scent was going to be stimulating, their heart rate went up. And it even made them sweat a little. When others were told the smell was going to be relaxing, well, their heart rate tended to go down. And guess what? Both groups were given the same oil, lavender.

So it had nothing to do with the lavender. It was just to do with what people were told. And this is why we think lavender is relaxing. We have learned it to be relaxing, but it could just as easily be marketed as being stimulating. When you read that study, what were you thinking? Great. Why great?

This vindicates because everything that I believe about smell is through learning. And so there isn't something magical and inherent to the scent, whatever it is, that's going to make you feel one way or the other. This is all about learning and not to do with some like drug-like effect. This is just one study, but we found scores of others suggesting that essential oils don't do anything above a placebo. So when it comes to essential oils, do they pass the sniff test? Well, there are all these claims that essential oils have 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. Hey, Wendy. Hi, Caitlin. Sorry. I've got something to tell you. What? I have a little secret. I'm going to out myself to the science versus community. What? What is this? I use essential oils.

What? I have a whole bunch of them at home, like a whole stash. Like I'm talking peppermint, orange, lavender, eucalyptus, tea tree oil. What? Yes. Why? Why? Because they're nice.

But you know there's no special chemical in them, right? So what? What do you use them for? I put them in my bath. I put them in a little diffuser next to my bed when I go to sleep. It's nice. I feel good. But it's annoying that these companies are parading around like there's concrete science here. Like, they're not just saying, like, it's nice, put a diffuser on.

They're using science. They're coming into our turf and saying we have a scientific basis for all of these claims. And their science is for the most part rubbish and that is annoying. Some of them even go around wearing lab coats. Wendy, you seem very agitated. I think I know what you need. I think you need some lavender in your bath.

Stop it. Try it. Might work for you. Stop it. That's science versus essential oils. And for this episode, there are 103 citations. So if you want more information, check out the show notes. There's a link to the script and all the research you can handle. This episode was produced by Meryl Horne, with help from me, Wendy Zuckerman, Rose Rimler and Odelia Rubin.

Our senior producer is Caitlin Sorey. We're edited by Blythe Terrell and Caitlin Kenny. Fact-checking by Michelle Harris and Rose Rimler and Odelia Rubin. Our senior producer is Caitlin Sorey. We're edited by Blythe Terrell and Caitlin Kenny. Fact-checking by Michelle Harris and Rose Rimler. Mix and sound design by Emma Munger. Music written 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 Elizabetsky, Belinda Hornby, Diane McKay and Thomas Cleland. And an extra thanks to the Zuckerman family and Joseph Lavelle Wilson. Next week, we're tackling veganism. Do you need to eat meat and dairy to be healthy? I f***ing hate vegans. They expect my bones to turn to dust or something bad to happen,

but no, I'm still walking around. I'm Wendy Zuckerman. Back to you next time. Whatever, Wendy. You just don't get it. You don't know what you're missing out on.