Dr Rupy: Welcome to the Doctor's Kitchen podcast. The show about food, lifestyle, medicine and how to improve your health today. I'm Dr Rupy, your host. I'm a medical doctor, I study nutrition and I'm a firm believer in the power of food and lifestyle as medicine. Join me and my expert guests while we discuss the multiple determinants of what allows you to lead your best life.
Dr Rupy: Hey, it's just Rupy here today. I'm going to be taking over the podcast and talking to you guys about everything to do with skin food and skin in general, actually. We're going to do a bit of a refresher. And this is the start of a number of different episodes that I want to do solo to go over some of the studies that we used to create recipes for the six health goals that you'll find on the Doctor's Kitchen app. You'll find the link to the app at the top of the show notes of this episode, wherever you're listening. And over the next couple of months, we're going to be talking about each individual health goal, skin health, mental health, brain health, inflammation, heart health and general wellbeing. And I want to give you a behind the scenes look at how we created our simple but smart algorithm. It's going to be a bit of a refresher as well for some of you who are avid listeners of the Doctor's Kitchen podcast, because we've talked about these individual subjects in the past, but I think this series of episodes is going to be a lovely way to tie everything together. And so, let's start off with the skin. So today's deep dive is going to be all to do with the skin. And forgive me if the initial part of this pod is a bit too basic, but I think even for people who know what I'm talking about, I think it's important to get the fundamentals right, to give you an understanding of the organ that we're talking about and then bring in the nutritional medicine and lifestyle component. So let's dive into everything skin related. I'll give you a summary of what we're going to be chatting about. And I'd love your comments on these as well because you don't have to download the app to benefit from this episode. That's not what this is about. It's giving you a behind the scenes look at why this is very different to any other apps that you'll find out there and how you can use this information to make recipes yourself with skin in mind and also how it's very, very much tied to all the other health goals as well. So we're going to go back to the fundamentals and talk about what the skin is, why healthy skin matters for everyone, not just people who have common skin problems, and what happens when skin dysfunction occurs and what the what the drivers behind that might be. Hopefully, after listening to the pod, you'll have a better understanding of how what we eat affects the skin and the connection between the gut and skin health. We've talked about that on previous episodes briefly as well, and I want to give you a bit of an idea about the potential mechanisms behind the gut skin axis. This should be reinforcing two previous episodes on skin health and suggestions in other episodes as well, namely the episodes on eczema and another one where we talked about collagen, acne and supplements. We're not talking specifically about collagen in this episode because I think that probably requires its own episode itself, but we did talk at length about collagen in a previous episode if you are interested in specific supplements like that as well. We're going to be diving into some of the research papers looking at dietary patterns linked to skin health, so what pattern of eating, specific nutrients linked to the skin, whole foods and what limits nutritional research because I think it's very important to be transparent about the limitations of how much we can draw from the available research that we have access to. And this is essentially the the skeleton, the building blocks of how we created our algorithm in the first place and how we refine what recipes you see on the app according to everything we're talking about today. Hopefully, you'll you'll get some practical tips to easily translate this knowledge into everyday life. And like I said, we're going to be talking about how we use this information to create recipes in the app, but also after listening to this, I hope you're reassured that the recipes on the app are using this evidence-based eating principle approach, as well as some ingredients that you can think of yourselves to create flavourful and practical recipes if you if you like that exercise of creating recipes yourself. So, yeah, hopefully and hopefully we're going to be bringing a bit more of this rich content to the app as well. So at the moment, everything is sort of hidden behind the recipes and the filters, but we are working on ways to create short, bite-sized bits of content. So you don't have to listen to me for an hour or however long this podcast is going to be, explaining all the nuance to everything. They're going to be short, sharp, almost like quick cards that you can refer to and like, ah, that's what I can put in my shopping basket or this is how I can try and get more of these categories of ingredients into my into my diet. We're also doing a new thing on the podcast, which is our podcast recipe of the week, a recipe that reflects the topic of conversation on the podcast from the app. This week's, which is going to be reflecting skin health, is the courgette korma. It's got a wonderful mix of base flavours in onion, garlic and ginger. We've got wonderful spices like turmeric and cinnamon stick in there as well and garam masala. And it's got a base of almonds, plus it's got some yogurt in there. You can use a non-dairy yogurt as well, one that has probiotics preferentially added to it. But that kind of brings in together so many different elements of what we're talking about and hopefully that will make sense at the end of this podcast as well. It's got a whole bunch of greens in there too. So that is the courgette korma. You can find that on the Doctor's Kitchen app and you'll find it on the newsletter as well if you're a subscriber for free too. And I should say that all the links to the newsletter and the website and the recipe that'll be on the newsletter for free and all the rest of it, all the links for that are in the bottom of the podcast show notes description. So you'll find all the links there. Okay, fine. Let's let's dive in into this first episode looking at why our health filter function can tailor choices according to your needs and reduces that stress of having to decide what to eat using Google and then how to make all the recipes using the healthy ingredients that are being suggested to you as well as, you know, why this is an evidence-based approach. Before we start, I do want to give a shout out to the research team for helping me compile all this information. It would not have been possible without the network of collaborators that we have at the Doctor's Kitchen. And of course, the scientists around the world who have conducted the primary research that we've used to further our collective knowledge. I think it's a really important shout out because without any of this, it's just, you know, us trying to figure things out and luckily we have access to a wide range of information as well and then people who are pushing the subject of nutritional medicine forward. All right, so let's start off. What is skin? What is skin? One of the largest or largest, the largest organ of our body. The surface area of about two metres and a mass equal to around 15% of your total body mass. It's made of two main layers, your epidermis, the upper layer, which is responsible for many of the barrier functions of skin. There's a number of different cells that make up the epidermis. They're largely made up of keratinocytes. And the dermis, which is underneath and there's there's a structural and nutritive component of the dermis and they have essentially like your backup support underneath the epidermis. They house blood vessels, nerve endings, hair follicles and glands. And they make up the skin, which is exceptionally essential for the normal functioning of our body. It protects our bodies from external stresses, they regulate body temperature, it holds fluids in, of course. And your skin is constantly exposed to a variety of external stresses, environmental stresses, infections, heat, cold, chemical irritants, things like car emissions, household cleaners, radiation and other compounds. It's, you know, your your skin has to be particularly resilient. So in the absence of a condition, it's exceptionally important to make sure that you are eating according to what your skin needs are as well. We're very good at that. Essentially, the whole concept of eating for or a health goal is to maintain this concept of homeostasis, which is balance and consistency necessary for good functioning and health. I've already alluded to this. So the the second question is really, all right, why is healthy skin important for everyone? It's not just important for people with skin conditions, it's essential for general health to essentially perform all those different functions that we've been talking about. Protection from external triggers such as microorganisms and radiation, I think is a subject that's going to get a lot more attention because we are increasingly exposed to a, I hasten to use the word, but a toxic world. Now, I know the more we find out about what the potential harms are in our environment, it can trigger anxiety and health anxiety. Before we we go into more nuance discussion, I just want to remind people about just how resilient your bodies are. We are exceptional detoxifying machines with an amazingly resilient body, internal ecosystem, external ecosystem. We don't have to worry about these things too much. However, having an idea of how your organs work and what needs they have and how we can better support that, I think is important as well. So just bear that in mind. It's not that you if you don't eat according to this way, then your skin's going to fall off. It's nothing, you know, as drastic as that. The other important functions for skin apart from barrier function and protection is regulating water content, insulation, through things like controlling body temperature through things like sweating and diversion of your blood vessels away and to your skin as well, again, for the purposes of heat regulation. Vitamin D production, very, very important. And also not to forget the psychological effect as well. Skin appearance is what we present to the world. So having a skin that is as healthy as possible, I think in society is it's it's important and I think it's important for a lot of people as well. Good. All right. So let's let's go into what damages the skin. So we just we mentioned solar ultraviolet radiation. It comes from the sun, penetrates our skin cells. It's absorbed by different cells. And essentially what radiation does is promote oxidation reactions. It generates reactive oxygen species, something that you're going to hear about a lot more during this episode as well. It occurs in moderate amounts because we have our own antioxidant systems in the skin to combat the the reactive oxygen species that are produced and repair the damage to proteins that it can cause as well. In excessive amounts, this can overwhelm these defenses and lead to permanent damage or photo damage. And that's what you can see from years and years of exposure to too much light or not or being in an area around the around the world that doesn't have as much protection via the atmosphere due to holes in the ozone layer, etc. And that can lead to premature aging of the skin. So if you get this idea of like a seesaw in your head, on one side, you have your defense systems, on the other side, you have those piling on damages from reactive oxygen species. And you actually want to get balance. You don't want to remove everything in terms of the reactive oxygen species because those actually create cell signaling and cellular adaptive responses. I.e. a little bit of damage does you some good because it keeps you a bit more resilient. This concept of hormesis. But if you have too much, it can overwhelm it and that's what can lead to dysfunction of your skin as well. Other obvious things that will damage the skin, things like pollutants, skin injuries and other chemicals as well. All right, so what happens? What okay, what actually happens when the skin is damaged or doesn't function properly? I've just explained how you have that that seesaw, you have excess damage. What what what happens at, you know, that that the the level and what kind of things does it associate itself with in terms of what are the conditions? So, dry skin. Dry skin is more susceptible to skin diseases and prone to things like redness, itchiness and flakiness and irritation. When you when you do have damaged skin for whatever reason, it can alter the skin permeability as well. This can also lead to skin laxity and wrinkles. And this is where everyone's ears tend to prick up. Whenever I talk about wrinkles in presentations and all that kind of stuff, everyone always asks me about it. So skin laxity and wrinkles is where the skin loses its firmness and structure and becomes loose and starts to drop. And it's caused by poor support of the epidermis and the underlying dermis, lower collagen levels. That's that's quite well recognised, which is why there is a pervasive sort of belief that if you ingest collagen, then it can improve your collagen levels. Again, the mechanisms behind that are a bit shaky and I think we have to learn a bit more about whether that's true or not. Reduced vascularization, which reduces the nutrient uptake to the skin. So all the and all these different mechanisms coalesce to to create issues with with the skin itself. Nutrition and nutritional factors are thought to help beyond promoting collagen production, antioxidant activity, which is something that we can increase with what we ingest, are thought to improve skin aging, maybe not reverse skin aging, but certainly improve its degradation. So, yeah, we'll talk a bit about the mechanisms a bit later. And the other things that can happen when skin is damaged or doesn't function properly are things like acne and dermatitis, which is a dry, irritated and inflamed skin as well. And there may be links with the gut with that as well. So, we'll talk a bit about the innate skin protection mechanisms because I think this is this is probably most important as it pertains to the first bit of this podcast because rather than relying on external ingredients, i.e. your your diet and what you can put on the skin to improve skin, your skin looks after itself in many different ways. So they they your skin cells keep reactive oxygen species, a product of normal metabolism as well as exposure to harmful radiation. They keep it within a normal range by employing antioxidant molecules. And you already have intrinsic antioxidant processes to to to balance this. But when the excess of these molecules overwhelms the the defense systems, that's where you get dysfunction. The skin cells repair those minor injuries that occur every day because of exposures to our exposome, if you like. Our exposome is basically the collection of all the different things that we're exposed to via chemicals, environmental pollutants, radiation and more, by actually secreting pro-inflammatory chemicals. So pro-inflammatory chemicals from your immune system. What that does is that it signals the alarm, it recruits immune cells to the area, which is how you actually get repair. So it sounds a bit counterintuitive that you've got injured skin and you're secreting molecules that actually would create an excess of inflammation further, but actually that mechanism leads to more recruitment of the immune cells, which is actually how you repair injuries as well. And the way the inflammatory response is overly activated is because you have things like persistence of these pro-inflammatory chemicals, also called cytokines. You get dysregulation of the proteins because they they they can disrupt proteins in your cells. And then that leads to chronic inflammation. So it's not inflammation per se, it's the imbalance and the persistence of inflammation that can lead to various skin diseases too. So hopefully all those different mechanisms that I've described give you an idea of what is important for skin health. And in a word, it's balance. It's balance between all those different mechanisms. It's balance between your immune cell activation. It's making sure that you're not damaged too much. And we're going to talk about why diet can help with that as well. So I I would argue food is one of the modifiable factors that we all have access to when it comes to protecting our skin. One of the most effective modifiable factors, I should say. So if you think about food, let's think about it according to two different streams. So when you consume food, it's digested and absorbed into the bloodstream. And that's how it acts on various cells and tissues in our body. The other way is if it's undigested and it passes on through the gut and feeds the community of bacteria, or I shouldn't say bacteria, it's microbes, but let's say for for this sake, it's the bacteria that reside mostly in the large intestine. So if you think about those two sort of pathways, we can split it off in our mind and we can talk about both of them in turn. How these food components affect the skin. The nutrients from our diet can act on various mechanisms to protect the skin and ensure it repairs to counter damages and promote skin health, reducing skin disease. So let's look at those two different pathways in turn. We're going to start off with the gut. It's, you know, it's the root of a lot of why food can have such a drastic impact on health in general, as well as the other mechanisms. But we're going to start off by looking at the gut. The main way is by balancing your gut micro population. How and what we eat shapes the composition of this collection of microbes in the gut. And collectively, this this sort of mechanism is is described as the gut skin axis. So let's let's do a bit of a refresher of one particular attribute of food, which is fibre. Fibre is a type of complex carbohydrate. So yes, it is a carbohydrate. I know carbs in general have been demonized and I think the way we talk about carbs probably needs to change because that's why you might notice me always saying it's the excess of refined carbohydrates or sugar. And although those are all carbohydrates, not all carbohydrates are the same. So fibre is a type of complex carbohydrate that you find in whole grains, beans, nuts, legumes, fruits, vegetables. It's not digested and we used to think of it as just roughage and material to almost like push things through. I remember actually being in med school when I was thinking about roughage in that way and they had like a an image of a, I think it was chicory or asparagus or something like that. And I just thought of it as like a tractor that just pushes things through your immensely long digestive tract. But it's not that at all. We've we've had really warped thinking about roughage in general. Roughage, I don't use that word anymore. Instead, what happens is that it's fermented by microbes in the large intestine and this is turned or metabolized into products that balance the gut environment, including most well known, the short chain fatty acids, things like butyrate, propionate and acetate. Those are the three main ones. And those have various roles in the in the colon. They nourish your colonic cells, they're involved in your immune system, energy for your cells. We'll get onto that in a sec. So our diet is an important contributor to the composition of the gut microbiome. And there is a theory called the diet microbiome theory or hypothesis that suggests that the increased prevalence of allergic disease, we talked about this on the allergy podcast, but the increased prevalence of allergy, including skin conditions, is in part caused by low fibre and high fat concentration of our diet, characteristic of the Western diet, which ultimately leads to changing the gut microbiota to one of one that is imbalanced. So there's less diversity in the number of different types of microbes you have. And the fancy word for this is dysbiosis, which is another way of describing an imbalance and it also refers to potentially a higher proportion of what is colloquially known as bad bacteria, but I don't think it's particularly accurate because sometimes the quote unquote bad bacteria is actually doing some good. But let's just say there's there's a more pathogenic bacteria, so things that are disease causing. And that leads to a deficiency in the production of your immune cells that are creating balance, a reduction in the short chain fatty acids that have important roles in the gut. There's also evidence to show that the ratio of specific microbes, mostly firmicutes and bacteroides, can lead to this impairment of the maintenance of your gut cell function, which can lead to intestinal permeability or hyper permeability, also colloquially known as leaky gut. And then you have your impaired gut function. So that's the a very basic cascade of what can happen if you don't have a healthy diet to support normal gut health. The good thing about that, I know I've just painted a picture which is pretty dire of people who might have low fibre diets or who have eaten a certain way that might be classed as a westernized type of diet for a long period of time. Your gut is really responsive. So the microbiota in the human gut can respond rapidly to changes in the diet. And these, you know, the populations of your of the population of microbes can double within an hour and the gut can purge the community or does purge the community every 24-48 hours. So that should give you an idea of just how effective dietary change can be and how rapidly effective it can be as well. And this is supported from evidence from from people who switch diets. I don't recommend making drastic changes over such short periods of time. I think it's much more sustainable to to make these changes over weeks and weeks rather than hours or or days because the shift in composition can be really noticeable as well. But that I think that just as an aside, I think that shows just the power and the rapidity at which we can create change using dietary interventions. And over the long term, dietary habits are a dominant force in determining the composition of an individual's microbiota. Early life also has a role in gut health, but, you know, we'll save that for another pod. And I don't think it's as attributable to today's podcast. Unless, you know, you have children who might have eczema, there are ways in which to introduce a variety into one's diet, obviously under the suggestion of your doctor and your physician and even nutritionist if you're lucky to have one, with the with the objection with the aim of of improving skin conditions if they have an allergic component. I think those are quite effective. So let's talk about how your gut microbiome, your gut environment, your gut microbiota affects the skin. So the connections, so if you think about this diagram, we've gone down the the gut route, we're leaving the the chemicals in our bloodstream for a little bit later. And then within the gut route, you have direct and indirect route to the skin. And as mentioned and as referred to as the as the skin gut axis. Well, actually, it can be there's there's a a more popular term that's going around the rounds at the moment. It's the microbiota gut skin axis. So actually, it's more about, okay, how do you eat to impact your microbes? How do your microbes interact with the gut? How does your gut interact with your skin? And that's the axis that we're talking about. But I mean, it's all like semantics really, because you could call it the microbiota gut bloodstream skin axis because that, you know, obviously has to go through the bloodstream before. But anyway, it doesn't matter. There's numerous studies that link the your your digestive system to skin functioning. Indirect route is by modulating our favorite word, inflammation. Inflammation, if you've read my second book, you'll you'll know that it's it's very misunderstood, I think as a term. I've actually done a podcast all about inflammation with a colleague of mine who's an immunologist. So if you want a refresher about how to conceptualize inflammation, I highly recommend you go and listen to that podcast, eating for inflammation. But inflammation in itself is when we talk about inflammation, we're talking about it at a cellular level and also in the gut ecosystem as well. Microbes influence the integrity of your intestinal barrier. So, like we said, your microbes metabolize this ingested food, it goes into essential compounds like short chain fatty acids. And then when we refer to this intestinal barrier, what we're referring to is the connection between your gut epithelial skill cells, also known as tight junctions. So, if you think about going into a microscope, you're in your gut and you look at the wall of the gut and you you zoom in, zoom in, zoom in until you get to the the the smallest area that is between the inside of your gut and then you have your the cells and then you have your bloodstream. It's one cell thick. It's it's a very, very small connection. And the reason why is because you're absorbing so much from your gut. And these the spaces in between these cells, if your gut lining is a cell thick, the spaces in between them are called tight junctions. And they have to function appropriately so that they can absorb what should be going into the bloodstream and not absorb what shouldn't be going into the bloodstream. And the way these work is, well actually, before we talk about that, I just want to say that it is referred to as leaky gut and intestinal hyperpermeability when there is too much of a gap or the gap is prolonged. But you do need to understand that it is normal for the gut to absorb nutrients via these channels. But the loss of balance between absorbing and not absorbing enough or absorbing too much can influence whether the contents in your gut can absorb toxins and inappropriate bacteria from the gut into the bloodstream. And what happens when that when that occurs is an excessive trigger to your immune response, which causes systemic inflammation. So, if if I just reverse gear for a second, so you have products in your gut and you have products in your bloodstream. What what determines what goes into the bloodstream are your epithelial cells, your intestinal barrier. In between your cells, you have those tight junctions. Everything works in harmony when there's an appropriate system of communication and there's an appropriate amount of what should be going into the bloodstream from the gut via these channels. Too much of acceptance, if you like, of all those different products that should be in the gut going to the bloodstream can trigger inflammation. And that's essentially how your your gut modulates inflammation. And if there is too much, you get an immune activity, that immune systemic inflammation can travel, obviously around the bloodstream. If you think about anything goes into the bloodstream, it's a hyper connection that connects with every element of your body, which is why you can get some very, very vague symptoms that are associated with gut dysfunction. And the I mean, the the the the best connection we have with the outside world is via our gut as well, which is why a lot of people are now coming around to the idea of the gut being a central part of where we should be focusing our efforts when it comes to diagnosing issues that might, you know, you wouldn't, you know, necessarily think of as having a role with the gut. It's funny because within Ayurvedic practice and I believe other traditional forms of medicine, there's been a focus on the gut for millennia. And we're just coming around to this idea with, you know, modern science and using modern techniques that, you know, yeah, they've been pretty right all along. So, it's it's interesting looking at this through the lens of what the current research says, but also through the lens of what my ancestors and what my family tell me. So, yeah, that that's a just a an aside. That's described as the indirect route. This is basically how gut cells cause or the the gut can modulate inflammation. Although in my mind it's, you know, you can understand how it can be a relatively direct route as well. But anyway, that's the indirect route. The more direct route is really interesting. So there is a suggestion that gut bacteria and their metabolites can gain direct access to the skin. So, gut bacteria and their metabolites, i.e. the substances that they produce as a product of fermentation, may enter the bloodstream and potentially travel to the skin, accumulate in the skin, impair epidermal differentiation. So that's basically how the dermal, the epidermal layer can create different types of cells with different functions and directly impact their skin barrier integrity and disrupt the beautiful homeostasis of your skin cells. This when I found first found out about this, it's kind of blew my mind, the fact that you can have bacteria traveling around the the bloodstream and actually directly impacting skin cells. So there is a bit of evidence for this. It's still sort of, um, if you like a theory, but there is some there is some evidence. So molecules produced by the bacteria, these metabolites can access the circulation and affect distant sites. One of which is just is the skin. There there is evidence for potentially these metabolites impacting different areas as well. So to understand this, I think it's important to just revisit the metabolites of gut bacterial fermentation. So we talked about short chain fatty acids. There there are some metabolites produced by the gut bacteria that are thought to have negative effects as well. They're regarded as bioactive toxins. And a couple of these, as described in this paper, are called phenol and p-cresol. These are metabolites of aromatic amino acids produced by gut bacteria. So they're thought to indicate a disturbed gut environment and you can measure these these as biomarkers in the serum. There is some evidence in vitro, so that's where you look at cells in the lab, that they accumulate in skin cells and they reduce the expression of certain building blocks of skin, which is shown to disturb, you know, that that lovely balance of skin cell turnover, which is where skin cells die and they're removed and they're replaced quite quite quickly and nicely. So they they can disturb that sort of process of balancing skin and obviously its normal protective normal protective functions. There's animal evidence that the phenols, so these bioactive toxins produced by gut bacteria can accumulate in the skin via the circulation and again, disrupt these skin cells in their in their normal mechanisms of of self-protection and self-renewal. There's also human evidence which found that elevated levels of these metabolites that are thought to be negative and associated with a disturbed gut were associated with reduced skin hydration and reduced size of some of the skin cells as well. So there there is some evidence and there's a whole bunch more studies that I think are quite nuanced, so we have to take this with a pinch of salt, but there is some evidence to suggest that if you have a disturbed gut bacterial population as a result of, let's say diet, but also it could there could be other mechanisms. But let's just say you have a disturbed gut, it produces bioactive metabolites, that can go into your bloodstream and that can have a direct impact on the health of your skin cells. So that is one of the the issues, potential issues. The other issue, again, within the bucket of direct mechanisms by which the gut can impact the skin is the bacteria themselves that can actually access the bloodstream and affect the skin. This this for me was was like, yeah, quite groundbreaking. So there was a recent study that was published in JAMA Dermatology. So JAMA being one of those high tier papers, in 2015, that found that the DNA of bacterial intestinal origin, so you've got DNA from bacteria that reside in the gut were found in the blood of patients with psoriasis. So you've got the DNA, a marker of bacteria that usually resides in the gut found in the blood of patients with psoriasis, which is a relatively common skin condition that's characterized by plaques on the skin, very itchy, and it's it's something that we we do struggle to treat in a lot of cases and it's thought to have an autoimmune origin. And what these researchers did in this particular paper that I'm referring to, the links of which will be we're going to put all these on the website by the way, and all the articles and stuff. But they collected blood samples from 54 patients with psoriasis and 27 controls. So relatively small. And they analyzed the samples for these inflammatory chemicals such as interleukins, as well as bacterial DNA. And they found that bacterial DNA was present in a third of patients with psoriasis, whereas all the controls did not have any bacterial DNA in their blood at all. So, in some, not the majority, but in some, you found bacterial DNA in the blood of those who had the condition, whereas no one who was in the group where they did not have the condition had bacterial DNA in their blood. So that that's saying that that for for me is is already, okay, there's something going on here. The systemic inflammatory response was higher in the patients, the third of patients who had bacterial DNA in their blood compared to the other patients who had psoriasis but didn't have bacterial DNA and obviously the controls as well. So that's showing again, just looking at this paper in isolation. So I have to, you know, confirm that we're just looking at one paper. We haven't got the magnitude of other papers that have conducted this in the same way that would make this a more robust hypothesis or a more robust conclusion. But that's already saying to me, bacterial DNA in those patients who have psoriasis is associated with a worse disease outcome, i.e. higher levels of inflammation. And the bacterial species origin corresponded with the flora that is commonly found in the intestinal lumen. So, again, that that's just saying the bacteria that you found in the in the blood is not necessarily not necessarily abnormal, it's just normally found in in the digestive tract. It's not normally found in the blood, of course. So the conclusion of this paper was that the presence of bacterial DNA in the blood might identify a particular subset of patients with a more aggressive course of psoriasis. And the bacterial DNA, you know, being detected in the blood of patients with psoriasis may have their origin in the intestinal lumen. That that for me was was pretty fascinating and I think this needs to be, if it hasn't already, been repeated to see, answer a few outstanding questions. How they how these bacterial DNA might be impacting the skin? Is this a cause or a consequence of of psoriasis in itself? And we're going to find a lot more of this to come, I'm sure. The way you can sort of conceptualize this is if, uh, you if, let's say, the issues with psoriasis are due to a disrupted gut system, your normal bacteria would erroneously find its way into the bloodstream that could be worsening the psoriasis. And if you had more bacterial DNA in your bloodstream, that's associated with a more severe illness. Or the other way you could look at this is, well, if you've got a more aggressive course of psoriasis, that can impact your gut and that can lead to bacteria being in your bloodstream. It doesn't necessarily mean that bacterial DNA in your blood is causing the issue. So there's two ways of looking at it. So I just wanted to remind people it's not like a an open and shut case, but I thought it was interesting nonetheless and that's a particular way of thinking that a lot of people are coming around to that, you know, the gut can have direct impacts via those metabolites and the bacteria themselves. Okay, so that's the gut. We're going to talk about the other way by which what we eat impacts the skin and that's through nutrients absorbed in our bloodstream. So, vitamin E, omega-3, zinc, they're really important for the functioning of of skin cells. In addition, different cells can utilize these nutrients. So when I say in addition, I'm just talking about the the mechanism here. The the ways in which cells can utilize these nutrients is via nutrient signaling pathways, which simply put is how cells communicate and how they receive, how they process and transmit signals from their environment and within themselves. And that is regulated by the availability of different nutrients. Nutrients being macronutrients as well as the micronutrients that I just described, vitamin E, omega-3, zinc, etc. So, something that's less controversial. So something that's pretty generally well accepted is that a diet high in refined carbohydrates and saturated fats could lead to a deficiency in nutrient signaling, which is why we see associations between a high GI diet and acne, for example. So, some of these nutrient signaling pathways control the process of lipogenesis, the generation of fats in the sebaceous glands of the skin. These are a group of cells that release a fatty substance called sebum to the surface of the skin and that protects skin against friction and keeps it moist. It it and as you can imagine, it needs to be produced in controlled amounts. So again, it's all about balance. Too much or too little can contribute to skin problems such as acne or dry skin or oily skin. So again, all about balance. So the nutrient signaling pathways that are thought to be involved in sebum production have long and weird and wonderful names. So I'm just going to go through this bit. So just bear with me for about 30 seconds and hopefully you'll get an idea of what I'm talking about. So high GI diets that are thought to be involved in the production of excess sebum, which leads to things like acne. The reason why they're they're thought to impact acne is through nutrient signaling pathways and nutrient signaling, well, the the the factors involved in nutrient signaling. The one that's commonly referred to is called IGF-1 or insulin growth factor. And that again, through a different number of different cascades where they interact with other molecules with long and weird and wonderful names like metabolic forkhead box transcription factor one and mTOR, which is the mechanistic target of rapamycin. All these things that you don't really need to know. Basically, through a number of different uh uh uh elements in this in this cascade, mediate, impact sebaceous gland proliferation. So it it it accelerates the production of all those different fats involved in the development of excess sebum, which can contribute to acne. Bear in mind, that's just one one mechanism behind it. There are multiple different mechanisms and multiple different reasons behind the development of acne in itself. So I just wanted to give you an idea of like, okay, that's how diet can impact your nutrient signaling pathways. And a diet that is much higher in whole grains and lower in excess sugar, or just lower in sugar in general, that's one way in which you can harmonize these normal normal attributes of skin function. To round off what is like a very complicated subject is the a third way, which is something I haven't completely discussed in general, which is the the gut brain skin axis, which is explained in another episode on acne. It's episode 122. Basically, psychological stress can impact the gut bacteria to produce different neurotransmitters, which are signaling molecules, and that can potentially change the permeability of your gut, which as we know now, can potentially impact your skin as well. So basically, anything that can disturb your gut barrier can manifest as a skin complaint as well as other complaints as well, which is why looking after your gut is so important. So there is a third way and that's the psychological way as well. So, yeah, looking at all these different things, I don't want to I don't want people to think about these mechanisms in isolation because the likelihood is that multiple things are at play. But we can do a lot by changing our our diet and according to what we know from the the research studies out there, it can be relatively simple to do as well. Okay, finally, let's let's actually talk about food now. So, the general requirements for healthy skin, essential fatty acids. They're used by keratinocytes, which are in the epidermis, and it's very important for normal skin balancing function. Variety of vitamins and minerals. So these serve as enzyme cofactors, activators or inhibitors. Again, good for normal skin function. Antioxidants. These help counteract the effects of reactive oxygen species, a normal byproduct of exposure to radiation and oxidizing chemicals that we're all exposed to as well. That's a general requirement. And hopefully by now, very quick summary, you know that the importance of a diet that's high in fibre and and nutrients to appropriately feed your gut microbes to allow them to perform their function of looking after your your gut barrier integrity as well as your immune system, very important. And then also those different nutrients to regulate nutrient signaling pathways appropriately and their potential more effect as well. But the question I always get are, are there specific foods and how can we incorporate those into our diet that can help with skin health generally and maybe even in a in a treatment capacity as well. This is this is why we developed the Doctor's Kitchen app to help make nutritional research applicable to everyday life. Because when you choose skin health as your health goal in the app, you're suggested a selection of different recipes and these are based on specific whole foods, nutrients and dietary patterns that have been associated with the prevention or treatment of skin problems. And to come up with these ingredients, I just want to give you a bit of background here. We searched through a huge database of scientific literature using PubMed and Cochrane to identify those studies looking at diet and skin. And then we screened each and identified the article for eligibility based on pre-established criteria such as the type of study and the population studied and what they were actually looking for as well. And then we analyzed these selected research papers and extracted the results to create a detailed spreadsheet and that looks at the individual ingredients as well as dietary patterns. And using that, that was the basis for our skin health recipe filter to to refine, okay, which recipes out of our huge library of hundreds of different recipes are associated with or could be reasonably associated with better skin health. So that that's a lot of what we've done in the background as well. And that's just the start for the Doctor's Kitchen app because we've got aspirations to personalize it even more using even more sort of data from the individual. So you know you're eating according to what would optimize your health or your particular health goal, within reason. You know, there are so many other things that we can do, but, you know, at least your diet is going to be on point as much as possible. So, let's start off with the the dietary principles or the dietary patterns that are most linked to skin health. Mediterranean diet, of course, I'm just going to say it. So, as a quick refresher of what the Mediterranean Mediterranean diet actually consumes of, what it is. Well, it's it is a traditional eating pattern that's found among populations living in the Mediterranean basin using during the 50s, 60s of the the 20th century. And it's characterized by a high consumption of natural fats, namely extra virgin olive oil and nuts, a high consumption of minimally processed, locally grown vegetables, fruits, legumes and cereals. These are all unrefined or largely unrefined. There's a moderate consumption of fish and shellfish. That that's actually variable because it depends on their proximity to the sea. But that that was the main source of protein. And moderate consumption of red wine. Everyone always wants to point that out to me. And the reason why I like the Mediterranean way of eating is because it's palatable, it provides a rich selection of micronutrients and polyphenols. You know, you've got hydroxytyrosol and tyrosol, oleocanthal from olive oil. We've discussed that at length on another podcast talking all about olive oil. Yes, you get like resveratrol from nuts and and grapes and wine. All of these have anti-inflammatory properties, which as you can imagine, anything that is high on that dietary inflammatory index, that anti-inflammatory score is going to be beneficial for skin issues, particularly if you do have a complaint as well. And it's going to be good for your gut, which is obviously going to be good for a number of different things, including skin. It's also characterized by a low consumption of meat and animal products in general. It's, you know, usually reserved, their meat consumption is usually reserved for special occasions. And very low consumption of processed foods as well with the exception of fermented dairy products, aged cheese and yogurt as well. That that's moderate consumption. And the other reason why I like the Mediterranean diet is because it doesn't necessarily need to be Mediterranean flavoured. It's just a it's a principle. It's a a pattern of eating that you can apply that using the lens of different cuisines. So it doesn't, you know, it could be Indian flavoured, it could be flavours from different parts of Africa, East Africa, West Africa, you know, it doesn't necessarily have to be aubergine, lentils or radicchio or, you know, olive oil over wild greens salad. It can be according to how you want to eat as well. I've already discussed why it might be beneficial for for skin, but it's it's fairly obvious if you've been listening to the first part of this podcast because a high adherence to the Mediterranean diet is associated with all those different antioxidants, including beta carotene, retinol, which is a pre-formed vitamin A. It's got vitamin C and E because you've got lots of cooked and uncooked vegetables in those diets. You've got high intakes of B vitamins. And it may benefit the skin by all those different mechanisms that we've described already. Reducing oxidative damage to the DNA, increasing your skin's innate ability to neutralize those free radicals, also known as reactive oxygen species. It may even contribute to limiting or alleviating skin photo damage from UV radiation. That's actually something I discussed in my second book, Eat to Beat Illness, about how there your food can have a photo protective effect, which can reduce uh uh the the issues around premature aging. Not better than sunblock and not better than getting out the sun or limiting your sun exposure, particularly during periods of the day where there's more radiation. But interesting nonetheless. And I I I think it's quite a niche opinion on diet and skin because what these ingredients have demonstrated as a photo protective effect, but we don't necessarily think about that. You know, especially in Australia, it's like, I forget the I forget the saying now, but it's like slip, slap, slop or something like that. It's all, you know, focused towards getting out the sun and putting on sunblock. But actually your your diet could have an additive effect. How much, I can't really quantify, but at least a little bit at least, I know that. The Mediterranean diet is also associated with low intakes of saturated fat and high intakes of your omega-3 polyunsaturated fats that you get largely from fish, but you do get small amounts in nuts and seeds and olive oil as well. And they that that might benefit the skin by regulating inflammation and balancing the production of fats from the sebaceous glands that we referred to earlier. The other way is, you know, it's it's very low in refined in refined grains and excess sugar. So that's going to be appropriately uh uh it's it's going to be causing appropriate nutrient signaling. There are some results from observational studies that show that a greater adherence to the Mediterranean diet was associated with reduction in inflammatory factors such as C-reactive protein and other interleukins. And as an aside, chronic inflammation is linked to various skin problems including cancer. In fact, there was a study um uh looking at the Mediterranean dietary pattern and skin cancer risk from the American Journal of Clinical uh clinical nutrition 2019. And researchers analyzed data from it was almost 100,000 French women born between 1925 and 1950 as part of another study, that's what they were recruited for. And this prospective cohort study were enrolled to to answer the question around skin cancer and diet. And and bear in mind this is an observational study, it's one of the lowest uh in terms of the hierarchy of evidence. But what they found is that a higher score of adherence to the Mediterranean diet was associated with a significantly reduced risk of skin cancer. And when you look at those individual components of the Mediterranean diet that we just discussed, you can you can understand that it's not just about the individual nutrients, it's about the cumulative effect and the synergistic effects of multiple different foods that can have a beneficial effect on skin health in general. So, yeah, looking at patterns of eating, the dietary pattern, anything that can align with a Mediterranean diet is certainly something that you could appropriately associate with a skin health goal as well. Let's move on to specific nutrients. So when I say nutrients, we're talking about like specific uh micronutrients themselves. Omega-3 fatty acids that I've already mentioned. There's actually mixed evidence. And we're very we're very forward thinking when it comes to the the mixed evidence. And we want to be as transparent as possible, which is why we've included our sources on the doctorskitchen.com where even if there is counter evidence, we do want to include it in our discussion because we don't want to shy away and just cherry pick. We want to look at all the various um uh sources of evidence and make a balanced uh decision uh based on pragmatism. So, just as a primer, omega-3s are polyunsaturated fatty acid. It comes in various forms. You've got the short chain LA and ALA, which is linoleic acid and alpha linoleic acid. And you've got the long chain, which is EPA and DHA, which is uh I I always forget the names, but it's like eicosapentaenoic acid and DHA is docosahexaenoic acid. I might have to check that. But DHA and EPA, you'll find those in oily fish. You'll find it in some algae-based supplements, but largely it has to be converted into EPA and DHA, which we don't do very well, which is why it always bugs me a bit where you'll see a plant-based product labeled as with the exception of algae supplements, labeled as high in omega-3, but actually it's just high in omega-3, which is the short chain, not the long chain, and you want to get the long chain EPA and DHA. And they they're considered essential fatty acids because they cannot be synthesized by humans. The reason why omega-3 fatty acids are important for skin is because they form components of skin cells and they're involved in the control of various cellular functions by regulating inflammation as well. They also act on a variety of immune cells. So they they suppress immune cell migration, which is which is good, particularly if you do have an issue with an over-ramped immune system that could be causing the skin problems in in the in the first place. So they they actually influence the production of inflammatory signal molecules, they regulate the expression of proteins related to inflammation, inflammation, they they activate and and inhibit toll-like receptors, which again are involved in the immune system process. So very, very important generally to get omega-3 fatty acids into our diet. You can do that by supplements or by diet, and I choose both. And uh, yes, that they they there is a suggestion that they're involved in UV radiation and and thought to be photo protective macronutrients, i.e. larger molecules with beneficial effects on UV radiation, but, you know, there's only so much that you can do with diet in terms of protecting ourselves from radiation. The research, like I suggested at the start, is suggesting mixed results for their impact on skin conditions. So there was a study looking at omega-3 fatty acid supplementation. I'm just going to give you the very top end summary here rather than go through all the details, but that reduced psoriasis severity. That was in 2019. That was a positive result. And then another study where fish oil supplements were used had no effects on the severity of psoriasis. That was Yang et al in 2019. Again, the same year that the other study that I just mentioned, um, uh, suggested a positive result. Um, the there was a meta-analysis of uh, and a meta-analysis sounds really impressive, like, oh, all these studies and and uh, and it showed this uh, general effect and it was significant or whatever. Um, actually meta-analysis, it really depends on what you put in the meta-analysis. Just as a as a um, uh, refresher, meta-analysis is where you combine the results of multiple different studies looking at the same uh, uh, question and hopefully using the same methodology as well. But what you'll find, especially if you're scraping the barrel for studies, is that they'll use a mixture of all these different types of studies in their analysis. Sometimes not using the same methodology, sometimes very, very poorly conducted as well. So it really depends on what you put in. And this meta-analysis is a good example of that. It only had three studies used in it with a with a total of 337 participants. So again, very, very small. Um, and they found that fish oil supplements had no effect on the severity of psoriasis. So what do you do with these results? There's only so much that you can do. Using a pragmatic approach, I think omega-3 is a very important um, uh, component of the diet. There are some benefits for cardiovascular health, um, brain health as well. And so, you know, it's not something that I would uh, omit just because it's not good or it hasn't been shown in current studies to be beneficial for skin health. I think there's definitely a lot more to find out about omega-3 in general. Um, so yeah, getting it getting it into the diet as much as possible and even supplementing would be something that I would uh, I I suggest. Other minerals, zinc, an essential mineral, we have to consume it from food. It's found in nuts and seeds. It's also found in things like eggs, seafood, meat, seeds like pumpkin seeds, sunflower seeds, sesame seeds, nuts like pecans, cashews, almonds, very, very important uh, uh, mineral, micronutrient. It supports the normal function of skin cells, regulates inflammation. As you can tell, inflammation is going to be a recurring theme uh in this episode and many more coming forward. Um, it could actually be involved in the regulation of our adaptive and innate immune responses by reducing neutrophil chemotaxis. Chemotaxis is the movement of those cells, it's just a fancy word for movement. Um, inhibiting, well, I'm not going to just say the names here, but inhibiting T helper cell activity. That basically is about immune tolerance. So making sure that you don't have an overly active immune system. Um, and a whole bunch of other things impacting a number of different cells that there's no point talking about because it's it's hard to conceptualize on a podcast and it's just confusing. So the the evidence around zinc uh is is interesting as well. So there was a 2019 study, it was a systematic review of all the literature combining 22 studies and they found that supplementation with zinc was beneficial for acne and uh another condition called hidradenitis suppurativa. Um, but it remained unclear for other skin conditions. So generally, what we know about zinc is that it's easily found in the diet. That's the first thing. And it potentially does have an impact on your immune system and the correct functioning of your immune system. Um, and supplementation was shown to be uh potentially beneficial as well. There are a number of different limitations of all these different studies including various methodologies and the the dosing and zinc formulations and and how comparable all these studies are and stuff. So that's just something you have to you bear in mind when you're thinking about this. Which is why I'm not a big fan of supplementing individual uh uh micronutrients with with some exceptions, like omega-3 for example. Um, the majority of what we talk about through the lens of of uh nutritional supplemental studies can be found in the diet. And there are so many other attributes of a healthy, diverse, balanced diet that it's it's hard to ignore. Another interesting ingredient, green tea, probably attributed to the catechins, which is one of the polyphenols you find in green tea. It's been shown to reduce inflammation and potentially beneficial for uh skin issues as a result of UV radiation. So again, another potential photo protective effect. All right, let's move on from supplements and look at whole foods because there's a whole bunch of different supplements that have been tested like flavonoid supplements, um, vitamin C and E and stuff. And they all have relatively mixed results. And I and I think they're less interesting because you can find good amounts of those in in the diet with the exception of vitamin D. Fruit contains a wide variety of different vitamins and phytonutrients that enter the bloodstream to feed our organs and tissues. They contain all these different things like flavonoids, carotenoids, as well as your traditional essential micronutrients like A, C and E. How nutrients impact the the skin? Well, nourishing the skin barrier, the um gut barrier, I should say, regulating inflammation. Several nutrients in fruits can serve as something called methyl donors. These are chemicals that impact the expression of our genes. So not changing the sequence of your genes, but changing the way they function. This is the whole concept of epigenetics that we've talked about in in previous podcasts. Um, so that can actually prevent the expression of inflammatory genes as well. And that's been shown by the consumption of different fruits and vegetables, but fruit as well. Ultimately, all these different things reduce inflammation. As a as an aside, I think it's an important point to pause on for a second because with nutrition and certainly online, you'll you'll see people demonizing particular foods by looking at it through the lens of a particular characteristic, i.e. its impact on glucose levels. And whilst I think that's interesting to note that, you know, this particular ingredient causes a spike in glucose, it doesn't necessarily mean that you should never eat it because the way in which you eat said ingredient, whether you've had a meal before, whether you're eating it on an empty stomach, whether you're combining it with something else, that has an impact on things like glucose levels as well as all the other impacts it can have as well on nutrient signaling. So it's it's really important that you shouldn't detract from the you shouldn't detract the positive effects from one particular ingredient just because of one singular quote unquote negative impact. And I think glucose, as much as I think continuous glucose monitors are going to revolutionize personalized nutrition, it's just something to bear in mind because I I do see that quite often. Um, and uh, you know, we don't give as much attention to the other things that are less tangible like the reduction of oxidative stress, the suppression of inflammation, the impact on gene function, which are, you know, it's it's less um, you can't see that. Um, and obviously, yeah, the other ways, you've got nourishing the gut barrier, regulating inflammation, and then reducing oxidative stress as well because fruits and vegetable or fruits, they have vitamin A, C and E and those help our antioxidant defense systems, they reduce those oxidative species and they protect the skin from cellular damage from the free radical excess of free radicals. There is a potential fourth way by which fruit can impact the skin and that's via promoting collagen synthesis. Um, so potentially because of its uh vitamin C and vitamin E and other essential micronutrients that are important for the the structural components and putting all the collagen pieces together. Um, but uh, yeah, more more information on that, I think needs to come through because I I believe it's also due to making sure that you've got adequate levels of protein in your diet, which you can get from a largely uh plant-based diet and a Mediterranean diet essentially. There are a number of different studies that have shown though that that showed the association between high fruit intake and lower risk of various issues including seborrheic dermatitis. But we're not going to go into those because I think the observational nature of them limits them and by now, I think you're you're definitely getting the impression about, okay, you need to eat your fruits and vegetables. Kale and cruciferous vegetables, I do want to talk about specifically. There's a really lovely uh study looking at why these might be impactful. Um, kale being a cruciferous vegetable, it contains a variety of different phytonutrients, glucoraphanin, which is a precursor to sulforaphane, which has has had a lot of attention recently as being quite a powerful anti-inflammatory molecule. They also contain things like flavonoids such as quercetin and kaempferol, carotenoids like beta carotene and lutein, vitamin C and K, dietary fibre. These are all released into the bloodstream following digestion. They all act on a variety of different targets and they all also contribute to a healthy microbiota. So you can see the the the multifactorial ways in which having these different types of ingredients into your diet can enhance the production of different skin components like collagen and hyaluronic acid, improve the skin homeostasis, improve the immune system so it's tolerant and not overactive. And may even reduce dryness and other skin problems as well. There was a an a really interesting Japanese study looking at the effect of kale intake on participants with skin dryness. So, this this was interesting. There were two studies conducted by the same team, a randomized double blind placebo controlled parallel group study. So, randomized being before the study, independent researchers assigned the participants to different groups using a computer generated code. So they're selected by chance. And the reason why you do that is to reduce bias. It's double blinded. I don't know how they did this, but um, they blind, they blinded the uh researchers involved in the experiment as well as the um people themselves. Um, so they had a kale uh extract and then they had a placebo extract. So there was it was blinded in that way. Um, and they gave this to it was a small study, 44 healthy Japanese women aged between 30 and 60. And they were randomly assigned to either take the kale or the placebo. And it was over 12 weeks. And what they measured was validated by skin moisture content, transepidermal water loss, colour difference and the visual judgment by a medical specialist and using something called a visual analog scale. So they use pretty robust measures of how you would see any improvements in skin. And after 12 weeks, what they found was that the participants eating kale that had a actually I should should mention it had a recognized 20 milligrams of glucoraphanin in the in the kale intervention. And that's something that you find naturally in kale. For 12 weeks, increased their skin moisture content, reduced their skin dryness compared to the placebo group. So there was um that that was quite an interesting outcome. And the same study group did an in vitro study trying to figure out what the potential mechanisms were. And what they found is that glucoraphanin and sulforaphane, which is another component of cruciferous vegetables, significantly enhanced their capacity to produce collagen and hyaluronic acid. So these are the the components of skin that people are buying and slapping onto the skin and all the rest of it. We don't really have great evidence for the effectiveness of that. But it it seems that you can you can potentially enhance the the innate production of it by having cruciferous vegetables. Again, lots of limitations of this study, uh lots of things that we still need to find answers for. Interesting nonetheless. I think it's really interesting and that's actually why we have kale as one of our um contributing skin health recipes. That's definitely something we we want to we want to do more of. Moving on, we've got lingonberry and amla fruit. Um, this is one for the Swedes and Indians. Why might it help with the skin? Well, lingonberries contain things like flavonoids, resveratrol, quercetin, catechin, epicatechin, coumaric acid, as well as other polyphenols as well. And amla contains, which is a sour mango, you usually find it in powders. Um, and it's um, it's delicious. It gives that a lovely wonderful element to curries. Um, it that contains phenolic acids, gallic acid, gallogen, vitamin C, as well as a whole bunch of other polyphenols. It it's pretty unclear exactly how these components contribute to the effects on skin. However, the suggestion is that because they're so high in different polyphenols, they exert their antioxidant effect and that can impact cellular damage and inflammation. They may be able to, again, assist in the production of collagen, which by now everyone knows contributes to skin elasticity and something that generally degrades with age. They may also promote the production of something called NMFs, natural moisturizing factors, or hyaluronan in the keratinocytes and dermal fibroblasts, fancy word for some of the cells that you find in that layer of the skin. And that regulates the water content and improves skin moisture. So again, some other mechanisms similar to kale. Interesting nonetheless. Uh it's the evidence showing is um is quite interesting. There was a study intervention study on 99 healthy participants. You're getting the impression that all these studies are small and they are. Um, and the effects on lingonberry and amla fruit extract on skin conditions was examined. I don't know why they combined them. Um, maybe they were just looking at very high polyphenol content uh ingredients, but I just thought it was a a bit strange that they they combined them because from a culinary point of view, I don't think they would they're both quite sour, I guess, but yeah. Anyway, um, 12 week study again, two groups received drinks containing different doses of lingonberry and amla and the other was a placebo. It was double blinded in the same way as the Japanese study. Um, and uh they had different uh amounts in three different arms. So they had a 25 milligram lingonberry and 30 milligram amla fruit intervention. They had a drink containing double the volume of the same extract, so double those amounts. And the third one was a placebo. And what they measured was elasticity, skin thickness, water content and the degree of wrinkles as well. Um, and what they found was that the interventions improved outcomes across all those different uh measures. So skin elasticity, skin thickness, water content and the degree of wrinkles all improved and were significantly higher in both the experimental groups with the single and double doses of those two ingredients than the control group. Importantly, these results were actually replicated, which is which is pretty major actually. Um, a previous study by the same team found that the skin elasticity improved after eight weeks of the the combination drink intake. So this is actually a replicate replication of a study. Although it was the same center, so that that is a limitation. And in the present study, they found that it was dose dependent. So the higher group had a better outcome than the single dose group. So, yeah, it I mean, with all these things, you have to take them with a pinch of salt or a pinch of amla. Um, and uh, I I think it it's important to note the the limitations, but also it's exciting because there isn't much of this stuff being done. Uh it's quite hard to scrape the the academic literature to find it. And when you do and you find results like this, it raises your eyebrows as it should do you as well. What we can what we can take from this aside from going out and getting lingonberry and amla supplements is it's likely due to the combination of high polyphenol ingredients. And it provides evidence of the stronger effect of nutrient combinations rather than individual effects. And I think first of all, the individual effects need to be clarified in future studies. But it shows that if you do include high nutrient dense ingredients into your diet, whether that be through drinks or whether it be through delicious recipes that you can find on the Doctor's Kitchen app, that that's a way of improving all these different parameters. Aside from having to, you know, spend money on expensive supplements. So, just from a an interest point of view, hopefully this does peak your interest because there are ways in which we can naturally include these components into our diet with the intention of not just improving skin characteristics, skin uh uh skin health, but also other elements of health as well. Other fruits in that in that vein that would have similar nutritional values are things like berries, blackberries, blueberries, green tea, spices. So, you know, I don't want to suggest that you can only get this effect from lingonberries and amla. I think it's reasonable to assume you can potentially get similar effects in other food products with high polyphenol concentrations. And we've actually done a lot of the research looking at all the different types of polyphenols that you find. We've extracted that data from sources like Phenol Explorer, which is the world's or at least Europe's biggest um uh plant chemical database on various ingredients. And we use that information, that rich source of information to uh look and and and clarify which ingredients have the highest amount and then we we make recipes from those as well. So you'll, you know, you won't find an amla or lingonberry recipe unfortunately on the uh on the app, but you'll find lots of other more accessible ingredients that you can find into your diet. We're going to talk finally about fermented dairy products such as yogurt. So, fermented products, just as a refresher, contain probiotics, which are live organisms which when administered in adequate amounts can confer a health benefit to the host. That's the definition of what a probiotic has to adhere by for it to be labeled a probiotic. And there are certain uh microbes like Saccharomyces boulardii, lactobacilli, bifidobacteria, all these different types that have got recognized status within the EU as being probiotics. So when you when you put those into a product, you can reasonably label it as a probiotic. How might they help promote the skin? I I feel like you're going to be able to get the answer here. Promoting good intestinal health, which regulates the gut skin axis, which is the main way that most people believe probiotic foods can impact positively your skin health. We now understand these indirect and direct pathways that we discussed earlier. But also, they may promote the production of ceramides. These are specific lipids or or fats, waxy fats that trap moisture in the skin. We also know that it potentially reduces inflammation as well, i.e. dairy products and their impact on intestinal permeability, mediating major immune components. So keeping your immune system in harmony and reducing um uh the penetration of products in your gut that should be in your gut and not in your bloodstream as well. All of these different functions and attributes of probiotic uh products such as yogurt, um all help maintain skin function. There is um there are some studies, some studies looking at uh the relationship between fermented dairy products in particular and skin health. Um, there was a systematic review looking at the results of three different studies, again, small amounts, looking at the relationship between fermented products and skin health and they found that uh the consumption of fermented dairy products were associated with uh better skin. So, again, limitations, lots of limitations in everything that I'm talking about, but you can find probiotics in kefir, miso, fermented beverages, sauerkraut, kimchi. Um, overall, we're going to do another podcast all about fermented foods in in another health goal section. But fermented foods are one to get into your diet generally, I think. The net positive despite the lack of robust, robust evidence is uh is pretty clear. So I I want to end this podcast now in in full transparency by pointing out that after looking through all these studies and all these mechanisms, nutritional medicine can be vague and we can only do the best with what we have. We are we're obstructed by by studies with poor methodology, which make it harder to critically assess the research. There's obviously the the elephant in the room, which is the lack of studies, the lack of funding for studies. There is also a lack of diversity in population studies. You know, we've talked on the podcast about how a lot of the research is conducted on non-generalizable populations with a particular um reference to people of ethnic minorities as well. And that's, you know, I don't think we've got a single study that looks at a non-Caucasian population of of various age groups. Um, which is a shame because I think again, in an era of personalized medicine, which is what we're going to be moving toward, we we definitely need to have those foundational studies to make accurate hypotheses because we are we are different in lots of different ways. So how applicable are these results to the wider population? I'm not too sure. I can't say that with any certainty. But I I I believe that what we eat and how intuitive we can be about what we eat is generalizable. So, yes, I I think given the limitations, we we have an idea, but the future does require a little bit more um diversity in the in the way we do research. The uh the use of questionnaires to assess dietary intake comes with many limitations. And unfortunately, a lot of the studies that we we look at are observational in nature, which means they're self-reported, uh the participants self-evaluate. And if you've ever tracked your own meals, you you're probably be aware that you under report what you consume. And that's it's quite a well-recognized phenomena with uh food questionnaires. They're they're fantastically inaccurate. Um, and most studies also looking at the health goal in particular, skin health, most studies look at skin conditions, which which limits how much we can attribute these kind of dietary principles to normal skin health. So the skin health goal is not necessarily to treat a skin condition, it's to optimize your skin health, which I believe actually is the way we we do treat skin conditions is by giving uh the the foundational factors for your skin to look after itself rather than having to treat it in the same way we would use a pharmaceutical. Food food in my mind is not equivalent to a pill and it shouldn't be seen of that. It's more of a mechanism of of enhancing your own defense systems. That that's just one element of it as well. And even when you look at meta-analysis, the the higher tiers of research, if you compare it to observational, um, if you get a mixture of different methods and a mixture of different uh, um, ways in which or questions that they were trying to answer, it's very hard to generalize and it's probably it can be pretty useless, which is why we we chucked out a lot, half the stuff we haven't even discussed. Um, so you're probably asking yourself, what's the point? Is this is this still relevant or is it a waste of time? I think so. I think it provides a foundation for future research. I think it indicates what we can do right now. I think it's it's a good guideline on what to eat blended with plausible mechanisms and common sense. And it's interesting to note that this is potentially how things are working in your body to optimize various aspects of health. And this the skin health goal, I think is um it it's great because I'm I'm always asked about that. And the way we created recipes, we compiled all those nutrients and whole food recommendations extracted from the research into this big spreadsheet. And then to ensure each recipe met the recommendations, we generate that formula to either validate or reject the ingredients as to whether it's aligned with these criteria. So this amount of detail, that's how we we we we label the the the recipes as either skin health friendly or something else friendly. Each recipe, we actually enter the ingredient amounts into this into this spreadsheet and we check whether they're actually beneficial for skin health according to these pre-established criteria. So we're we're dragging out the opinion of what someone might look at and say, oh yeah, that that's good for skin health because it contains a bit of blackberries. And we're actually looking at the amounts and actually like, no, this needs to go up or we actually have to include something else to make sure that it aligns with the Mediterranean diet um uh tool that we have. So this removal of personal biases and opinions from whether we think something should be good for skin health, if the algorithm says it is, then it is and vice versa. And this ensures that the recipes in the app are using an evidence-based uh approach. And also, notwithstanding the fact that we want to create flavourful, practical recipes for everyday meals to ensure you meet your nutrient needs and support the function of your skin. So, all we want this to do is provide a foundation for further research so we can further personalize our simple algorithm. And one day, it'll be able to tailor specifically to your needs based on preferences, which you can do already. But we also want to introduce other sorts of um investigations, gut microbiota testing, genetic uh investigations, activity monitors, even responses to food like blood sugar, inflammation, as well as the subjective scores of wellbeing. And don't forget about taste. Taste is so, so important and I think a lot of a lot of other apps, um, well, there aren't other apps doing what we're doing, but I think a lot of people don't really think about the the pleasurable aspect of eating as being super important for psychological wellbeing as well as physical wellbeing as well. So, some of the skin health recipes you can find in the app include berry granolas made from scratch using nuts and seeds high in vitamin E, zinc, vitamin C. Um, there's one pot stews with cruciferous vegetables, there's beautiful warming spices and healthy fats to help the absorption of those fat soluble vitamins. And there's lots of crossover with all these different health goals. So what's good for your skin is likely going to be good for your brain, your heart health and even mental wellbeing. So you might see a combination of different health goals that align with the recipes that you're choosing through the um uh through through the app that align with like brain health and mental health as well. I'm going to wrap it up here. We've talked a long time, or I've talked a long time about all these different things. So I really hope you found today's podcast educational, maybe entertaining, who knows? Um, I don't think it was that funny. And uh, I hope it gives you an idea of the complexity and the magnitude of nutrition as well as what we're trying to achieve with the app too. So, we're going to be doing deep dives into all the health goals over the next couple of weeks. And if you have suggestions of other areas, we'd love to hear about them as well. And I think the main idea is to give you an understanding of the complexity and the interconnectedness of the human body and nutrition, why it's so powerful, and how food can be used as preventative and supportive medicine. Remember, you can check out the app. It's at the top of the show notes here. You can download it for free. There's a seven-day free trial. Uh, I love your opinions on it. Share it with your friends and join the journey because we are going to be making this better and better and it's our sincere goal to make sure it is the best app that you have on your phone. Thanks a lot and I will see you here next time.
