Bland, dry and depressing. How our sense of taste remains under researched and pivotal to wellbeing...
25 January 2022
Presented by Julia Ravey, Harrison Lewis
Production by Harrison Lewis.


Cooking school


Taste is wonderful! Think of all those occasions where you and loved ones or firends are brought together by food! You may not realise, but our sense of smell, our 'fifth sense', is intertwined with taste; they are essential to our happiness and wellbeing. We’re taking a deep dive into how your smell and taste work. We’ll be hearing from someone who suffers from a condition called phantosmia, how we can normalise smell training and maybe we’ll get a spoonful of scientific cooking work-arounds designed to help those suffering from smell and taste disorders. Also, in the news this week: an update on what the future seems set to look like whilst we 'live' with COVID-19, the benefits of playing action video games and how the brain filters familiar and unfamilar sounds whilst you sleep tucked up all cosy in bed...

In this episode

Coronavirus exit

01:03 - Covid restrictions back to 'Plan A'

Why has the government decided to slowly end 'Plan B' COVID restrictions?

Covid restrictions back to 'Plan A'
Linda Bauld, University of Edinburgh

This week the UK government announced the end of the enhanced “Plan B” covid restrictions that were introduced last year in response to the arrival of the omicron variant. Some have been sceptical about the timing, particularly given that we’re still detecting around 100,000 cases per day. Chris Smith asked Edinburgh University public health specialist Linda Bauld to take him through why, in her view, the government have made the decision they have…

Linda - The UK government was very clear. They didn't want to keep "Plan B" in place for any longer than necessary, and that's an important principle that they are sticking to. What they've been looking at is a basket of indicators. The first one is what's happening with infection in the community, and they look at population surveys and private households, and also cases. You can see cases have gone down about a third over the last seven days. They're then looking at capacity in the NHS, but admissions to hospital have not gone anywhere near what was feared in some of the modelling. In fact, over the last seven days, they've gone down around 5%. Importantly they're also looking at intensive care and that has not been stretched primarily because of vaccines. What they are concluding is that the Omicron wave has been a big wave, but it's mostly been of infection and not severe outcomes. Therefore, they can't keep restrictions on the population longer than they think is necessary.

Chris - One point that some people have indeed made at one of the Downing Street press briefings is when one of the journalists said, 'But look, we've still got very high levels of mortality.' What's the reason that they're comfortable having that number of mortalities, but still making these changes?

Linda - I think there's a recognition that the vaccines are not 100% protective. People might be older and more vulnerable and, like with other viruses, we may always have people who lose their lives as a result. They've never been willing to state a threshold for tolerating that but I think, at this stage in the pandemic, they're recognising that there will be some ongoing harms and also that they have to balance those up against the other accumulated harms to the economy, education, social harms, etc.

Chris - Because, Susan Hopkins, from the UK Health Security Agency, she was also presenting this week and she alluded to, as I think did Sajid Javid, a survey that the office for national statistics are carrying out which is looking more closely at death statistics and death certificates to try to understand what really constitutes a death from COVID as opposed to a death with COVID. Someone might have died of something else, for example, but they happen to have also tested positive for COVID in the last month?

Linda - That's right. When you look at the death certificates, the analysis does suggest that, at the moment, the majority of those people who are losing their lives are losing them because of the COVID infection. But, there is also a substantial group for whom it's just one factor. The other thing we've done some analysis on in England is looking at the proportion of people in hospital because of COVID or with COVID. You can see there's now a greater proportion than earlier in the pandemic who are there with COVID. In other words, they test positive when they come into the hospital rather than they're there because of COVID.

Chris - I think the number that was cited was somewhere between 40% and 50%. So, it's quite big, isn't it? People who were in hospital, but happened to be detected to have coronavirus infection, but they're not there because of it.

Linda - That's correct. I'm most familiar with the data from Scotland and, in Scotland, 60% of people who are in hospital with COVID are there because they are being admitted for COVID, but 40% or 4 out of 10 people, which is a big number, just happen to have COVID but are perhaps being admitted because they've had a fall or they're in for a treatment, etc.

Chris - One of the things you raised just now was you said, 'intensive care beds'. That is probably the most reassuring graph that's being presented, isn't it? In the sense that the number of people who are in ventilation facilities is now lower than it was before Omicron arrived on our shores. I suppose that's giving policy makers quite a lot of confidence that actually we are not seeing a translation to severe disease like we did. Therefore they probably do feel more comfortable easing restrictions despite the fact we still do have high numbers of cases: 100,000 a day.

Linda - That's right. There's two really interesting features about intensive care: one of them is that the admissions are as low as they were last summer when so-called 'Freedom Day' was introduced in England. You can see from a policy perspective, if you're focusing on that indicator, there's not a rationale to retain restrictions from the government's point of view.

Chris - I'm very much a glass half full person, and I'm quite optimistic about the direction of travel, but let's assume that these measures; stepping back from them is the right thing to do, and we do end up back in a position where we were last summer. What should the focus shift onto? What do you think we should really dwell on next to make sure that we are as prepared as possible for next winter, but also the twists in the road that may still be yet to come?

Linda - I share your optimism for the next few weeks and months, but I think there's a number of factors. The first one is, let's keep a close eye on waning protection from vaccines. The 'Joint Committee on Vaccination and Immunisation' said no booster at the moment. That seems definitely proportionate. There are indications from Israel that their rapid rollout of a 4th dose may not have had an impact and may not have been necessary. The second thing is looking ahead, we have to give people good and accurate advice about their own behaviours so that they can protect themselves. An assessment of risk for an individual will vary depending on how much of a risk COVID is to you. That might be face coverings, even if they're not mandated, distancing, thinking about avoiding crowd places, etc. The third thing is, think about environments; how do we COVID proof/improve different environments? How do we use ventilation? How we think about working environments like offices? What can we do in schools where there is still arguably more we could do? Etc. The final thing is surveillance. The big threat for the future is a new variant, and we need to just make sure we're participating with all our global collaborators.

Kid playing video games

06:22 - Level-up learning through action video games

Action video games may help you shoot for higher academic grades than expected

Level-up learning through action video games
Angela Pasqualotto, University of Geneva

Action video games get a bad rep, especially when it comes to how age-appropriate certain video game genres are for young children. But new research from the University of Geneva suggests that there could be some unexpected benefits to playing video games. Tricia Smith interviews Angela Pasqualotto…  

Tricia - I like to play video games to decompress after a long & exhausting... er, I mean a wonderful and fulfilling day at the office. But did you know that playing video games could be good for children's literacy? I'm not talking about educational games either: it's action games - Call of Duty, Halo, Overwatch, even Fortnite. It's games where you have to focus on lots of things happening at once and make decisions quickly that could make a difference. Sounds too good to be true, right? But Angela Pasqualotto explained:

Angela - We know that reading is, at its core, a linguistic skill, yet it relies not only on oral language abilities, but also on several executive functions like working memory, cognitive flexibility and inhibitor control. In particular, reading calls for an official extraction of the visual information from the page. It puts special demands on eye movements and attentional systems. That's why attention and control is involved and is crucial in reading.

Tricia - And when you were testing the effect of action video games compared with a non-action video game, what were the main findings of that study?

Angela - Training all these attention control and executive processes promoted not only attention and control per se, but also reading skills in Italian speaking children that were between 9 to 12 years old. What is interesting to notice is that these improvements were maintained 6 months later after the end of the training, and also influenced school grades in Italian at 18 months after the end of the training.

Tricia - So, just by playing an action video game compared to playing a game that was not action, you're getting these improvements in reading skill.

Angela - Exactly.

Tricia - Is that gonna be the same for other languages?

Angela - This is part of what we are doing right now. The game will be adapted into German, French, and English, and deployed in these four languages. The main aim is that we would like to understand how to alleviate the different roadblocks to literacy acquisition, because all these languages are very different in terms of autographic characteristics. The link between the sound of the language and the way in which it is written is very different between all these four languages. We expect our game to be beneficial where the extent of whether these different in terms of transparency or in the writing systems is still an open question.

Tricia - These benefits that you get in improving your executive functions by playing these action video games. Is that a benefit that I - at the age of 28 - will be seeing? Or is that something that you think happens just during the initial learning process?

Angela - Luckily for us, it is something that we can expect. It happens throughout our entire life. It is due to our incredible ability of the brain to modify and reshape due to intensive training. We could expect that children who have higher brain plasticity can benefit more from this kind of training. But this doesn't mean that it doesn't make sense even as adults to train our brain functions.

Tricia - What do you think about the negative stigma that's associated with kids playing video games all the time?

Angela - I'm a completely non-gamer despite the fact that I'm developing video games. I completely get that there is a stigma surrounding this topic and, as always, there is no clear specific answer that we can give. But what we can say is that the right amount of these kinds of action video games is certainly producing a positive effect on conditions. It is worth considering that there are positive impacts in playing video games.

Mother & infant child in field

11:20 - Infants spot sharing saliva in relationships

Infants can recognise relationships by looking for if the people involved share saliva with each other...

Infants spot sharing saliva in relationships
Ashley Thomas, MIT

Children as young as 8 to 10 months old can distinguish when two people have a special - or “thick” as it’s known - relationship between them; such as being a married couple, or a parent and child. This is in comparison with close, but less special relationships, for instance between two friends. You could say this is just learned behaviour, but actually it looks like they’re using a very specific clue to work out which relationships are the important ones: if they see two other individuals sharing saliva - including by sharing food - that’s the giveaway. And when that happens, they judge those relationships to be special. Chris Smith interviews Ashley Thomas from MIT, who used puppets to test this out on human infants…

Ashley - Some friendly relationships - you can think of everyone you'd be willing to share an ice cream cone with - those are people who you feel close to, but you have other friendly relationships that you don't necessarily feel so close to, but you're still very friendly with. So that's the distinction we were after. And what we wanted to know is whether infants who have very little experience in the world distinguish between those two types of relationships.

Chris - Would this be sort of like the relationship that a parent would have with a child versus the parent's friends would have with that child?

Ashley - Yes. So that could be one place where there's a distinction, or you could think of your coworkers versus your family.

Chris - How did you set out to test this?

Ashley - We showed infants and toddlers people interacting with puppets. And in one of those interactions, we showed them saliva sharing. In another one of those interactions, we showed them something that was prosocial or cooperative, but didn't involve saliva sharing. And then we asked, given those two different interactions, who do the infants and toddlers expect to respond to the Puppet's distress or to comfort the puppet when it's upset.

Chris - When you say saliva sharing, do you mean literally?

Ashley - Yes, I do mean literally. But in this case we used food sharing. So, again, you can think of sharing an ice cream cone with someone - you sort of accidentally share saliva - but you might not be willing to do that with everybody that you know, just people who you feel close to.

Chris - What was your hypothesis then? That if saliva sharing matters they'll pay more attention to the individual with whom there had been saliva sharing rather than the one there hadn't?

Ashley - Yes, but only when the person that they had shared saliva with was upset.

Chris - Why was being upset important?

Ashley - Just like saliva sharing happens with these close relationships, so does comforting. You can also think about everyone who you would really like to comfort you when you feel sad - those tend to be people that we feel close with. And there tends to be overlap with the people who you want to comfort you and the people who you're willing to share saliva with, or share an ice cream cone with.

Chris - And is that what happened?

Ashley - That is what happened. So after infants and toddlers saw that two individuals shared saliva, they expected those two individuals to respond to one another's distress.

Chris - How does one disentangle learned experience from what's innate here?

Ashley - We can't. We tested 8 to 10 month olds who are really young and don't have that much experience in the world. But, we don't know what's innate and what's learned, but we do know that if anything's learned, then it had to have been learned really rapidly and quickly.

Chris - And does this cross cultures?

Ashley - The idea that people who are close share saliva does happen in many, many different cultures across the globe, but we don't know if infants would make the same inferences in different cultures because we haven't tested that yet.

Chris - And do you think that grownups sharing saliva or other things is part and parcel of the same underlying mechanism of trust, comfort and building relationships?

Ashley - Yeah, definitely. One thing that's cool about humans is that we can create new types of relationships or we can change a relationship that's not so close into a closer relationship. And one way that humans might communicate this is by doing these saliva sharing actions with each other.

Chris - What do you think the implications are of this?

Ashley - I think the implications are that really early on infants and toddlers are paying attention to the people around them. And they're not just paying attention to who's, who. They're paying attention to how people are connected and who's connected, and that might allow them to figure out who else would be good at taking care of them.


Alarm clock by someone sleeping

16:03 - Why unfamiliar voices disrupt sleep

How does your sleepy brain decipher between noises which pose no threat and those that are dangerous?

Why unfamiliar voices disrupt sleep
Mohamed Ameen, University of Salzburg

When you try to sleep for the first time in a new place, you may find it hard to settle. While tossing and turning might leave you feeling knackered the next morning, your brain thinks its constant surveillance is doing you a favour. But how does your brain tell a safe noise from a real bump in the night? Julia Ravey interviews Mohamed Ameen from the University of Salzburg…

Julia - Every night we lay our heads down and slip into a state of semi unconsciousness. Certain noises you are used to don't disturb your slumber. Even familiar voices (Julia, Julia) like Naked Scientist, Harry Lewis, can be ignored. But if you heard an unfamiliar voice (Julia!), your eyes would most likely ping open, and you would be on hyper alert. But how does our brain decide what we should wake up to and what we should ignore? I spoke to Mohamed Ameen from the University of Salzburg who investigated just that...

Mohamed - When you're asleep, you're not completely unconscious. There is at least a very low level of monitoring the environment that is going on, and that was already evident years ago when scientists showed that sleepers respond selectively or preferentially to their own name. This means that we can at least still have a low level of processing that enables us, even during the deepest stages of sleep, to tell the difference between different stimuli.

Julia - There must be a fine balance of the brain wanting to keep us asleep, but also not wanting to miss out on any potentially threatening situations. So, how does it decide what sounds are normal and what could potentially be something that we need to be aware of?

Mohamed - When a certain stimulus is presented, the brain responds in a way that facilitates a very low level of processing that then tells you, 'Okay, this stimulus is normal. This is something I expect in this environment', or 'this is something that I don't expect'. And then, for a very, very short time, the brain goes into more wake-like activity and then decides whether to disrupt, sleep or continue. And this is like, 'okay, it's fine'

Julia - What stimuli did you use in the study?

Mohamed - We used the subjects first names and other different names. But the difference is that these names were spoken by either a familiar voice or an unfamiliar voice. A familiar voice is a voice that you're used to you - your parents, your partner - and an unfamiliar voice is a voice of someone you've never heard before. We couldn't find a very strong effect of the name, and we think that this is masked by the much stronger effect of the voice, because this is probably a much simpler stimulus to process. So, at this very level of voices, the brain can already tell the difference, even when you're in deep sleep.

Julia - Is that why, when I stay in a hotel, if someone walks past the door and they speak, I wake up. But if I was at home and someone walked past my door and spoke, because it'll be like my family member, I don't necessarily wake up. Is that potentially why that happens?

Mohamed - It could be, yes. The idea is that you are familiar with the surrounding environment. So, for example, when people first sleep next to a train station in the beginning, you always wake up when the train passes. And then, after time, you realise that this is a familiar stimulus that imposes no danger, and there's no need to disrupt your sleep.

Julia - I used to live on an ambulance route in London and, when I first moved there, I was woken up all through the night because ambulances would be going past all the time. Within a few weeks, I didn't wake up to those sounds at all. With your experiment, did you see anything similar with these unfamiliar voices?

Mohamed - We saw something that is within the night. We realised that the brain can even learn something about the stimuli that are presented. When the brain realised that this is an unfamiliar voice, it elicits certain brainwaves and, these brainwaves, we saw a lot of them in the first half of the night. In the second half of the night, as the stimuli are repeatedly presented, these responses decrease gradually, specifically to the unfamiliar voice. This suggests that the brain is learning, 'okay, this has happened before but imposed no danger' and it learns, it predicts something, it gathers information and compares its prediction to what it actually received or heard.

Julia - Sort of like: 'that sound is nothing to worry about. You don't need to wake up from your eight hours sleep, no point disturbing that really precious sleep that we get.'

Shipping in Antarctica

20:47 - Biofouling in Antarctica

Antarctica's experiencing more shipping traffic than first thought, which could be affecting its biodiversity

Biofouling in Antarctica
Arlie McCarthy, British Antarctic Survey

As the coldest and driest continent, Antarctica has a relatively small amount of biodiversity when compared with the rest of the world. The ecosystems which are found here, however, are now expected to begin feeling the disturbance of the growing number of ships which pass through the surrounding waters. The potential consequences on the local environment are the subject of new research by Dr Arlie McCarthy at the University of Cambridge. Harry Lewis was sent to find out more, and began by asking why we’re starting to see a larger number of ships pass through Antarctica in the first place...

Arlie - There's a process called biofouling, and that is where any part of the ship that is connected to the water gathers growth. This is because, in the seawater, there are all kinds of different lavie and early stages of different seaweeds and animals. And then it can take those to a new part of the world.

Harry - Are there enough of these ships to really make an impact or is it quite a small number?

Arlie - There are about 100 to 200 ships that visit Antarctica every year. Most of the ships that visit Antarctica or the Southern ocean are going there because that's where their destination is, like research vessels that are studying all different kinds of things related to Antarctica, whether that's ice and oceans or whales and penguins, or other animals that live there, or even tourist ships that visit Antarctica. And there are fishing vessels as well. Compared to the almost hundred thousand commercial shipping vessels on the ocean, it's a very small proportion. However, they're still large ships, and they can have quite a lot of organisms. Antarctica is the only place in the world that has no marine invasive species, and so every ship that arrives still has chance to introduce something new to Antarctica that wasn't already there.

Harry - Are there any species that we will be familiar with that spring to mind when we're talking about these invasive creatures?

Arlie - Things like muscles - the same muscles, essentially, as the ones you might eat in a restaurant or buy at the fish and chip shop. They grow really, really well on ships. People might also be familiar with barnacles and there are a few different kinds of barnacles as well.

Harry - And why are we worried about these being dropped off in locations that they wouldn't normally be found?

Arlie - We know from other parts of the world that non-native species can have drastic effects on local ecosystems. This could be that they change the way nutrients are cycled, or they could change the interactions between species - so they could outcompete other species. As for Antarctica, it's difficult to know exactly what effects any new species could have, but we know that things like muscles and some kinds of barnacles have no equivalent in Antarctica, which means that they have the potential to have a big effect.

Harry - Arlie, I feel like the idea of invasiveness and us taking animals that shouldn't belong somewhere from one location to another is quite well recorded. So what is it that you found that differs or that expands this knowledge?

Arlie - We found that the places that are most often visited by ships in Antarctica are also the places that are changing most with climate change, so they're getting warmer. Up until now, we've thought that the temperature and the environmental conditions in Antarctica have really been almost like a protective force field, preventing anything that didn't evolve in Antarctica from surviving there. But if those conditions are changing, then the potential for new species not just to be introduced but to actually survive and to thrive is changing as well.


26:01 - An introduction to losing taste

Taste can be affected by a wide range of disorders, but how essential is it to your everyday way life?

An introduction to losing taste
Barry Smith, University of London, Claire

The festivities of the Christmas period are well and truly over; it almost feels criminal to bring them up again. But, I'm sure you can easily recall the indulgent spreads and generous glasses of bubbly. It's a good thought, isn't it? Well, for a growing subsection of the population, it might not be. Since the start of the coronavirus pandemic, more and more people have been left with a distorted sense of smell and taste. Out of our five senses, these two definitely seem to rank as the least important, and research is fairly limited in comparison to, let's say, eyesight. Two years on from the initial spread of the virus, what do we know about these mysterious disorders? Harry Lewis went to Future Dreams house in King's Cross to have a good nose at our senses with Barry Smith, professor of philosophy at the University of London and co-director of the centre for the study of the senses...

Barry - So I think we need to start with the idea that we all enjoy food and we all enjoy eating, but what happens when eating goes wrong? What happens when you can't get experience and enjoyment out of food. And that can happen for a number of reasons. Now, we all know that COVID has very often left people with no sense of smell, and when they lose their sense of smell, they suddenly realise how big a contribution that was to tasting the flavours in food, because all the tongue will give them is salt, sweet, sour, bitter, savoury, umami. But everything else, pineapple, mango, melon, the difference between chicken and pork, that's all coming from the nose.

Harry - As Barry alluded to, smell and taste can be affected by a diverse range of conditions and circumstances. You might find it surprising to hear that head injuries, dementia and even chemotherapy treatments can result in a lasting alteration to our sense of smell. And it's our nose that does some of the really heavy lifting when it comes to exploring flavour. As Barry explains:

Barry - Now, when we're eating food, we're using our tongue to get taste, we're using our nose to get the smell and aromas of food, and we're also using this other thing, the trigeminal nerve; that's the fifth facial nerve that serves the eyes, the nose and the mouth. It's the one that rings bells when you have too much wasabi and you feel it at the bridge of your nose - Ow. Now, sometimes, when people are undergoing treatment, that's completely muted. We saw that with COVID too, that people said I could eat a whole jar of mustard and no tingle, no response. But what we're now seeing is that people recover from smell loss, have a week or two where they think their sense of smell is restored and normal, and then they're developing this very, very disturbing condition called parosmia, and parosmia is the distortion of familiar smells. So things you liked, like coffee or chocolate, now become disgusting. I mean, really, really disgusting. The best description I've had from a patient of how coffee is with parosmia is that it's like fruity sewage. Nobody's going to have that.

Harry - So, if somebody else is sitting at home right now, and they're listening and they think to themselves, 'I think I'm suffering from this.' What are those flavours that are likely, what are the patterns of those flavours that are likely to be affected? Or those food or drink items?

Barry - We know that it's coffee. We know it's roasted meats, onions, garlic, eggs, even toothpaste, surprisingly enough, minty toothpaste. A lot of people have switched to cinnamon flavoured toothpaste. Cinnamon seems okay. By finding out which foods are really unpleasant, we learn which are the trigger foods and which are the safe foods.

Harry - Someone who has been figuring out those safe foods all by herself is Claire. When I spoke to her, she did tell me that her condition differs slightly from the symptoms described by Barry.

Claire - Yes. So Christmas Eve last year, myself and my partner both tested positive for COVID. It was a little bit frustrating because we had basically been living like hermits for the previous eight weeks. And yeah, it's changed my life really. If you'd have said you know, fast forward a year, I'd have been in this position, I would never have believed you.

Harry - And what is that position? What is it that resulted after COVID?

Claire - I realised that my smell and taste had departed and I'd kind of hung onto the hope of the six to eight weeks that everybody was telling me that it would bounce back. But as I've gone past each milestone, actually it's now two months, three months, four months. And I'm two weeks away from it being a year, or just under two weeks.

Harry - Yeah. And I think a lot of people are in that situation where they lost their sense of smell and their sense of taste and it returned. But for you, something different happened, didn't it?

Claire - So they term it as phantosmia. So I've ended up having a smoke smell that can come on via a headache, and it'll be with me 24/7 for a week, two weeks. It'll wake me up in the middle of the night. It'll make my eyes water. So when I'm on Zoom calls or Microsoft Teams calls with meetings, it's a little bit embarrassing because it can look like I'm about to start crying. You know, the number of things I've burned both on the hob and in the grill. I mean it's in the tens. So I don't leave anything unattended because you just can't smell it. So yeah, it is frustrating.

Harry - Alongside this phantom smell Claire, also experiences the symptoms of parosmia. Out of curiosity, I asked what she missed the most

Claire - A Lot. Yes. Lots of things. Really. Just being able to smell my home, being able to smell the outdoors if you go outside. You know, I can't smell my partner because we all have - you know, if you put aftershave on. I miss all sorts of food. I can't eat meat. Yeah. There's just all sorts.

Harry - Coffee?

Claire - Coffee. I haven't had a coffee for a year. I long to have a latte. I'd love to have a nice Costa latte, but I can't because when the coffee machine is going downstairs, I have to hold my nose because it makes me gag. So I don't know what it is about coffee and chocolate. Chocolate, I miss the creaminess of a bar of chocolate, a galaxy bar of chocolate just to be able to get depth. So yeah, I can't get any depth in any food. It's so frustrating.

Harry - Claire, it sounds like you are speaking of a lot of people's worst nightmares there really.


32:42 - COVID-19: loss of smell and taste

Cases of smell and taste disorders have soared during the pandemic...

COVID-19: loss of smell and taste
Carl Philpott, University of East Anglia

Carl Philpott is professor of rhinology and olfactory at University of East Anglia, he even established the first UK smell and taste clinic. Throughout the pandemic he has seen a dramatic increase in patients, some of which are surprising. He tells Harry Lewis and Julia Ravey what he has witnessed over the past two years and what new research is on the horizon... 

Harry - Carl, can we start off by trying to distinguish between taste and flavor?

Carl - Yes. So flavour is really the combination of smell and taste together. Whereas taste, from a medical perspective, is simply what we experience from the tongue and the other locations of taste buds in the mouth and throat.

Harry - And is there a way for us to do this in the studio for us to distinguish between these two?

Carl - Absolutely, yes. So we can do something called the Skittle test.

Harry - I have a big pack of Skittles here with me. Let me quickly hand one over to Julia as well, whilst we're here: it’d be rude to leave her out. What do we do next, Carl?

Carl - Okay. So the first thing is to pinch your nose so that there's no air flowing through your nose. And then when you've done that you can place the Skittle inside your mouth. Let it sit there for five to 10 seconds just to sort of start dissolving and get an idea of what it is you're tasting.

Julia - Sugar?

Carl - Sugar. Yeah. It's very sweet. Isn't it?

Harry - Very specific to one part of my tongue as well.

Carl - If you release your hand from your nose to let the air flow through your nose, you should now experience what the flavor of the sweet is.

Harry - Oh yeah. It's fantastic. I've been waiting to eat these all show as well, Carl. So suddenly I'm getting that blueberry-ness come through and it's fantastic. What about you, Julia?

Julia - Yeah. Yeah, the orange is there.

Harry - It's around the whole mouth as well. That's what I'm experiencing: it's not just on the tongue, but it's actually kind of coating the inside of my mouth.

Carl - What's happening now is you've got a process that we call retronasal olfaction taking place. That's basically the smell of the food inside your mouth, and you're breathing it back out through your nose from the back of your mouth. So it's the reverse of when you sniff things from the outside.

Harry - And for people with parosmia what's happening?

Carl - For parosmia obviously they're getting the same signal that you and I would get in normality, but the information as it's picked up in the smell receptors is then being interpreted incorrectly. We think that's largely because some of the smell receptors aren't working properly, so you're only getting part of the jigsaw. It's always unpleasant generally, unfortunately. I don't know why it's unpleasant. A few people get pleasant parosmia, but most people get unpleasant parosmia.

Harry - Now that you're saying a few people are getting it. How many people are we seeing, since COVID began, develop these symptoms? Is it a lot?

Carl - It is. Of the people who get infection with COVID-19 about 60% get smell and taste loss as a symptom. Of those about 10 to 15% go on to have persistent symptoms that last more than four weeks. So if you multiply that by the number of infections we've had in the UK so far, we're talking somewhere close to a million people. Of those million people, we think about 50% of those, based on the work of our global studies, are getting parosmia: this smell distortion. If you look at them six months on from the time of their original infection, increasingly we see more and more younger people and now children being affected by these smell disorders. And for the first time I've been seeing teenagers in my clinic, which I've never seen teenagers with viral smell loss in the last two decades. So that's already a new phenomenon that COVID has produced.

Harry - How many are we talking about?

Carl - Well, I could only say one or two a month at the moment, but given that I'd never seen them before that's quite significant. And also through our charity, Fifth Sense, we get a lot of people getting in touch with the charity, looking for support, and again, the parents of children and some are even under the age of 10. So it's surprising how young some of these people are being affected, which is incredible.

Harry - I wonder what people that are suffering can do. I know there's been a lot of talk about smelling oils and I have a short clip of Claire again, giving it a go at home.

Claire - One thing I've been doing since I lost my smell and taste, probably about six weeks in, is smell training. So I basically just purchased a set of 20 oils, essential oils from Amazon and effectively what I do a couple of times a day, morning and evening just take short sniffs off each of the oils. I guess when I have bad weeks, I tend to not do it so often. And when I feel a bit more focused then I do sort of try it. The one thing I find discouraging is that I rank the smells, the bottles in the box, based on how well I can smell them. And it's interesting that over time, very few have moved up the scale and most of them have largely stayed in the same ranking. For example, smells like bergamot, rosemary and ginger I can't really smell in the essential oils. Then cinnamon, clove, eucalyptus, and lemon grass are probably the strongest sense. I also wander around the house, smelling things from the herb shelf; I'll smell toiletries, and there are certain things I'll sort of keep smelling just to sort of check back in. I must admit, I do get quite excited when I get a bit of a stronger smell because the one thing I have noticed is there's not much depth in a lot of the smells. So when I do find something that there's some depth in the joy, it's just unbelievable. I just try and continue to do this as regularly as I possibly can.

Harry - That was Claire there talking about the different essential oils that she's been smelling. Carl, for those people that are suffering, is this something they should be doing or is there certain treatments they can be doing at home?

Carl - So, yes. Smell training is an established rehabilitation technique that's had good evidence over the last 10 years. It doesn't work for everybody, but it's worth a try because it's simple to do. And the key message is you don't need to go out and buy anything expensive to do it. The things in your cupboard can be used to help you do it. The central message is four things, twice a day for one or two minutes. They should be things that you were familiar with before you had your problem. If you go to the Fifth Sense website, our charity's website, there's lots of information there about how you can go and do this on a simple and easy basis every day. But it's sticking with it. You've really got to stick with it for up to a year. In reality, the real studies show that the benefits come from longer-term determination with the technique and changing the smells every three months.

Harry - Carl, Claire wants to know she's been now with an altered sense of smell for a year. Is phantosmia something she's likely to have to live with the rest of our life?

Carl - These smell distortions like parosmia, and phantosmia tend to be self limiting. There is a range, but they do tend to get better with time. So they tend to sort of fade out. I'm always talking to people about, once the problem's gone beyond three months and it looks like it's a fairly established problem, then it's worse engaging with treatment, whatever that treatment may be. The biggest problem we have in this field is that there's a real paucity of good quality clinical trials to underpin any treatments. So most of the things that have been tried have been done so in studies that don't really have the sufficient scientific rigor, and that's one of the things I'm trying to correct. So it does tend to get better, but it is pretty miserable while people are experiencing it.

Harry - And Carl, is there any other research on the horizon that people might be using for treatment in the future?

Carl - Yes. So we are just about to start a trial using Vitamin A drops and that's a three month course of treatment. We're looking, compared to a placebo, to see if there are changes in the brain in the areas where smell signals are received as a consequence of doing so. Hopefully we'll take that into a further trial if that's successful.

Harry - Why Vitamin A?

Carl - The retinoic acid component of Vitamin A is potentially involved in the DNA repair process, allowing the receptor cells to potentially regenerate.

smell testing

40:40 - Smell testing

Measuring our sense of smell could help us identify diseases early...

Smell testing
Valentina Parma, Monell Chemical Senses Centre

Smell is a major part of our lives. Here to discuss why we take it for granted is the chair of the Global Consortium for Chemosensory Research and Assistant Director of Monell Chemical Senses Center, Valentina Parma speaking with Naked Scientist Julia Ravey... 

Julia - To circle around to what Claire said earlier, I was surprised that the two things she misses before she even mentioned food were her house and her partner. What are the main things that smell is used for that we don't commonly think of?

Valentina - That is a very good question and can be quite common among people who lose their sense of smell or experience distortion to notice these things for the first time. We can really think about the support of eating behavior and nutrition in general. So smell kind of tickles our appetite and allows us to appreciate, as Carl was saying, all of the differences in the foods that we are eating and we are enjoying generally. The second big important function is warning and protection from hazards that we find in the environment. A simple thing that may have happened to most of us: you have a curtain of milk in the fridge but you don't know when exactly you opened it and you use your nose to detect whether it is spoiled or not. And the third one, which may be the most surprising, is social communication. Imagine the odor of your partner, as Claire was saying, it's infused with some positive and familiar sensations of memories. It's a calming effect. But social communication doesn't stop with mating and finding a partner, a good match in the modern world, but it also refers to newborns and mothers and bonding at the very early stages of life. Because we do know that the sense of smell is one of the most functioning senses at birth and even prenatally. It's fully developed in utero.

Julia - Claire also mentioned how depressing it can be. She said to Harry that before the pandemic she was never anxious, but now she's prone to bouts of anxiety. Is that normal? Do a lot of people suffer from that?

Valentina - Yeah, unfortunately it is. When we look at the brain and where the olfactory system is, then we also understand why. The olfactory system is tightly connected with the limbic system and the connection in particular between these olfactory bulbs that I mentioned is linked with depressive symptoms. So when people then tend to have a reduction in the size of the olfactory bulb, they also tend to show more depressive symptoms. We do see in people that improve their levels of depression, their factory abilities also increase back again. So we can see that there is a tight link with, in particular, depression,

Julia - We were wondering, is there any way in which she can improve her mental health?

Valentina - Self-Compassion is a big part of this process. Keep working on your sensory training and keep monitoring your sense of smell so that you can detect like the tiniest changes in the positive direction. Know that you're not alone. There are plenty of other people unfortunately in your situation at the moment, and then give yourself a pat on the back because you're putting a lot of effort in trying to improve this situation that, if you had control over it, you would not be in.

Julia - And just briefly is our ability to smell something that we should be paying closer attention to? And if so, how should we be monitoring it?

Valentina - This is a very good question. Usually we do not think about our smell in our day. We saw this was very important in the COVID 19 pandemic. It took a long time to put the sense of smell among the symptoms to look for. So with colleagues at the Monell Chemical Senses Center in Philadelphia, we developed a rapid test, the SCENTinel, that helps us actually detect very quickly what is the function of different aspects of olfaction? Usually we think “can I identify the odour that I'm smelling?”, but this is not everything that the olfactory system can do for us. We are using SCENTinel with the idea in mind of proposing universal smell testing. I'm pretty sure that all of us, or most of us have been tested for vision, for audition, at least in our lives, but doctors propose to us to do a smell test, to check on our wellbeing and our health. So our idea at Monell is to have a smell test that is rapid. The SCENTinel takes one or two minutes. It's really fast. It's easy to do. People can do it on their own. This can actually help us monitor the changes in our sense of smell. This is going to be very helpful in detecting several diseases down the road.


46:49 - Cooking with an altered sense of taste

Life Kitchen is a cookery school for people whose taste has been affected, here's a recipe to try at home!

Cooking with an altered sense of taste
Barry Smith, University of London, Ryan Riley, Life Kitchen, & Claire

For those suffering with cancer, neruological disorders, COVID-19 and head traumas, eating can become a chore. Harry Lewis caught up with Barry Smith and Ryan Riley from Life Kitchen to find out how those suffering can inject some joy back into food... 

Ryan - When I was 18 years old, my mother was diagnosed with small cell lung cancer, and I was her primary carer for two years. There was just this moment towards the end of her life, when treatment was really the only thing keeping her alive, where food just became a necessity, but not one that she cared to indulge in. All of the taste was gone. There's this famous story of us all at family lunch where she bit into an onion where she thought it was an apple and she couldn't tell the difference. It was that bad for her towards the end. And then at the same time, I met Professor Barry Smith, and there was just this element where I thought, I think if we launch something together where we do a cookery class, it could be a really exciting moment to help someone rediscover their love of food in that little bit of pleasure.

Harry - Ryan and Barry wanted to create somewhere or something that could help everyday people who are suffering with smell and taste related conditions, to be able to find affordable everyday alternatives, their workarounds. They won't restore the previously experienced flavours that have been lost, but they may allow those suffering to explore new ones.

Barry - One of the things that is always there is texture and temperature. And so again, this is something that Ryan has experimented with contrasts in temperature, contrasts in textures. Those will still make what would otherwise be a very boring and dull eating experience a bit more interesting. One of the things that really is the sort of major tool to use is the use of foods with umami. Umami is of those basic tastes along with salt, sweet, sour, and bitter, which a lot of people in the west don't recognize. In Japan, umami would be as obvious as salt or sweet. You know, the dishes that have it, they can be mushrooms, they can be tomatoes, they can be Parmesan cheese. So there's a huge range of things. Think of soy sauce. That's that meaty taste we get in it, which is not just saltiness it's meatiness and you get that in mushrooms. You get that in soy sauce that is umami.

Harry - This lone word from Japanese is hard to translate directly into English, but suggested equivalence includes savoury, essence, pungent, deliciousness, and meaty is also said to involve all the senses with connotations of emotion and spirituality. One thing we can be certain of is that both Barry and Ryan are obsessed with it.

Ryan - So one thing I will never stop talking about, because if you want to add more flavour to your food, whether you're living with cancer or Covid or any other reason, just get that umami hit in there. Add some Marmite, into your spaghetti bolognese, add a bit of miso into your mayonnaise on a sandwich. An egg mayonnaise sandwich with some miso through that meal, just adds that real beautiful savoury kick and a touch more saltiness and salt is often really demonized in life, but actually it's the difference between a good and a bad dish. Umami is the difference between a good dish and an excellent one.

Harry - That being said, Ryan, that's what we're gonna do right now. You've got a recipe lined up. We've got the potatoes in the pan. They've been bubbling away. What are we doing at the moment, what's in front of us?

Ryan - See this for me is my favourite dish in the whole book. It's called miso, bit of potatoes with a green chilli vinegar. Now, when we were talking earlier about how you can't have recipes with garlic and onions at the core, that would scare most people, but actually it's the key again. If you can add a base, if umami rich like beginnings, then you'll really kind of not miss the garlic and onion base. So for this, we've got some beautiful, new potatoes and they're lovely and hot. I've just drained them, going to drop them into the pan. And then we're gonna do like a classic bit of cookery by just adding a lot of butter. It is really an important part. We're gonna get some miso in there. Now miso comes in so many different forms. It's brown, it's white. It's red. But at the core is, this beautiful, like fermented soybean. And it might end up a little bit more the thing about cookery and the thing about when you've lost your sense of taste, you are looking at how you can adjust for personal preference.

Harry - So kind of forget the ingredients book, start from scratch and kind of go back to cooking at its core. You figure out what the guidelines are.

Ryan - Yeah. Nigel Slater once said that a recipe you should cook once or twice, and then you should go off on your own because if you get the basis in, you then realize what works for you. You know, both me and you standing here now have different tastes. So how can a recipe fit that? So you get that core and then suddenly you've got the basis, just don't swap out the miso. And now just about to add a little bit of soy sauce and a little bit of pepper. So that's three types of umami already, and it's not like we've used anything that unusual, smashing it down there just to really get those flavours in. And so we're gonna be moving onto this green chilli vinegar. And that again is playing into so many of our other senses and it starts by chopping some coriander, parsley and mint.

Harry - In goes the chilli.

Ryan - I'm gonna get this into a ball now. And now the favourite part here is we're going to use really cheap malt vinegar. So we've got all those herbs. We've got that vinegar.

Harry - In they go.

Ryan - And I'm going in, we're using lots of it here. And I think we should serve this up.

Harry - I think we should serve it up Ryan. Great idea.

Ryan - We should, but I'm gonna give you one warning. When we tested it, there was a lady who had COVID and her housemate didn't. She loved this dish and her housemate said it was so strong that it nearly blew her head off. <laugh>. Now the thing for me is I love flavour. I love powerful, real, amazing flavour packed food. So I hope you can handle it.

Harry - I can't think of a time that I've ever tasted malt vinegar in that way. And in that manner.

Ryan - It adds to it. It's not just the seasoning of the potato. Yeah. It really brings together the whole dish. It has a new dimension.

Harry - It is that malt vinegar slightly different, but it hits the palette really strong at the beginning, but that flavour lasts. And I don't, I don't think that's too much that hasn't blown my head off. I'm gonna go in for more.

Ryan - It has blown your mind, right?

Harry - It's blown my mind. I mean, it really was powerful. The team at life kitchen had put together a book of simple recipes designed around those who are burdened with parosmia, but live in the usual fast paced lifestyle that we're all used to. It's called taste and flavour, and it's free for all those who need it. You can download a digital copy online, which will also help fill you in on what's happening to your sense of smell and taste. Armed with this compact little recipe book, I went back to Claire and asked her to give one of the recipes a go for me.

Claire - So I tried the cherry and almond tartlets.

Harry - And we were chatting over text and it was because you fancied something sweet, didn't you?

Claire - Yes. Yeah, yeah.

Harry - And how did it work out?

Claire - So I mean, I guess the recipe was really sort of easy to make. The only thing I would say, I got the slightest hint of taste with the cherry. Yeah. While the syrup was cooking, I could sort of smell a little bit, you know, I could smell the orange coming out in it and I thought, oh, this looked quite good. But, yeah, the finished product, I could just taste a bit of the cherry, in the sort of, in the tart. But yeah, I mean, I didn't let it put me off and certainly I'm gonna try the lemon and zaa'tar feta twists I think. So I'm gonna have a go at them this weekend, but my other half said it was really tasty, so it didn't really help.

Harry - Maybe it didn't work out for Claire on this occasion, but that's okay too. As Ryan mentioned, we all have unique differences when it comes to our sense of smell and our sense of taste. Claire did tell me that she's not deterred, she's buying the ingredients for the corn soup and potato dish that I'm so fond of. And I think her honesty throughout this process has been fantastic because if you're suffering from a similar condition, you'll know probably all too well, it doesn't always work out on the first go, but it might on the next.

Hubble Telescope image of distant stars showing diffraction artefacts.

56:06 - QotW: Why do stars twinkle?

Twinkle twinkle little star, how we all wonder what you are.

QotW: Why do stars twinkle?

James Tykto interviews the bright Dr Jenifer Millard from the Awesome Astronomy Podcast to find the answer to this question...

James -  Well Michael, if ‘Twinkle Twinkle Little Star’ is anything to go by, you’re not the only one wondering what they are. Fortunately, Dr Jenifer Millard from the ‘Awesome Astronomy Podcast’ is here to help us figure that out.

Jenifer -  Stars twinkle only to those looking at them from Earth – in space, their light would be steadfast. They twinkle due to turbulence in our atmosphere which can be caused by wind, hot air rising or cool air sinking. This turbulence changes the starlight’s path from a straight line, causing it to bounce and bump around the atmosphere.

James -  Though we might enjoy gazing at shining stars, our atmosphere can make it difficult for astronomers to observe them. This problem can be solved by using equipment located in high altitudes, or even in space. For grounded telescopes, however, astronomers have a clever way of countering the turbulence.

Jeni -  By using lasers, we can create fake stars in the sky & compare them to the real stars in the sky. We can then use this information to try and account for all the atmospheric turbulence causing stars to wobble about in real time and give us much sharper, crisper images.

James -  So that explains how they twinkle, but what about the colour of a given star? Well, according to Jeni, that’s caused by their respective surface temperatures.

Jeni -  Most common stars in the night sky exist by fusing hydrogen into helium, we call these ‘main sequence’ stars. Just like when we heat metal, and we see it go from red hot, to orange, to white, the fusion inside the star heats up the surface area and produces the colours we see. Redder stars are comparatively cool, yellow are warmer, and blue the hottest.

James -  So the stars that have lots of these fusion reactions within them produce a blue colour on their surface area, whereas the cooler stars that have fewer fusion reactions glow red.

Jeni -  It’s true that more massive stars have greater gravitational forces trying to crush the molecules together, and so must burn through their hydrogen fuel more ferociously, making them hotter. However, once a star runs out of hydrogen fuel, this mass-temperature relationship breaks. Very big stars like Betelgeuse appear red because they have used up all the hydrogen to react with. Their new fuel source makes them puff up and cool down.

James -  There you have it. Stars twinkle because of our atmosphere getting in the way of the light they emit, and the colours are based on the reactions going on inside them. Michael, hopefully, we’ve put that lullabye to bed for you. Next week, we’ll be tackling this question, from listener Daniel.

Daniel -  'How do they stop the mirror on the Hubble telescope from getting dirty?'


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