BONUS: You Might Also Like: "On Point"

We are sharing an episode of On Point with Meghna Chakrabarti. On Point is a rare public space where you hear nuanced explorations of complex topics live and in real time. Meghna leads provocative conversations that help make sense of the world, with urgency, timeliness and depth. In this episode Meghna asks: Could sunlight help treat disease? She details a growing number of studies that find potential benefits of UV light therapy for conditions like multiple sclerosis, Type 1 diabetes and Crohn’s disease. You can find more episodes of On Point at https://link.mgln.ai/shouldknow Learn more about your ad choices. Visit megaphone.fm/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Mike Carruthers?

  Hi and welcome. I want to share something special with you today. It's a podcast I listen to and I think you're gonna like this. It will help you uncomplicate the news and better understand what's really going on in the world. On Point is a rare public space where you hear nuanced explorations of complex topics, live and in real time. Host Meghna Chakrabarti leads provocative conversations that help make sense of the world with urgency, timeliness, and depth. Each episode is a deeply researched, beautifully produced hour. Listeners will learn, be challenged, and have some fun too.

• 0:41Mike Carruthers?

  In this episode, Meghna asks, could sunlight help treat disease? She details a growing number of studies that find potential benefits of UV light therapy for conditions like multiple sclerosis, type 1 diabetes, and Crohn's disease. Okay, so here's the preview, and you can hear episodes of On Point every weekday, wherever you get podcasts.

• 1:06Speaker 01

  WBUR Podcasts, Boston.

• 1:15Speaker 02

  This is On Point. I'm Meghna Chakrabarti. Imagine you're stepping outside on a bright and sunny day. What do you feel? Well, maybe the rays are warm and comforting on your skin. Maybe you tilt your head back, close your eyes, and see bright spots behind your eyelids. Maybe the sun is helping you feel happy and energized. Well, the sun's rays can have a profound effect on our bodies. According to a growing amount of research, sunlight kicks off an array of complex biological processes. It impacts our skin, of course, but it can also alter our nervous systems or our lymph and organs.

• 1:59Speaker 02

  It can slow down our immune response and lower blood pressure. But could sunlight actually help treat disease? Studies have found potential benefits of light therapy for conditions like multiple sclerosis, type 1 diabetes, and Crohn's disease. And so that's what we're looking at today. Harnessing the health secrets of the sun. And we're going to start today with Prue Hart. She's a professor at the Western, excuse me, the University of Western Australia, located at the Kids Research Institute in Perth. And her research focuses on the effects of ultraviolet radiation and vitamin D on the immune system. And she joins us from Perth, Australia. Professor Hart, welcome to On Point.

• 2:42Speaker 03

  Thank you. Very happy to speak to you all.

• 2:46Speaker 02

  Before we dive into the actual science of what sunlight does to the skin, it occurs to me that since I'm speaking to you and you're in Australia, one of the most sun-drenched places in the world. I mean, is that what got you interested in studying the effects of ultraviolet radiation? What's the story behind your, the thrust of your research?

• 3:07Speaker 03

  Look, I grew up in sunny country. We grew up thinking sun must be bad for you and bad for your skin. But I think we're all learning now that the harm benefits of the sun are really only at the skin level. The benefits of sun is really the whole body effects. And so I think we've got to consider harm versus benefit. And just in the last few years, that equation, the benefit is starting to outweigh the harm. Yes, you can get skin cancers. Our skin ages, obviously. You get a few more wrinkles.

• 3:52Speaker 03

  But hopefully, in this session, we'll develop more about the benefits, which really are so important for our human health.

• 4:03Speaker 02

  Hmm. So what are some of the benefits that research is starting to show of the effect of sunlight on the human body below the skin level?

• 4:14Speaker 03

  Well, I'm an immunologist, so I'm obviously interested in the autoimmune diseases or any diseases with an inflammatory component. And we know, in fact, most human diseases have an inflammatory component. We know that sunlight, particularly the UVB rays of sunlight, can dampen inflammation, whole body inflammation. We know that it also can reduce stress. We know that sunlight has another prong by stimulating adaption in the skin. So we learn to cope better with sunlight.

• 4:56Speaker 03

  We know of bone and muscular skeletal health. Well, that was known many decades ago with the advent of discovering vitamin D. But also our neuro system, our endocrine system, our metabolic system, even our eye system, our ocula system. We know myopia is related to children being outside and having more sunlight exposure. So really, the whole body benefits from sunlight exposure. So we've got to stop this exaggerated fear of skin cancers and think of some of the benefits and the positive aspects of sunlight.

• 5:41Speaker 02

  Hmm, hmm. I've been generically saying sunlight. Is that really what we're talking about? Or are we talking about UV and specifically UVB?

• 5:51Speaker 03

  Well, sunlight's very complex. UV is the highest energy component of sunlight. We know of the benefits from UV, but there are benefits of other aspects too. We know about blue light in our circadian rhythm. We know about infrared light at the other end of the visible spectrum. It can help in repair. It can help in heating the body. It's a whole package in a way, the benefits of sunlight. But we've evolved this way. We've evolved to get the benefits of sunlight. So. Not to take advantage of it, to to stay inside is not natural.

• 6:36Speaker 03

  We didn't evolve that way. We didn't lose pigment in our skin for a reason not to harness the benefits of sunlight. But UVB is the highest energy uh area of the of of sunlight. And that's the one we harvest in our treatment of of autoimmune diseases. Try and dampen those hyperactive conditions.

• 7:05Speaker 02

  Tell me a little bit more about what is happening as far as we know at the cellular level when we are exposed to sunlight. How does it actually dampen the immune response? Yeah, go ahead.

• 7:17Speaker 03

  Now, we know that the UV photons have a lot of energy. And we've got cells and molecules in the skin that can absorb that energy. And that energy then breaks molecules, changes molecules or chemicals in the skin. And then we get signals going uh from from the skin down to the lymph nodes and into our blood and into our circulation. We have a lot of immune cells and that's probably the greater network that's at play in our uh dampening of things like multiple sclerosis.

• 7:59Speaker 03

  But we also have the endocrine system in the skin. So the skin is really like causing bodywide communication. It's a very complex organ. But you can appreciate it's so important because it's it's our first line defense to to stresses, environmental stresses.

• 8:23Speaker 02

  Most people, when they think of ultraviolet and and the body, maybe if we've heard anything about it beyond the potential for skin cancer, people have heard, well, the skin's cancer is caused because the UV damages the DNA inside your skin cells. Um, so what is happening that's actually positive inside some of the cells or or whatever system you want to point to, um, that's actually changing it in a in a healthful way?

• 8:52Speaker 03

  But this is the whole point. If we reacted to every sort of DNA break in our skin, we wouldn't survive. We have inbuilt mechanisms, we have innate immunity, where the skin has adapted to be able to cope with the initiation of what might progress to a skin cancer. We don't react against it because otherwise we'd be responding to everything that comes and hits the skin. Remember bugs and viruses and scratches and all those insults of the skin. It's the same thing. We can't react to them all. We've

• 9:37Speaker 03

  got to dampen down our responses so we can evolve to be in survival mode. It's part of saying, look, the immune system, we don't want to respond. We don't want to be, you know, have a crash and burn response. We've really got to calm it down. And that's what we're harnessing then in treating autoimmunity. Because we know autoimmune diseases are when the body is reacting against self and it's usually via your immune cells. And in the case of multiple sclerosis, it's destroying the myelin sheath around nerves. So we've

• 10:21Speaker 03

  got to calm down those immune cells and say, hold on, stop it. So we, right at the skin level, we start developing regulatory mechanisms rather than reactive mechanisms. So if we can modify or, and that's, you know, it's all initiated or started first in the skin. And then, systemically, we're calming down where there's homeostasis needed. I mean, the whole, the body, go on.

• 10:56Speaker 02

  I was just gonna say, Professor Hart, if you could hang on for a minute. We just have to take a quick break and I'll let you continue when we come back. This is on point.

• 11:13Speaker 02

  Professor Hart, if I may, you're going to forgive me for asking a question repeatedly, but I really do want to know, kind of in more scientific detail, what we do know so far, what might be happening at the level of cells when skin is exposed to sunlight. For example, I'm reading here in the scientific press that says some researchers are tracking the way molecules in the skin such as uracatic acid or lumisterol affect immune system activity. Are these areas that you're studying and what are these chemicals?

• 11:45Speaker 03

  Yes, yes, yes. I mean, uracatic acid was first identified, oh, 40 years ago, as a molecule in the outer layers of the skin. And when it absorbs UVB photons, it isomerizes from a transform or a one molecular formal chemical form to another. And it's made more soluble by this transformation. And when it's more soluble, it can then go through the skin and to our circulation and is eventually measured in

• 12:23Speaker 03

  the urine. Now, it is a well-known immunosuppressant molecule. We believe it affects antigen-presenting cells, but many immune cells. So it's a molecule that has quite potentially a therapeutic benefit if it was given. The other one, lumisterol, is a product from vitamin D. Now, I think all your listeners will know about vitamin D. It is one of the molecules

• 13:01Speaker 03

  in skin. It's precursor. When it absorbs those UVB photons, that's 7D hydrocholesterol. When it absorbs the UVB photons, it converts to vitamin D and then goes to the kidneys and to the liver, where it's converted into the fully active molecule of vitamin D.

• 13:26Speaker 03

  Now, um, we know vitamin D that may be important. We do not believe it really is a very important molecule because trials of supplementation with vitamin D have suggested it is a small player relative to all the other molecules that may be made in the skin. And this is why it's a very exciting area of research. The skin, as I said, is so dynamic. It's so active. It's um, got so many pathways stimulating each other, feeding on each other to send signals to different parts of the body.

• 14:07Speaker 02

  Yeah, yeah. Well, Professor Hart, stand by for just a moment. Um, that's Prue Hart. You're listening to her from Perth, Australia. Let's go to basically the other side of planet Earth, to Edinburgh, Scotland, where Dr. Richard Weller joins us. He's a professor of medical dermatology at the University of Edinburgh. Dr. Weller, welcome to On Point.

• 14:28Speaker 04

  Um, hi. Great to be here.

• 14:31Speaker 02

  How sunny is it in Scotland today?

• 14:32Speaker 04

  Um, not, uh, not at all. Well, look, in Scottish terms, um, it's sunny. We've got a UV index of four. I mean, I, I, I used to work in Australia, actually, up in Queensland. So, so mid-winter, um, in, so mid-June, um, around the middle of the day in Queensland, where I was working, the UV index is seven. It rises to fourteen, um, in summer. Last year, here in Scotland, the UV index hit seven for five minutes on the 24th of June, if you're interested. And yet ridiculously, we copy sunlight advice from Australia. Completely irrelevant, and more than irrelevant, actually harmful. But we can discuss that.

• 15:17Speaker 02

  Yeah. Both of you are very keen to push back on the sort of accepted dermatological advice of protecting yourself from the sun. And I promise you, I will let both of you have your say about that a little bit later in the show. But as you can tell, I hope you can tell, I'm very keenly interested in trying to understand the mechanisms that are behind this, like, um... Suggestion that increased amounts of sunlight do amazing things for our overall health and not just for like our emotional well being. So Dr. Weller, I mean, you're in Edinburgh, it's a pretty high latitude city on planet Earth. I've been seeing that there is actually some correlation between disease incidence and literally like the

• 16:02Speaker 02

  latitude that you are at on the planet and vis a vis the amount of sun that you get. Is that true?

• 16:08Speaker 04

  Yes, it is. And look, the first thing, the first thing doctors should do when talking about, you know, why are we concerned about cigarettes? Well, because cigarettes shorten life. It's about four minutes per cigarette. Why are we wired about high blood pressure? Because high blood pressure shortens life. Why are we wired about poverty? Poverty shortens life. Well, what about sunlight? Well, actually, what the studies from up here in Northern Europe show, and this is studies from Sweden, and it's studies from here in the UK, they show that the more sunlight people get, the longer they live. Because, you know, this this equation, the bad side of sunlight, skin cancer, the good side, reductions

• 16:51Speaker 04

  in heart disease, cancer, which of those is more important? Well, actually, all cause mortality, death from any cause, is the mathematical, you know, it's the sum of those two things. And certainly in Northern Europe, the more sunlight people get, the longer they live. So if you are telling people to avoid sunlight, you really need to be saying why.

• 17:14Speaker 02

  Professor Hart, I mean, I wanted to hear you on this as well. So that people, just to be clear, there is a body of evidence that shows that people who live further from the equator, so therefore their exposure to sunlight is much more variable depending on season, that people living further from the equator tend to have a higher prevalence of some diseases. Is that true, Professor Hart?

• 17:38Speaker 03

  Yes, certainly in the autoimmune diseases. In fact, any disease with an inflammatory component. I talk about type one diabetes, Crohn's disease. So really, any disease with this inflammatory component that can be dampened by UV. Uh, there will be a latitude gradient. There'll be a seasonal effect. Uh, yes.

• 18:06Speaker 02

  Wow. And for this to actually have like scientific salience, it has to be on a, on basically on a population level, right? We're not talking about individual cases, right? We're talking about overall.

• 18:17Speaker 03

  Yes. Population level. Because we know that the environment by your genetics can combine to determine disease. But environment is a large component, and that's where the latitude gradient comes in.

• 18:36Speaker 02

  Okay. So Dr. Weller, Professor Hart earlier had talked about repeatedly autoimmune disorders and the impact that sunlight might have on the immune system. Um, cardiovascular health, can you tell me more about that?

• 18:49Speaker 04

  Yeah, so cardiovascular health, a big, big effect of sunlight. So if you're, if you're male in Scotland, but I think it also applies to females, you are 30% more likely to drop dead in a week in January than a week in July. So look, it's, it's August at the moment. I'm pretty mellow, you know, safe time of year. You know, I start to get a bit antsy towards the end of the year. This, this seasonal variation in disease is so built into us as the norm. You know, if you're a doctor, it is really busy in winter. And there's a kind of unspoken rule that you don't take holidays in winter because you're all really busy. And we know that blood pressure very much varies by latitude.

• 19:32Speaker 04

  So the further people live away from the equator, the higher average blood pressure is. And with that, we have higher rates of stroke and heart attacks. And then work that I've done, but colleagues in Germany have also done and reproduced, shows that sunlight releases this substance, nitric oxide from the skin. So when you're in the sun, NO is released from your skin. And what that does is it dilates blood vessels and lowers blood pressure. And that accounts for this huge seasonal and latitudinal variation in blood pressure and with it, heart disease.

• 20:12Speaker 02

  I was just gonna ask you, because heart disease is also one of those highly complex diseases where, you know, you have to talk about diet and things like that as well. But you're at least seeing this very strong correlation between nitrous oxide and and blood pressure, though. So that's that's significant.

• 20:28Speaker 04

  Yeah, look, so we've very clearly shown that shining UV at people releases NO from the from the skin and it dilates blood vessels. And then we've done big observational studies in America, actually looking at dialysis patients, because they get their blood pressure measured three times a week when they get dialysis. And we show that these 2,000 centers around America with different amounts of UV and temperature. And again, very clearly, we show that the more UV people are exposed to, the lower blood pressure is. But a really and and about half of this effect is due to temperature, but about a half is just due to UV.

• 21:12Speaker 04

  And another important thing in this is that black Americans get less of a fall in their blood pressure for a given rise in UV than white Americans. And of course, high blood pressure, strokes, heart attacks, heart attacks are particularly prevalent in black Americans compared to white Americans. And and skin color is all about handling sunlight. That's why, you know, pale skin developed as we moved away from Africa, where we all come from. And as people moved into low light environments, they developed pale skin just to soak up more of that sunlight that we need.

• 21:56Speaker 04

  And one of the things that it affects is blood pressure.

• 21:59Speaker 02

  Is it melanin specifically that we're talking about here? Because that's sort of the thing that provides the the visual cue of skin color. But does that have, is that is that part of the UV system you're talking about?

• 22:10Speaker 04

  Yeah, well, we don't know. All we know is that, so we know, looking at our African ancestors, that white skin within Africa, you know, before humans left Africa, we know that pale skin colors were actively selected against. You can see this in the genetic patterns. Of of skin pigmentation. But having moved to low light environments really quite recently in the last five to eight thousand years only, and we've been out of Africa for about sixty thousand years, there was then this really very strong selective pressure over the last eight thousand years for pale skin in northern Europe.

• 22:54Speaker 04

  And, you know, you you response to to sunlight is determined by skin color. So, you know, UV induced skin cancer is purely a disease of white skinned North European heritage people.

• 23:09Speaker 04

  And but at the same time, there is less of that healthy fall in blood pressure with darker skin types, less rise in vitamin D, which is a good biomarker for biological effects of sunlight. So, you know, skin color gives us an indication that there sunlight has to have benefits because repeatedly as people have moved to low light environments, pale skin has developed to try and make up for that lack of sunlight.

• 23:40Speaker 02

  Hmm, interesting. Professor Hart, did you want to add to that?

• 23:45Speaker 03

  You know, this observational study of as people live higher from the equator at at higher latitudes as populations, there are other studies that send the same message. I there's a lot of cohort studies that have been performed around the world. So cohort studies is where people study fifty thousand people or or that sort of number. And usually the healthier people are those with skin cancers. So that is telling us, yes, the skin is.

• 24:28Speaker 03

  Reacting and developing some skin cancers, some usually non-melanoma skin cancers. But they're healthier, their cardiovascular health is better. And that's also sending us a message that's just from natural observations.

• 24:45Speaker 02

  Yeah, you know, can I come back to something about vitamin D? Because I failed to understand completely what both of what you were saying. And actually, Dr. Weller, let me turn to you on this. People take a lot of vitamin D supplements. And as I think Professor Hart said earlier, that in and of itself may not actually be doing you any good. That it's vitamin D produced, what, out of the skin by exposure to sunlight? That's actually the beneficial one? Can you give me your take on that?

• 25:13Speaker 04

  Yeah, no, look, so sunlight hitting the skin makes vitamin D. So measured vitamin D in your blood tells you how much sunlight you've been exposed to. We know that people with high measured vitamin D in their blood are healthier in every way you can say, less heart disease, less cancer, less diabetes, less obese, live longer, et cetera, et cetera. The problem is when you give correlation is not causation is the classic saying. When you give people vitamin D supplements, and in America, you ran this huge study called the Vital Study, run out of Boston.

• 25:55Speaker 04

  25,000 Americans given, half of them given vitamin D for five years, half given a placebo. They didn't know which it was, all the results reported in the New England Journal. And basically, it came out vitamin D does pretty much nothing. There was some reduction in some autoimmune diseases, and that was it. Now, that is a huge study, and the results came back negative. So what this is telling us is it's not the vitamin D, it's something else. Vitamin D is a marker for sunlight exposure. And the problem with the debate for the last 100 years.

• 26:35Speaker 04

  Is that it's been dominated by dermatologists saying, oh, sunlight will cause skin cancer, terrible, and any benefits can be reproduced by taking vitamin D. And that's wrong. You know, vitamin D prevents rickets, but very clearly, I'm in a great editorial in the New England Journal about two years ago, 30% of Americans over the age of 60 take vitamin D supplements. And other than rickets and a few little fringe, you know, it doesn't do much. It's not the vitamin D, it's the sunlight.

• 27:10Speaker 02

  Dr. Richard Weller and Professor Prue Hart stand by for just a moment. When we come back, we will hear from a dermatologist who has a different view about exposure to sunlight. So we'll be back. This is On Point.

• 27:33Speaker 02

  Professor Hart, we had mentioned multiple sclerosis a couple of times here, and I just wanted to quickly ask you about some data that has been coming out over several years from Australia itself, because huge country, lots of different latitudes, so variable sunlight exposure within Australia itself, excellent medical record keeping. And I'm seeing here that there have been several studies that show a correlation between the incidence of multiple sclerosis and the latitude at which various Australians live. It's a fairly strong correlation. That feels quite remarkable to me, Professor Hart.

• 28:10Speaker 03

  I think this is wonderful data. It shows quite clearly that in the southern parts of Australia, such as Hobart, there is five to sevenfold greater prevalence of multiple sclerosis than up in North Queensland near the tropics. So I think this is really, it's happened naturally. It's showing us. That it's it's it's a real thing that the UV exposure, sunlight exposure can actually dampen the initiation, the progression, the development of multiple sclerosis.

• 28:52Speaker 03

  Such that if you get exposure to less UV down in the southern parts of Australia, you have more disease.

• 29:01Speaker 02

  Hmm.

• 29:02Speaker 03

  And we've taken this a step further.

• 29:04Speaker 02

  Oh, I was just gonna, I was just gonna ask you about that because my first question that came up when I was reading about these sort of population wide studies in Australia was correlation doesn't equal causation. There may be other things going on at different latitudes in Australia. But you did follow up research in a more, much more controlled manner. Can you tell me about that?

• 29:21Speaker 03

  We, we've done a study giving narrow band UVB to patients with the earliest form of MS. Now, this was important because we know dermatologists give narrow band UVB to treat skin conditions. We were trying to give it to patients with such that it had internal benefits. And it was not difficult to get through ethics committees because it's so safe to give narrow band UVB. It's wavelengths of, of UVB that have had no effect on skin cancer induction at all.

• 30:02Speaker 03

  So we did a study of twenty patients, ten got the narrow band UVB, ten did not.

• 30:10Speaker 02

  With a light box, yeah.

• 30:12Speaker 03

  With a light box, three times a week, uh, for eight weeks. And we followed the patients for a year. After twelve months, all of those who got the placebo light, developed multiple sclerosis. Those who were given narrow band. Only seventy percent developed multiple sclerosis within twelve months. So this was a huge effect. Thirty percent reduction in the conversion from the very earliest forms of multiple sclerosis to full blown disease.

• 30:54Speaker 03

  And this is what we need to work on further. We need to be able to show this clinically more definitively. The wonderful thing is, we then had a bio bank of cells and blood from these participants. And we've been able to find a little bit of mechanism by which UVB might be working.

• 31:16Speaker 02

  Yeah.

• 31:17Speaker 03

  Particularly through the blood. And and also the participants loved the treatment. They loved it. They felt something was being done for them. They can now being shown that the the light boxes can be given at home. So really, we think we are advancing in being able to use a component of sunlight to dampen autoimmune disease like multiple sclerosis.

• 31:48Speaker 02

  And to be clear, these light boxes are not like tanning beds, right? They're different.

• 31:54Speaker 03

  No, no, no, they're they're narrow band UVB. The dermatologists have been using them for decades. And as I said, they're now so safe. The health funds in the US, Kaiser Permanente, is supporting them for use at home. Not in in a clinic, but at home.

• 32:18Speaker 02

  Yeah. Okay, Professor Hart and Dr. Weller. By this point in the show, I know that many dermatologists, especially in the United States, are probably. Ready to scream at me because of their profound concerns about excessive sunlight exposure on the skin. So to that point, we did speak with Dr. Vina Van Shinathan. She's a board certified dermatologist who practices in the San Francisco Bay area, and she's a member of the American Academy of Dermatology.

• 32:46Speaker 05

  My opinion as a dermatologist is that minimizing sun exposure as much as possible is ideal. Bring your sunscreen with you as much as you can. Bring your hat with you, and that will go a really long way at preventing you from developing skin cancer or those signs of premature skin aging.

• 33:05Speaker 02

  Van Shinathan says that, yes, the sun feels good, and it's impossible to avoid sunshine completely. But she says, in her opinion, those small amounts of exposure over time really do add up.

• 33:18Speaker 05

  So five minutes walking your dog, or 10 minutes walking to your mailbox, driving without wearing sunscreen, adding in a couple beach days. In general, for most Americans, harmful sun exposure isn't really coming from the Fourth of July or that day at the beach. It's really coming from the day-to-day cumulative effects of ignoring those five minutes.

• 33:45Speaker 02

  And Dr. Van Shinathan says exposure to UVA and UVB rays from the sun can cause fine lines, wrinkles, and brown spots on the skin. And of course, the big concern is it can also cause skin cancer.

• 34:01Speaker 05

  Data in the United States shows that approximately one in five Americans will actually develop skin cancer at some point in their lifetime. Most commonly, a type of skin cancer called non-melanoma skin cancer. Those encompass two large buckets called basal cell carcinoma and squamous cell carcinoma. Those are the two most common that we're going to see that can be quite directly linked to sun exposure and our sun protection habits.

• 34:34Speaker 02

  And for melanoma, it is true that rates of melanoma have been rising rapidly over the past 30 years in the United States, according to the American Academy of Dermatology. The AAD estimates some 212,000 new cases of melanoma will be diagnosed in 2025 alone. Van Shinathan also says the sun is strongest between 10 a.m. and 2 p.m., so it's best to limit your exposure during those hours, according to her. You can check to make sure the UV index is below three or four before heading outside, she says.

• 35:10Speaker 05

  It's hard to find such a clear-cut paradigm, if you will, for other cancers, where do this and this won't happen, and don't do that, and, you know, this cancer will develop. But we do see that with skin cancer. It's very clear that avoiding the sun and wearing sunscreen can go such a long way at preventing someone from having a really, really awful experience with something like melanoma or skin cancer.

• 35:36Speaker 02

  That's Dr. Vina Van Shinathan. She's a board-certified dermatologist in the San Francisco Bay area. Okay, Dr. Weller, go ahead.

• 35:47Speaker 04

  Okay, would love to. So basal cell skin cancer is common, common than every other cancer put together. When you have a basal cell skin cancer diagnosed, your life expectancy goes up. I don't see that as a problem. Melanoma rates have increased sixfold in the United States in the last four years. That's diagnoses. Deaths have not changed. A Day Adamson, fantastic dermatologist in Austin, Texas, look up his stuff, published in JAMA and the New England Journal. So in America, your biggest risk factor, so looking at diagnoses of melanoma and how sunny it is where people live, great paper in JAMA Dermatology, pretty much no relationship.

• 36:30Speaker 04

  The biggest correlation between a diagnosis of melanoma is how rich you are. So the richer counties are, the more likely people are to be diagnosed with melanoma.

• 36:44Speaker 04

  The more biopsies are done, the more likely

• 36:47Speaker 02

  It's because they have better healthcare. I'm just gonna jump in here and say my supposition. Is that in the United States? Yeah.

• 36:54Speaker 04

  That's the argument. There's no change. So, look, if all of that healthcare was really effective, you would expect a fall in deaths from melanoma. There has been no change up or down, no significant change up or down in deaths from melanoma in the last 40 years, despite the huge rise in incidence.

• 37:15Speaker 02

  But Dr. Well, let me jump in. Can I just?

• 37:18Speaker 04

  Yeah, yeah. Come in with the counter argument.

• 37:20Speaker 02

  Yeah, yeah. Well, not necessarily a counter argument, but just to make this a little more complex. Death is not the only negative outcome from having, from melanoma, right? I mean, like, so just that the change in the death rate is not a good enough reason to say, well, the increased diagnoses have not been effective.

• 37:41Speaker 04

  I think not being dead is the most important endpoint. I'm kind of agnostic about what I don't die of, whether I don't die of being struck by lightning, don't die of skin cancer, don't die of heart disease. I really don't care. I just don't want to be dead. And I am interested in factors, exposures, that reduce my risk of death. And certainly here in Northern Europe, the more sunlight I get, very markedly, the lower my risks of dying. So we are about to publish a paper. We had one last year, another one out here. And in the UK Biobank, this huge, great, forward-looking study of half a million people in Britain,

• 38:25Speaker 04

  which has got very good data on how much sunlight exposure people got, and also education, income, smoking, exercise, et cetera, et cetera.

• 38:35Speaker 04

  We find that if you reduce sun exposure for a British cohort enough to reduce one death from skin cancer, that associates with 50 extra deaths from other causes. Now, now, look, that may not apply directly in America because you're a lot further south than us, but the risk benefit ratio is enormously in favor of sunlight exposure in Northern Europe. And I suspect to a lesser degree that will apply in America. And all dermatologists think about is the skin, and that's not good medicine.

• 39:14Speaker 02

  Professor Hart, let me turn back to you because we've only got about three-ish minutes here remaining in the conversation. And what I think about more often, I mean, melanoma is an important issue, I'm not going to diminish that, but we're not talking about having to go outside for 12 straight hours a day and have the sun beat down on your skin. It sounds like from this conversation that even small increases or moderate increases in sun exposure can provide some significant health benefits. And so since you're at the Kids Research Institute in Perth, it suddenly occurred to me, I don't know if this is happening in Australia, but in the United States, there's been a growing issue over many years that kids during the school year especially barely

• 39:57Speaker 02

  go outside at all because the amount of recess that they're having is has been, you know, reduced. Are we seeing impacts on children's health from reduced sun exposure?

• 40:07Speaker 03

  You are so correct in that. Yes, the clearer studies are with myopia and eyes for children, but yes, with type one diabetes, that's a children's disease. In fact, we know a lot of autoimmune diseases start in childhood, may even start in utero. And yes, sun exposure is so important there. And I think Richard brought it up, it's the risk to benefit ratio. And I think dermatologists, the American dermatologists, all they think about is risk. We've really got to move that pendulum a bit more to considering the benefit.

• 40:54Speaker 03

  So a little bit more sun exposure, we say never get sunburnt. Cause sunburnt is the initiating event for melanoma. We just say never get sunburnt, but certainly get sun exposure. Because that is going to be homeostatic and so good for you for health.

• 41:15Speaker 02

  This is really key. Get more sun exposure, don't get burned. Okay, I have a question for you, though. I mean, like depending on, maybe this is highly variable depending on each individual. But how can we measure what it at? Like what that threshold is between a healthy amount of sunlight and I might be outside long enough to get burned.

• 41:37Speaker 03

  I would say just never get sunburnt. Everyone, you have to consider your own intelligence. You know, when you're going to get sunburnt. And I think just make sure you get out a little bit every day and and get a little bit more than you might have been getting up till now. You'll feel better. Your energy levels will improve. Your whole body health will improve. But never get sunburnt.

• 42:14Speaker 02

  It's so funny, maybe I'm just not that sun intelligent myself. But when I'm outside for a long time, I do wear some sunscreen. But when I don't reapply it, sometimes I don't realize that I'm getting close to being burned until well after the fact. Maybe that's because I've got brown skin, who knows? But Prue Hart, professor at the University of Western Australia, located at the Kids Research Institute in Perth, Australia. Thank you so much for joining us today. And Dr. Richard Weller, yeah, Dr. Richard Weller, professor of medical dermatology at the University of Edinburgh in Scotland. Dr. Weller, thank you so much for being with us.

• 42:50Speaker 04

  Thank you.

• 42:51Speaker 02

  I'm Meghna Chakrabarti. This is On Point.