Should You go Vegetarian?

What would a more plant based diet mean for us, and the planet?
29 September 2020
Presented by Chris Smith, Adam Murphy
Production by Adam Murphy.


A wicker basket filled with an assortment of different vegetables


With an eye on World Vegetarian Day we’re looking at the feasibility of a reduced meat diet: What can cutting down calories from meat do for our health, and the health of the planet? Plus, in the news, a new 20 minute test for COVID, why hybrid cars turn out to be worse for the environment than their official performance figures claim, and after hundreds of elephants mysteriously died in Botswana, researchers now think they know why…

In this episode

a picture of a medical swab

01:03 - 20-minute COVID test

A new test to detect coronavirus in record time

20-minute COVID test
Stephen Bustin, Anglia Ruskin University

Recently Boris Johnson announced an ambitious plan, which he dubbed his “moonshot”, to test our way out of the Covid crisis and back to normality. But the price tag of this proposed multimillion scale daily testing regime is nearly as much in itself as the cost of running the entire National Health Service. Unsurprisingly, many are sceptical, not least because some of the technology needed to deliver it does not exist yet. So you’d think that a new coronavirus test developed by Anglia Ruskin researcher Stephen Bustin, that delivers a result in just 20 minutes, would have health secretary Matt Hancock rubbing his hands together and offering to help. But, as he explained to Chris Smith, that’s not been his experience...

Stephen - We have developed a test that is much faster than anything that is available at the moment. Instead of taking an hour and a half, our test takes 15 minutes.

Chris - Goodness me. Now tell me how it works.

Stephen - You would spit into a test tube, and we would spend about five minutes extracting the genetic information from the virus. That genetic material is a chemical called RNA, which we cannot use in our test. We therefore have to convert it into a second chemical, which is DNA. That DNA is then put into our test, which is a PCR based test. And it copies the DNA copy that we have made several million fold, which we then can detect using sensitive instrumentation.

Chris - This is very similar though, to what is going on in diagnostic laboratories all over the world, except they're taking hours to do it. Why are you able to do it in 20 minutes? How have you done that?

Stephen - Well, firstly, our test detects more than one viral gene. We look at three viral genes. Secondly, we have used a better method, a faster method. Most labs use methods that are 30 years old. They take a long time to convert the viral RNA into DNA, and they take a long time to do the test itself. We have streamlined this to do this in 30 seconds. And then one second, and one second, bursts.

Chris - Interestingly, you said you're using saliva. This is not routinely being done though, is it? Most people are familiar with having what feels like a brain biopsy, with an enormous, great long thing being rammed up your nose and swapped into the back of your throat. So why saliva?

Stephen - Well, saliva is obviously a lot more easy to get hold of. You spit into a tube and this then allows you to extract your nucleic acid from that saliva sample. Saliva is as good a sample as a swab, and in some instances, in some papers suggest that it is even better.

Chris - So if one does a head to head between what we're currently doing in diagnostic laboratories across the country, and your new method, does it perform at least as well, or possibly even better than what we're doing at the moment?

Stephen - The test itself is better than what people are using at the moment. Out test can detect a single copy of the viral genome, and we tested our tests on samples from Broomfield Hospital. And we found that in every single case where the hospital had a positive, we had a positive, and in every single case where they had a negative, we had a negative.

Chris - Could you use the existing machines and platforms which are running across the country, and in fact, across the world, to introduce this test, or does this need a whole new load of equipment, and a whole load more expensive training before it could be launched?

Stephen - No, this test will work with any instrument that can run real-time PCR.

Chris - Have you spoken to the people who are in charge of testing in the UK?

Stephen - Yes. We've done two things. We applied for funding from Innovate UK, and we had four referees, and they all gave it very high ratings, but it wasn't funded. I then went to my local MP, and talked to him who put me in touch with the health secretary. The problem is that unless the test is CE marked or FDA approved, it is very difficult to get it accepted rapidly. And as a university, we don't have the facilities to do a proper CE marking for example. So it is not easy to introduce a new test like this.

Chris - What you're saying is then, that bureaucracy is effectively getting in the way of a test being introduced that could in fact be an order of magnitude faster than what we can do at the moment?

Stephen - It's one problem. Yes.

Chris - What did Matt Hancock say?

Stephen - He put me through to Lord Bethell, who then put me through to somebody else, and it wasn't a totally satisfactory interaction.

Chris - Oh, and what grounds were they giving then? Were they just saying: You have to go through the right channels and just go away. I mean, that's not very constructive, is it?

Stephen - There's no easy and fast Dragon's Den type approach to pitching something, and then getting funding for it.

Chris - How much do you think you need Stephen, to actually get a CE Mark? This is, and for people not in the know, this is like a badge of honour that says this meets, or passes muster, isn't it? A CE Mark says, this is a tried and tested, validated, quality assured test. That's what you need, isn't it? How much is that going to cost, do you think then to get that?

Stephen - It's not just the question of cost, it's a question of, we're not set up to do that. So what I would like to happen is, for a manufacturer to get in touch with us, or for us to be able to get in touch with a manufacturer, and get them to do it with us. And that's what we're trying to do at the moment.

Chris - Okay. Well, we will throw down the gauntlet to people listening to this. And if anyone would like to get in touch, who do they get in touch with, to say to you, we'll take your pain away and we'll get this test out there.

Stephen - I can give you my email,

A fuel gauge for a car

07:02 - High emissions from hybrid cars

Drivers don't drive them they way they do in the test centre...

High emissions from hybrid cars
Richard Black, Energy and Climate Intelligence Unit

Hybrid cars are a significant slice of the automobile market. These vehicles claim to cut emissions, they’re incentivised by lower levels of tax, and are cited as a cornerstone to cut our carbon footprint. But new research from Transport and Environment, and Greenpeace, which followed 20,000 hybrid drivers, suggests that in real world usage, the emissions from hybrids are up to 2.5 times higher than the tests would have you to believe. Adam Murphy spoke to Richard Black, who’s the director of the Energy and Climate Intelligence Unit, who wasn’t involved in the study, about why there could be such a big gulf in the numbers…

Richard - The mismatch seems to be the testing. It doesn't take place in real world conditions. And so you can test them in a lab, where you can go out on a test drive and that's fine, but actually people don't always use cars as they do in a test condition. And I remember there was actually a study out a couple of years ago in the UK, which looked at the behaviour of company car, hybrid drivers. So people who've been given a company car that was a hybrid. And what they found was that a lot of those drivers weren't actually using the electric components of this at all. They were simply driving around using the petrol engine. And then of course, if you do this, your emissions are not going to be lower than they would be from just having the petrol, or engine itself. In fact, they might actually be higher because you're lugging around a big battery and so on, that you're not using it's just extra weight.

Adam - So what happens then, just for a bit of background, in those kinds of testing conditions that makes them so different from how the real world is?

Richard - Obviously the tests are done in an artificial situation. So you can go out on a test drive, whatever it might be, a 20 kilometre drive, but the driver knows why they're doing that drive. Sometimes the motor industry conducts tests in the laboratory, where the cars are mounted up on rollers and you fit a hose over the exhaust pipe, and you catch emissions there. But again, your driving behaviour will be changed by the fact that you know that you're in a test. What's also emerged a few years ago, when we had the so-called Dieselgate scandal, was that at times, the testing labs, they seem to have a slightly unhealthy relationship with some of the car companies. Now, I don't know if that's the case in this instance with the hybrid test, but you know, that's something that I see that is there in the history of motor manufacturing in Europe. So I think the main reason is though the behavioural one. We all know, for example, when we jump in a car, we know that the emissions are going to be highest when the engine's cold and we should sort of warm it up. We don't always do that because sometimes we're in a hurry. We don't always drive as the old driving instructors used to say, as though there's an eggshell between your right foot and the accelerator pedal to conserve gas, we accelerate sharply, we brake sharply, we do all these things. So that's why this real world data, I think is so interesting.

Adam - Would you be able to tell me a little about the new policy decisions?

Richard - The hybrids question matters in the context of a policy that the British government is expected to make in the next couple of months, which will be, basically, a ban on the sale of new petrol and diesel engine cars. It's going to set a date when that ban will come in. The date could be as early as 2030, it could be as late as 2035. And basically, the main reason from climate change terms for doing this, is because transport emissions in the UK haven't been falling. This is an obvious way to do it. It's an absolute no brainer. If you want to get to the net zero target, there are calculations also suggesting it would be good for UK GDP. There's a whole range of businesses that are behind this. So one of the questions is then, do include hybrids in this ban. And the government has been subject to intense lobbying from parts of the UK automotive industry, which make hybrids, and have invested heavily in hybrid drive trains, to say that hybrids should be allowed. But obviously what this new research does is to say, well, hang on a moment. If hybrids aren't actually much cleaner in real life, than normal petrol diesel cars, why would you allow them to be continued to be sold after this ban comes in? Why wouldn't you go straight for pure electric cars, and pure hydrogen powered cars as well? So that's why I think this finding coming as it is, is particularly important, because it does very much play into the logic of this decision that the UK government is expected to announce in the next couple of months or so.

A small river running through a mossy, forested area

12:44 - Pollution in UK rivers

Only 14% of UK waterways are considered "healthy"...

Pollution in UK rivers
Janina Gray, Salmon and Trout Conservation

Rivers, streams, and lakes are an important part of the landscape, not just owing to their aesthetic value, but because they provide much of our drinking water. Alarmingly though, a new survey has delivered a damning verdict on the health of these water source, as Eva Higginbotham found out from Janina Gray, from Salmon and Trout Conservation…

Eva - It is a sunny and windy September day. And I'm down by the river Cam in Cambridge. There are a lot of very excited ducks. Some swans, even a baby swan. Well, a teenager really. And of course the river itself. Even with summer coming to an end here in the UK, there are still a lot of people on the riverbank. And in high summer, the riverside is a popular spot for picnics, punting and even swimming. But despite this idyllic scene, a recent report by the Environment Agency revealed that there is more going on below the surface, and it's not good news. Earlier, I spoke with Janina Gray from Salmon and Trout Conservation to understand what's going on.

Janina - The results which came out last week are the water classification results according to the water framework directive, which is a piece of European legislation, which looks at the health of all our water bodies. So our rivers, our lakes, our streams, and basically classifies them according to their ecological health and also the physiochemical health of the water body. And clearly the results last week were not very good. All of our water bodies were failing good status, and that's because all failed for chemicals, and only 14% were healthy according to their ecological attributes. And that's things like the fish, the plant communities within the rivers.

Eva - That just seems to be an incredibly poor score. Where do these chemicals come from?

Janina - So it's a wide range of places. Obviously agriculture is a major problem. So farmers will spray pesticides on their land to obviously kill bugs and they'll spray phosphates fertilisers basically to help the plants grow. And if this is washed off via rainfall into the rivers, that's when it starts causing big problems. So obviously pesticides, you know, they will kill invertebrates in the river, they will cause disruption to fish. And phosphates in the rivers basically can lead to excess algae growth, which basically sucks up all the oxygen from the water body and chokes out wildlife. There's also pharmaceuticals. So from things being flushed down the toilets and going into the sewage system, and then obviously ultimately ending up in rivers and, you know, run off from industries as well. Um, it's really across the board.

Eva - Do you know how they actually carried out the survey? Did they literally go to every single river, stream, lake around the whole of England to get these data?

Janina - It's not possible to survey everywhere. The Environment Agency has a monitoring network, which they then fill in the gaps by modeling and anybody who knows modeling will know that the models are only as good as the data that goes into those models. And unfortunately, like with a lot of things across the board from the Environment Agency monitoring has also been cut.

Eva - What do you think we need to do? What can we do about this?

Janina - So there's some really quick wins that we could do, or the government could do. Ultimately at the moment, a lot of the pressures facing our water bodies are coming from agricultural sources. The regulation is already there. We have something called farming rules for water. We've got slurry regulations, but the Environment Agency does not have the resources to basically enforce this legislation. And by just enforcing that legislation, it can make a dramatic difference. It could reduce the phosphates that are coming in from fertilisers. It could use the chemicals coming in from pesticides, could reduce the sediment reaching our rivers as well, which is bringing in a lot of other nasties with it.

Eva - And is this just a UK problem?

Janina - The European Environment Agency did do a report and they found that on average, it was about 40% of water bodies were reaching good ecological status across Europe. And the countries that were failing were the kind of heavily industrialised countries, or basically more populated countries. So countries like Belgium, Germany, the Netherlands, and of course, England were fairing the worst.

Eva - And just to play devil's advocate, why does it matter if the rivers are unhealthy?

Janina - It affects all of us. I think that, you know, from coming out of COVID, we've all realised that actually green spaces, blue spaces, are really important to our wellbeing, our health. And obviously these chemicals, they will affect invertebrate communities, which are the base of the food web, they'll in turn affect fish and all the other associated wildlife that we love. And that we care about. Kingfishers, otters. So it's a wellbeing thing for all of us and obviously intrinsic value of nature that we need to protect them. But also the more chemicals, the more pollution that's going into water bodies, the more basically our water companies have to pick up the cost to remove them and ultimately, you know, that's us. So we're paying twice really. We're paying to clean up the act of industry, of farming. And also we're losing biodiversity. We're losing these really iconic species.

Elephant in Botswana

18:00 - Explanation for elephant dieoff

After hundreds of elephants died suddenly in Botswana, poisoning by toxic algal blooms appears to be the cause...

Explanation for elephant dieoff
Vicky Boult, University of Reading

Back in July, we brought you the tragic news of a mass elephant die-off in Botswana’s Okavango Delta: hundreds of the animals were found dead. Originally, the cause was unknown, but, this week, Botswana’s Department of Wildlife and National Parks think they’ve identified the culprit: blue green algae in stagnant water. Phil Sansom spoke to conservationist Vicky Boult, from the University of Reading…

Phil - The first of the elephant deaths were reported back in March. Then from May, the carcasses started appearing in droves.

Newsreader - 169 elephant carcasses were found. By June, that number had risen to over 350.

Phil - Some look like they died incredibly quickly, keeling over onto their knees and faces. Others were reported looking disoriented, walking around in circles before eventually collapsing.

Newsreader - This is deeply troubling. Elephants don't just drop dead for no apparent reason.

Phil - For Africa's largest elephant herd, this unknown devastation looked like an existential disaster. Among all the possible reasons that were suggested, from starvation to dehydration, to deliberate poisoning, Niall McCann from the UK charity National Park Rescue mentioned the following on The Naked Scientists -

Niall - The least likely is that this is a natural toxin. Something like anthrax or a blue-green algae. If it was any of those things, we'd be expecting to see many other species also coming as well.

Phil - Well Botswana's government have just announced that this is indeed the reason.

Vicky - Tests have revealed that it is a cyanobacteria, which is a blue green algae that lives in water bodies.

Phil - [That was] elephant conservationist, Vicky Boult.

Vicky - Cyanobacteria are in many water systems across the world, but they become toxic when they bloom. We call it an algal bloom, which is just a mass generation of new cells, new bacteria. And we see these like blue, green scummy layers on top of water bodies, which is why it's called blue green algae. Usually that water body should be quite warm and nutrient rich and also slow moving or stagnant.

Phil - There's certain types of this blue green algae, this cyanobacteria, that produce neurotoxins. Toxins that hurt your nervous system. Make it start to shut down.

Vicky - You might see symptoms such as confusion, muscle weakness, muscle spasms. And that actually aligns quite closely with some of the symptoms that were reported in these elephants.

Phil - Interestingly, these blue green algae may have actually been the cause of some prehistoric mass elephant die-offs, which would be a bizarre turn of events because there's no record of them happening since. Until possibly now. And why here, in this part of Botswana in the Okavango Delta?

Vicky - The area where these elephants have died is very much enclosed from the broader ecosystem. There are fences separating Namibia from Botswana, but also a veterinary fence, which keeps wildlife and livestock from intermixing. The only other water source that's not a small stagnant pond is the Okavango pan handle. But for elephants to access that they have to move through human settlements and through farmland. So that cleaner water potentially is not readily accessible to them, which may have forced them to use these toxic water bodies.

Phil - No other wildlife species on the planes were affected by this toxic water. And even scavengers like hyenas and vultures that we're seeing feeding on the elephant carcasses showed no signs of illness.

Vicky - There's a couple of possibilities why we're not seeing that. Firstly, it might be that just due to an elephant's sheer size, they drink a huge amount of water and perhaps it's the amount of water and therefore the amount of toxins that they're ingesting. The other option is that elephants and elephant carcasses are very well monitored in Africa. And so it's possible that actually we're recording these dead elephants and not recording anything else because other things are harder to survey or less important to survey.

Phil - Both of these are just theories at the moment.

Vicky - I have seen a lot of people online, still quite skeptical. And I think that's mostly based upon the lack of transparency in the reporting from the Botswanan government. We have very little idea of exactly what samples were taken from the elephant carcasses, but also from the water sources and the broader environment. But we also haven't seen the pure lab results.

Phil - Like we reported last time on the programme when we covered this story, this is bad news for elephants as a whole, because back when researchers just didn't know what this was, there was a worry that this could sweep through the whole of the elephant population, and become their equivalent disaster while coronavirus sweeps through us. If it is the blue green algae, though, then we might hope that this is a limited area, not going to happen now that the temperatures are going down. But if this indeed is something that happened this summer because of warmer temperatures, then who's to say it won't happen next summer or the summer after that?

Vicky - It might be that we've seen the perfect climatic conditions for causing these blooms. Potentially a worry as we're moving into a warming world under climate change, we might start to see some of these algal blooms happening more often.

A plate of salad, surrounded by bowls of various fruits

24:37 - Why doesn't society go vegetarian?

Why meat-eating is ingrained in our culture...

Why doesn't society go vegetarian?
Kate Stewart, Nottingham Trent University

Surveys suggest about 6% of people in countries like the UK are vegetarian. In the UK, that’s about 3 million people. Looking at it the other way, 94% of the population chooses to eat meat. But why is that? It turns out that it’s probably a behavioural thing that’s programmed into us by our lifestyles from birth, as Adam Murphy’s been finding out, from sociologist Kate Stewart...

Adam - Vegetarianism is on the rise, but even so it's still the minority position. Vegetarians and vegans have plenty of moral arguments, saying things like animals "not being ours to use". And as someone who does eat meat, I find those moral arguments hard to dispute to be honest. But why is meat eating so ingrained in our culture? I spoke to sociologist Kate Stewart from Nottingham Trent University.

Kate - It's something that we do three times a day or more. We eat; we eat together as part of our family units, as part of our friendship units; so changing the normal ways of doing that is actually quite a big task, because it is such a huge part of our everyday lives. I think as vegetarianism, veganism and plant based-diets become more popular, adopted by more and more people, then that process of perhaps shifting becomes a little bit easier, a little less unusual.

Adam - That makes meat eating the default, and the default is easy to maintain. But how are animals presented in society to reinforce that default?

Kate - I think that there's lots of ideas that we have about being special and different and separate from the natural world, if you like; that a way in which we identify ourselves as a species as being important and special is through our sense of dominance, ownership, use of the natural resources on the planet that we live on; this idea that everything else on the planet is there for us to use, and for us to use in order to sustain and enjoy our lives as members of the human species. So from infancy we see messaging about the normality of using animal products, right from the beginning. I mean, if you think about the absurdity of infant milk formula brands referencing cows; the idea that this replacement for human milk is already being subtly messaged as something that comes from another species, and the appropriateness of that. If you look at children's food packaging, mostly canned baby food is rice and vegetables mashed up; you look at the pictures on the front and the description of the meals, it's "Shepherd's Pie", it's "Mum's Roast". It has all of that traditional narrative to it about what a meal is, and favouring the meat part, the animal product part; when in fact if you looked at the ingredient list, that's really not what's in the jar at all! It's mashed up vegetables and rice with maybe a bit of other things for flavouring. So the messaging comes through right from the beginning of life, and then we see it reinforced through how other animals are represented in toys, in games, in film and television, on clothing even. We see this organisation of different species into their appropriate uses to us as humans.

Adam - Some people look down on vegetarians and vegans. There's that old joke: "how do you find the vegan? Don't worry, they'll tell you." But where does that attitude come from?

Kate - I think it's because people see it as being some sort of moral or ethical comment. And it seems to suggest people who aren't vegetarian or vegan feel that vegetarians and vegans are making some kind of suggestion that non-vegans, non-vegetarians, have failed morally; it's some sort of ethical shortfall, that they failed to act on a moral issue, they've failed to do something that vegetarians and vegans have done on an issue of morals. So that prompts all kinds of responses. It can prompt a defensiveness; so you speak to any vegan, they will tell you how common it is for non-vegans to account for their moderate consumption of other animals quite enthusiastically. So that's one common response. But then also quite common is that angry defensiveness turns round as an attack, because it's a response to feeling that their own moral thoroughness is being questioned.

Bowl of fruit

Your health on a plant-based diet
Shireen Kassam, University of Winchester

Is a plant based diet better or worse for us than a meat-based one? And, indeed, does it need to be an all or nothing thing: do we actually need to choose, or would a shift towards a more plant-based diet for at least some of our meals be a good compromise? Shireen Kassam is a consultant haematologist with the University of Winchester and she has an interest in the management of chronic diseases using plant-rich diets. Shireen spoke to Chris Smith in the studio, starting with what her own diet choices are...

Shireen - I eat a hundred percent plant-based diet. So other people would call that a vegan diet.

Chris - Okay. I just wanted to put that on the table - excuse the pun - because that way people kind of understand where we're coming from. Now in what ways do you believe that eating a plant-based diet is better for a person than a meat-dominated diet?

Shireen - Well the science is clear on this: the greater your shift towards a plant-based diet, minimising animal foods and processed foods, the healthier you are; and that's healthier bodyweight and significantly reduced risk of cardiovascular diseases, type II diabetes, and certain cancers. And more and more it's clear that those same risk factors are leading to dementia in later life, and if we got away from our conventional meat-based diet there would be less incidence of dementia in our society too.

Chris - So is that the case, then, that if one looks at populations such as in parts of Asia where meat-based diets are rare, that you see a correspondingly low rate of dementia, and a correspondingly low rate of things like diabetes, high blood pressure, stroke, and heart attack?

Shireen - Sure, if we look around the world where people are living the longest and the healthiest lives - and these regions in the world are called the Blue Zones - people are eating predominantly plant-based diets, 85-90% plant-based. And when scientific studies have been done looking at difference in the health outcomes for omnivores versus pescatarians, vegetarians, vegans; a stepwise reduction in the amount of animal foods you're eating, the better the health outcomes. So the science is absolutely clear on this.

Chris - But if someone says, well actually I quite like eating meat... and I mean, I'm one of them. You'd have to really twist my arm very hard at my back to dissuade me from occasionally frying up a rasher a bacon; it's just something I really enjoy doing from time to time. Would nevertheless a substitution of some plant-based food stuffs in place of a meat dish still translate into a health benefit? I don't have to go the whole hog... that's probably a bad choice of words isn't it! I don't have to go all the way in order to get some health benefit?

Shireen - No, absolutely. You don't have to be a hundred percent plant-based. But I would like to be clear that you can be perfectly healthy eating a hundred percent plant-based diet. So it comes down to a choice, a choice that we can all make, but any shift towards a plant-based diet is going to be better, as long as it's coming from healthy sources of whole plant foods, fruits, vegetables, whole grains; not the processed plant-based foods that are becoming increasingly available. And if you are going to choose your meat, I really would persuade you not to eat a processed meat like bacon, because it is a Group 1 carcinogen, it causes cancer. So make a better choice.

Chris - Whoops. Okay, well that's that off the menu then. But just coming back to the question of being healthier... because one does hear horror stories where you get people who say, "well, I'm going to turn over a new dietary leaf and I'm going to go down the plant-based diet route, I'm going to eschew meat," and then they wind up in their doctor's surgery with raging anaemia because they're not getting enough iron, and they can also get other micronutrient deficiencies. Is that just poor eating habits because they have embraced the lifestyle without knowing what they're doing, or that is there a high risk that this can happen to anybody?

Shireen - Well I think it can happen to anyone on any diet pattern. And as a haematologist I see plenty of people with iron deficiency, and as you've already pointed out, 94% of the population are not vegan or vegetarian; your risk of anaemia is no greater on a vegan or vegetarian diet. We're doing our current diet pattern very poorly. We're fibre deficient, potassium deficient, folate deficient; and we are eating too much protein from animals and saturated fat. A;l diet patterns need careful planning and we've forgotten how to do that. So if you're shifting a diet pattern, you need to do it with the knowledge and skills to do it properly. As you know, a vegan diet needs supplementation with vitamin B12, because it's not made by humans or animals; but beyond that you need to find your nutrients in the same way as you would on an omnivorous diet.

Chris - And how quickly would one begin to derive benefit? Because if you've been eating a lifetime of meat, is it the fact that if I were to switch to an exclusive plant-based... a) that might upset my system for a while, and b) would it actually be beneficial at a later stage of life to do that?

Shireen - Yeah, it's always beneficial to shift more towards a plant-based diet, but it depends on your starting point. As you pointed out, you can be healthy eating an omnivorous diet if you're doing it with lots of fruits and vegetables and other nutrient-dense foods alongside the meat. So you may not feel anything, but if you did need to improve your health as the majority of the UK population do, you'll find that it's easier to shed a few pounds in the first few weeks because you're eating lower calorie density foods which are more nutrient dense. For example, if you do have prediabetes or type II diabetes, within a few days your blood sugars will come down and you need careful management of that. Within two to four weeks, you'll find that your blood cholesterol level, if it needed to be lower, will come down to a healthier baseline. So yes, within a few days, weeks, months. And of course we're all talking a lot about gut health and the gut microbiome; that only takes a few days of shifting to a healthy plant-based diet to show an increase in the helpful bacteria. But it might be if you're feeling well and healthy, you don't feel any benefits; it's just you're benefiting your long term health, and of course the health of the planet too.

chairs and tables in a cafeteria

36:02 - Changing minds about meat

Can people be gently persuaded to eat less meat?

Changing minds about meat
Emma Garnett, University of Cambridge, Chris Davis, Impossible Foods,

What factors drive our food choices and dietary decisions, especially when we dine out, or eat at work? Adam Murphy spoke to the University of Cambridge's Emma Garnett, who is trying to change minds in the university's cafeterias, and then to Chris Davis, research director at Impossible Foods, who are trying to make meat substitutes that fully replicate the real thing...

Adam - We know there are benefits to a plant based diet. And we also know that people don't like change, but is there anything that can be done to gently persuade people to be a bit veggie-er? Emma Garnett from the university of Cambridge looked at one approach in the university's cafeterias.

Emma - We found that increasing vegetarian availability in cafes, so instead of one out of four options being vegetarian, it's two out of four, increased vegetarian sales. And not just in people who are more likely to pick a vegetarian option anyway, but even in the most carnivorous diners, they also became more likely to pick a vegetarian option. It seems that just providing people with more vegetarian and plant based alternatives really helps. Another set of studies we did we wondered, how does the position of meals in cafeterias, how does that influence sales? And so week by week, we swapped putting a vegetarian option nearest the entrance, so this veg-first condition, and putting the vegetarian option further away from the entrance and the meat option first. And what we found was that when there was quite a long distance between those two options, 181 centimetres to be precise, then vegetarian sales increased by between four and six percentage points. However, when the vegetarian and meat options were quite close together, less than 80 centimetres, putting the vegetarian option first didn't really increase sales. And in fact, sales could even be lower. So that was quite surprising and unexpected because there's a very commonly held belief - if you want people to just pick something more, you put it nearer a cafeteria entrance. And we found that that's not really the case necessarily. It can work under some circumstances. So it seems to be the more important thing is about having a vegetarian option being the easiest, being the default option, the least effortful.

Adam - But that's not the only way. There have been leaps and bounds made in meat substitutes, things like meat-free burgers or vegan sausage rolls. Chris Davis, research director of Impossible Foods, is working on making the best meatless meat.

Chris - We started off with a specific mission in mind, which was to replace animals in the food system. And in order to do that, you need to provide a better product that provides more consumer benefits and sell it to people at lower cost. Then if that product also has sustainability advantages, you can make some difference to biodiversity et cetera. So because of that, we started off with a very clear focus on meeting the normal meat-eaters where they are today. So not trying to ask them to eat anything different, trying to make something that looks exactly and behaves exactly like the meat they're already eating. And so, as a result of that, we went back to first principles and said, well, what is it about animal tissue that provides the sensory delight? The way it cooks, the way it transitions, the way it handles - all of those things are important to the social glue that meat provides in a lot of ways. And so what we had to do was basically go back to first principles and identify the molecular ingredients that enabled us to replicate that. And I think that's just a very different approach than any of the previous companies that trade in this field. So let's start with the sizzle! The sizzle of cooking meat - if you think about it, it's critical to your enjoyment of meat, but it really has nothing to do with the animal. It's really to do with the way that the fat and the water leaks from the meat when you cook it. And so by measuring that, we can then say, okay, how do we replicate that behaviour? And so we're able to create a fat mimic and include it in the composite material of our meat that had that same performance of leakage that led to the same sizzle. So when you now cook it on the grill, you get the sizzle, you're cooking it on the barbecue, you'll get the flames coming up when the fat hits the coal. It's all driven by our fundamental understanding of how sizzle works. And basically we've done that all the way through meat.

Adam - And what is Chris's admittedly biased opinion about the importance of meat alternatives, like the ones from Impossible Foods?

Chris - This is probably the most interesting and important scientific challenge that is currently going on in the world is how do you feed the world with delicious, nutritious food in a way that enables us to maintain the planet in a state in which we want to live? So we can maintain having rainforests, that we can make a significant dent in climate change. People underestimate how important the food system is to our impact upon the planet. And we can do so much better if we step aside from the stone age technology of animals. Eating animals made sense as a pre-agricultural society, but from just a straight up efficiency perspective and our ability to feed the 9 billion people or so we'll have on the planet in a few years time, we need a better way to feed people.

A picture of the Earth from the ISS space station

42:28 - Plant-based diets and the planet

What difference would a plant based diet make to our climate change gas emissions?

Plant-based diets and the planet
Sarah Bridle, University of Manchester

It’s not just our own health that can be improved by a shift towards a more plant-based diet, the planet benefits too. Chris Smith spoke to University of Manchester physicist Sarah Bridle, who’s also the author of the book “Food and Climate Change, without the hot air”, about how that shift might help the Earth...

Sarah - Well, in terms of all the cutting down forests, you have to do agriculture on the land and then animals and fertiliser on the fields and so on, and all the packaging and transport and everything, adds up to about a quarter of all greenhouse gas emissions currently coming from food. And that's increasing as there are more people eating more climate unfriendly foods.

Chris - And what fraction of that quarter is meat?

Sarah - It's about a half of that is coming from meat, depending on how you add it up. But yeah, it's half or more.

Chris - And why is meat so high? Because you think well, meet meat, we're going to eat that. So why would meat contribute so many climate change gases?

Sarah - Well, fundamentally we have to grow a lot of food to feed animals. So it takes about 16 times as much land to produce animal-based foods as it does to produce plant based foods.

Chris - Oh goodness. So in other words, what fraction, if you do the sums then, of the total land in agricultural use is just growing food for animals?

Sarah - About 80%. So about four fifths of the current agricultural land is currently being used to produce food for animals.

Chris - That's a lot, isn't it? So that means then if we all went vegetarian, and I'm not for a minute suggesting that anyone would embrace the idea but if we did, does that mean then that 80% of land would immediately be liberated because we wouldn't have to grow food for animals that we wouldn't want to eat?

Sarah - Very nearly yeah. I mean, we'd have to grow a little bit more plants just to make up for the calories and nutrition we'd lose from the meat. But even then three quarters, 75% of the agricultural land would then be freed up and we could use it for other things like maybe forest, for example, for pulling carbon dioxide out of the atmosphere. And that itself would also help to combat climate change.

Chris - You pointed at this when we first began to talk just now when you said, well, actually the human population, although it's only a quarter of our contributions, the human population is growing. So that quarter is growing as well isn't it? So it's continuing as the human population grows to get bigger and bigger and bigger as a contributor. So even if we did all go vegetarian, we'd still end up with food production being a very significant source of climate change gases.

Sarah - Absolutely. I mean, we have to do something about that three quarters, the rest of it. But if we were to stop burning fossil fuels, then food would then be the biggest contribution to climate change. And certainly, hopefully, we can reduce fossil fuel usage and it will be more and more important in terms of climate change in the next decade hopefully.

Chris - And what therefore is our best approach. How do we get a handle on that 25%, is the food industry. To bear down on that? And also if we do switch away from meat towards more plant based diets, how do we keep driving down the contribution to climate change gases from agriculture?

Sarah - Well, I really, really feel that there's not enough information that's easily accessible at the moment. So quite often people will just say, you know, for example, an average vegan diet causes about half the greenhouse gas emissions of an average omnivore diet. We can do these very, very broad generalisations, but actually in detail, of course, some farmers are working extremely hard to reduce the climate impacts of what they're producing. And so actually what I really want to see is labelling of greenhouse gas emissions on all food packets. And then we could actually go in there and reward the great work that's already being done by many food producers, but also that would mean that food producers themselves will be a lot more aware of their climate impacts and would work on that side as well to reduce the climate impacts of what's being produced.

Chris - Are all meats equivalently evil, or are some worse than others?

Sarah - In terms of climate impacts, there's a big difference between different types of meat. So if we look at something like beef and lamb, then they come from ruminants, they've got a particular type of stomach and about 5% of the calories eaten by a cow are burped out. Burps, very important that, not farted out, as methane. And so that's a very potent greenhouse gas. And so there tend to be over 40 times the amount of climate impacts. So if you get 40 times as much greenhouse gas emissions from eating a piece of beef than the weight of that beef, it's relatively high compared to something like say chicken, which is closer to 10 times. So there's about a factor of four difference between something like chicken and something like beef if not more.

Chris - How does dairy fit into the equation then, because obviously you've got to keep a cow to have milk. And therefore another staple of often many vegetarian diets is cheese, for example, which comes from milk. So how do the equations break down and shake down for the dairy industry?

Sarah - Yeah, so that's absolutely true. And in fact, if you, if you were to look at something like cheese, then it actually on average causes more greenhouse gas emissions than chicken. So if you were a meat-eater who ate only chicken and you replaced all of that chicken with cheese, it would actually be on average worse for the climate.

Chris - Hence you're saying, that's why we need the labelling.

Sarah - Absolutely. And it's just not so well known that there's these big differences.

Chris - And it's simple to say, well, I'll just start eating lots of fruits and vegetables, but a lot of that stuff doesn't grow in this country. So when one factors in the carbon footprint of transport, how does that affect things? And would that be reflected in the label on the supermarket shelf? I would say that will be difficult, wouldn't it? Because how would the supermarket know that I'm going to drive to the supermarket to buy that apple or something and therefore add my carbon footprint to it, or would we just have to live with the fact that extra carbon costs are all necessary?

Sarah - There's lots of different ways of doing the climate labelling. For example, often people don't count the consumer, you know what we do as citizens, within that number. So you might not necessarily have your car journey to the supermarket, but inside that label should definitely be all the transport that's happened to get that food to the supermarket. It very much depends on how that food has been transported. If the same piece of food were to come by ship versus by air, then flying it by air causes a hundred times more climate impact than sending it by boat. So as consumers, we don't usually know when we go to the supermarket, which things have come by air or by boat. And so it's really difficult to know, but if you have something that's come by air then it starts to get climate impacts comparable to those of some of the lower, lower impact meats and animal products.

A sweaty forehead.

QotW: Why does some sweat stink more?

This week, Phil Sansom has really worked up a sweat in his efforts to answer listener Margaret...

Margaret - Why, why, why can I work in the yard and be covered in sweat for hours, and only stink a little; but reveal one personal thing to a group of friends, and immediately stink to high heaven?

Phil - I have a rubbish sense of smell and probably a bad sense of shame too; I’ve never noticed this. But Margaret’s touched on some genuine science, and I have two experts here to explain between them: Angela Ballard from the International Hyperhidrosis Society, and University of Cambridge physiologist Christof Schwiening. Here’s Angela first.

Angela - The sweat your body produces when you’re on stage, interviewing, or running late is, indeed, smellier than the sweat produced when you’re working in your garden or exercising. Your body has two different kinds of sweat glands.

Christof - When you get hot exercising, the sweat you produce comes from eccrine sweat glands distributed throughout your body.

Angela - This type of sweat begins after a slight warm-up period and tends to be odorless because it is composed mostly of water.

Christof - Whilst the liquid contains a natural antimicrobial, it provides the moisture that allows bacteria on your skin and in your clothes to grow, producing a 'little stink'. The amount of stink will depend upon what bacteria are present and the sensitivity of your nose to those smells. But a word of warning: others may detect a stronger smell from you under those conditions because they are not adapted to your smell.

Angela - Apocrine glands, on the other hand, are found mostly in your underarm area, genital area, and on your feet. These glands produce a thick, viscous fluid that’s full of proteins and lipids, and respond immediately to stress – no warm-up period required.

Christof - Now fresh apocrine sweat doesn’t actually smell that bad, but it’s more oily than eccrine sweat, and critically it wets regions that are rich in bacteria and odorants. And when you get embarrassed the apocrine sweat wets these regions, and all of a sudden the pong is released.

Angela - And the bacteria that naturally inhabit the surface of your skin love to feed and grow where there are proteins and lipids, and where you have bacterial growth, you have odour.

Christof - Your nose, like everyone else's, is sensitive to it because it gets to smell it, if you like, 'for the first time'. But most people would struggle to detect a 'major' stink under these circumstances. Now it could be that your bacterial population is particularly 'pongy', or it could just be that your nose is more sensitive than most other people’s.

Phil - Thanks to Christof and Angela for helping with the answer. Now don’t run away, because next week’s question comes from listener Charlie…

Charlie - Humans have adrenaline for our fight or flight situation. Do bugs have this too?


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