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REPLAY: Asthma, inflammation, nutrition, and the lung biome with Dr Michelle Woolhouse and Professor Lisa Wood

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REPLAY: Asthma, inflammation, nutrition & the lung biome with Michelle Woolhouse and Prof Lisa Wood

Join Professor Lisa Wood, Head of School of Biomedical Science at the University of Newcastle, and our ambassador Dr Michelle Woolhouse for a conversation on asthma and lung health. Together they discuss the impacts of fibre, prebiotics, and the inconclusive research on omega-3s in the treatment of inflammatory lung conditions. The intrinsic link between the lung and gut microbiome is also explored, as well as the impact of air pollution and diet on asthma, and the role of saturated fat in inflammation.  

The importance of fibre in reducing lung inflammation and the emerging research on modulating the gut microbiome to influence the lung microbiome are also discussed. Solutions to asthma management are discussed, which include encouraging patients to consume a high antioxidant, fruit and vegetable-rich diet and exercise to reduce inflammation. Finally, the impact of obesity on asthma symptoms and steroid effectiveness are covered, stressing the need for a healthy weight. 

Covered in this episode

[00:33] Welcoming Professor Lisa Wood
[02:24] Prof. Wood’s background and what piqued her interest in this area
[03:54] What you eat affects your lungs
[05:40] Fats and impacts on lung immunity and inflammation
[11:39] Short chain fatty acids as anti-inflammatory
[15:29] The benefits prebiotics and soluble fibre
[18:08] Do omega-3 and -6 fatty acids 
[19:58] The lung microbiome and asthma 
[22:21] Pollution and the hygiene hypothesis 
[27:29] Impacts of exercise on asthma
[30:19] Nutrition and the effectiveness of Ventolin
[32:38] Obesity and steroid-resistant asthma
[35:34] Pathophysiology of obesity and how that relates to asthma
[38:35] Nutrition and lung inflammation
[42:41] Thanking Professor Wood and final remarks

Key takeaways

  • Our diets (especially saturated fats and omega-6) have a great influence on lung health as there is a strong vascular link between the lungs and gut. Because of this relationship clinicians need to target diet and gut health where patients have pulmonary health issues.  
  • Research shows excessive saturated fats can initiate the same immune response as a pathogenic microbe by binding to immune receptors. 
  • Short chain fatty acids produced by the gut microbiome, particularly acetate, is transported to the lungs and has anti-inflammatory effects.  
  • Probiotic research may still be inconclusive however strong research around the use of prebiotics shows their ability to aid in production of beneficial compounds and change the composition of the microbiome in the lower gastrointestinal environment which aids suppressing growth of problematic bacteria. 
  • Emerging evidence suggests that changing the gut microbiome may have an influence on disease outcomes for lung disease (COPD). More research is to be undertaken to elucidate this mechanism in humans to improve disease management. 
  • Environmental effects of pollution can be counteracted through a high intake of dietary antioxidants. 
  • Research has found that meals highly concentrated in saturated fat reduce the effectiveness of Ventolin by reducing the bronchodilatory effects. 
  • Obesity is detrimental to asthma sufferers. Adipocytes are inflammatory (increases risk of worsening symptoms) and obesity is linked to steroid resistant asthma treatment.  

Resources discussed and further reading

Professor Lisa Wood
Research: A high-fat challenge increases airway inflammation and impairs bronchodilator recovery in asthma (Asthma and lower airway disease, 2011)
Research: Effect of obesity on airway and systemic inflammation in adults with asthma: a systematic review and meta-analysis (Thorax, 2023)
Research: Airway-delivered short-chain fatty acid acetate boosts antiviral immunity during rhinovirus infection (Journal of Allergy and Clinical Immunology, 2023)
Research: Mechanisms and treatments for severe, steroid-resistant allergic airway disease and asthma (Immunol Rev., 2017)


Michelle: Welcome to fx Medicine, bringing you the latest in evidence-based, integrative, functional and complementary medicine. I'm Dr. Michelle Woolhouse. 

fx Medicine acknowledges the Traditional Custodians of country throughout Australia where we live and work and their connections of land, sea, and community. We pay our respects to the elders, past and present, and extend this respect to all Aboriginal and Torres Strait Islander people today.

One of the most common conditions in Australia is asthma, an inflammatory condition impacting the lives of hundreds of thousands of Australians, especially children. Although we have some well-researched treatment options, my guest today has been exploring the possibility of expanding the treatment recommendations. Due to the potentially severe impact of treatment-resistant asthma, it's at times precarious presentations, and the role of lifestyle medicine, food, nutrition, and exercise is often not emphasised as much as it could be. Professor Lisa Wood has spent most of her career passionate about teaching students these low-cost, multi-system effective treatments and the evidence in which they're backed.

With the rise of interest in immune support, the risk of long COVID on the exacerbations of asthma and other metabolic pressures, there has never been a better time to discuss the attest in innovative and holistic treatment options for asthma and other common lung conditions. Lisa has a passion in this area. She's a nutritional biochemist and registered nutritionist who has been working in the area of inflammation and nutrition for over 20 years.
Welcome to fx Medicine, Lisa. Thank you for being with us today.

Lisa: Thanks very much. Thanks for having me.

Michelle: So, Lisa, I always find it fascinating to hear someone's journey, especially when they arrive each day and work in a niche area of their own creation. So, is there a reason behind the passion that you have?

Lisa: Yeah. Well, that's a really interesting question. I think that one of the driving forces for me was I did my PhD in cystic fibrosis, and I was studying the airways and how nutrition could affect the airways in cystic fibrosis. And as I was working in that area, I came to discover that there was actually not a lot of information about nutrition in any airways disease.

And particularly in the area of asthma, there was some work that came out that showed that over 50% of people who have asthma were modifying their diets to help better control their disease, but there was actually really no information as to what they might do. There were no dietary guidelines for people with asthma, and there was very little scientific evidence to show how you could modify your diet to help manage your disease.

So, seeing that there was that really big gap in knowledge there, that was really what encouraged me to develop a research programme to help try and meet that need.

Michelle: That's amazing because we strongly connect things like cardiovascular disease with nutrition. And asthma's such a prevalent problem, but there seems to be this real disconnect between some of the major diseases that we look at and nutrition. Why do you think that is? And we're going to get into what the role is.

Lisa: Yeah. So, I think one of the things is that people don't intuitively think of what's happening in their lungs being related to what they eat. So, when you eat food, you obviously digest food and, you know, it goes into the bloodstream. And I think people can conceptualise that that would then affect your heart, for example, and people are familiar with the idea of fatty foods clogging the arteries and leading to cardiovascular disease.

But I think people see the lungs as being more distant, but the important thing is that as soon as something enters the bloodstream, it actually is in the lungs because the lungs are highly vascularised and the blood is constantly circulating through your lungs. So that's actually not true. The lungs are very close to what you're eating just through the bloodstream. But I think that's one of the reasons why people don't intuitively get the link.

Michelle: Or, educating. I think "fats block your arteries" was almost like a public health message yet it seems that we don't yet have that public health message in terms of asthma management as well.

Lisa: No, I'm sure that is true, and it really is only very recently that we've started to have specific guidelines around healthy eating and asthma.

Michelle: Yeah, that's exciting. So, you've researched and published multiple papers in the area of dietary fats and their impact on the inflammatory aspects of lung health. So, what do we need to know about the role of unhealthy fats and their impact on lung immunity and inflammation?

Lisa: Well, one of the most fascinating studies that we've done was when we recruited a group of people with asthma and we got them to consume a very unhealthy meal. So, it was a meal that was high in fat, also high in other macronutrients. It was essentially two breakfast burgers and two hashbrowns.

Michelle: Wow.

Lisa: And it was a big bowl of… Well, I know, and it's funny though that amongst the people that participated in this study, probably half of them thought it was really gross, and the other half thought it was great being permitted to eat this unhealthy meal.

Michelle: Maybe we should research that.

Lisa: So, they consumed this meal and then we monitored them over four hours. And this is an example of what I was saying. As soon as you eat something, it is in your lungs. It's in the bloodstream, and then it's straight into the lungs. And within just four hours, we found that their airway inflammation worsened. And airway inflammation is, of course, the underlying pathology of asthma. That's what causes asthma because it's got this inflammatory pathology.

And so that was the first study we did, and it was really a bit of a toe in the water sort of study where we were just putting them in a really extreme situation so that we could see if there was any impact on the lungs because nothing like this had ever been done before. And once we saw that it did have that effect, we then went back and tried to refine it a little bit and so we broke it down into the different macronutrients. So, that meal was very high in saturated fat. It was also very high in omega-6 polyunsaturated fat, and it was also high in simple carbohydrate.

Michelle: Yes.

Lisa: So, we then in our second study, follow-up study, we broke it down, and we used mashed potato as a base vehicle, which is really just digested very quickly and disappears. But then we used that as the vehicle to deliver a high dose of saturated fat compared to omega-6 polyunsaturated fat compared to simple carbohydrate. And we did confirm in that study that it was the saturated fat component that was driving the increase in inflammation, and we've found some really interesting results.

So, people often don't understand how fat could actually cause inflammation, and it's been discovered that the immune cells have receptors on their surface. And when those receptors bind with different invading pathogens, it causes those immune cells to become active and release inflammatory mediators. But what's been discovered in recent years is that actually saturated fat is able to bind to those same receptors on the surface of immune cells, and so the saturated fat initiates exactly the same response as if it was a bacteria that cell is binding to.

Michelle: Wow, that's so interesting.

Lisa: And, I mean, of course we can all eat saturated fat, and we do eat saturated fat, and it doesn't cause major impacts eaten in moderation, but if you've got an ongoing chronic load of saturated fat, excessive saturated fat, then that can stimulate the immune system ongoing which will have detrimental effects. 
So, that was probably the strongest evidence that we've been able to generate that's shown that this type of an unhealthy eating pattern, high in saturated fat, can cause lung inflammation and then contribute to disease.

Michelle: And was there an impact on the simple carbohydrates, like the high glycaemic load, for example, using something like potato, or you mentioned other carbohydrates. So, was that an impact and was it a combination effect or were we...?

Lisa: Well, it wasn't. In the study we did, it wasn't, so you could say that there was an intermediate effect but it wasn't as strong. So, when you do research, you need to be able to make a definitive conclusion about anything you research. You need to have a strong enough effect that, with the sample size you've used, you see a result that becomes statistically significant. 

So, with regards to the simple carbohydrate, you could see that there was an intermediate effect. It wasn't as strong as the saturated fat, so it wasn't significant in our trial, but there was certainly a signal there that would be worth following up in future studies.

Michelle: And also, I mean, in modern day life, I mean, they often go together.

Lisa: Almost always.

Michelle: Yeah, almost always, so it's so interesting.

Lisa: Because fat on its own isn't palatable and as...

Michelle: Yes.

Lisa: ...I just mentioned, so when we did the study, when we looked at the isolated macronutrients, it was actually quite a hard study to design because we did want to separate out those macronutrients, and there's virtually no food sources that do, or no palatable food sources that just have one of those ingredients to make fat palatable. You invariably need some simple carbohydrates or some potato or some sugar.

Michelle: Yes.

Lisa: And then you're bringing in the carbohydrates, so it is actually a very important and a true point that once you start eating high doses of any type of dietary fat, you're usually also consuming other ingredients that might be causing problems.

Michelle: And what about the fats, things like short-chain fatty acids, which are known to be really beneficial for our health and that we tend to make inside our own guts. How are they related to asthma? And should we be looking at how we produce those from our diet and from our gut biome?

Lisa: Yeah. So, that's another angle to the work that we've been doing. So, short-chain fat acids are completely different to the type of medium and long-chain fatty acids that we consume regularly in our diet. You do get small amounts of short-chain fatty acids consumed from dietary sources, but the majority of them are actually produced in the gut. So, everybody has a gut microbiome, which essentially the term gut microbiome really is just talking about the fact that your gut is inhabited by bacteria. And a really interesting angle that's been coming out of nutrition research in recent years is understanding how what the gut microbiome produces affects health. And so short-chain fatty acids are part of that story.

So, when you consume dietary fibre, dietary fibre can exist as soluble or insoluble, and insoluble fibre is what we have become very familiar with over the years. It's things like cellulose that pass through the gastrointestinal tract intact, and they're really important, and there's been public health drives around increasing fibre intake. And that's related to production of faeces and removal of waste from the body. So, that type of insoluble fibre is very important for our gut health.

But soluble fibre is important for quite a different reason. So, soluble fibre is partially or completely digested once it gets to the large intestine where all of this bacteria resides. And it's broken down into smaller components, so things like short chain fatty acids, and those fatty acids can then move back into the bloodstream. So, some will be absorbed in the bowel, some will be picked up and taken out of the bloodstream in the liver. But some types of those short-chain fatty acids, particularly acetate, they can move through the bloodstream and then end up in any organ throughout the body. And what the recent data has shown is that those short-chain fatty acids, particularly acetate, will end up in the lungs. And in the lungs, they can have beneficial effects around reducing inflammation. They have quite the opposite effect to some of those long-chain fats. They actually have anti-inflammatory actions.

Michelle: And do they have a role in that immunity receptor story that you mentioned before about the saturated fats? 

Lisa: Yeah. So, they have multiple actions. And, yes, one of them is to bind to receptors, a different receptor to what long-chain saturated fats bind to, a different receptor, but still they can operate through that pathway because that's really how our immune system operates. It's based on immune cells having receptors that detect different types of molecules and sense them as being good or bad and then responding accordingly. So, those short-chain fatty acids bind to different receptors, that they actually signal a positive response and production of anti-inflammatory compounds.

Michelle: So, what we eat obviously and the amount of saturated fat that we're eating, the amount of, I guess, simple starches as in glucose and fibre is really important. What is the role of things like exogenous probiotics or prebiotics in this story of immunity and inflammation and lung health?

Lisa: Yeah, and we don't really have a good answer to that yet. So, in the early days of that field of people consuming probiotics, there was a lot of poor-quality products that were on the market that actually didn't provide any benefit at all because, by the time they reached the large intestine, they had been destroyed, the proteins denatured, the bacteria destroyed because of the digestion process. But there are a lot of probiotics now, the field has really developed, and they're being manufactured in a much more suitable way so that they actually are coated and survive the transport through the stomach and the small intestine, and arrive in the bowel intact.

But having said that, there's still not a huge amount of evidence to say that they are actually providing benefit. So, it's really mixed. Some people would really advocate for the use of probiotics. Others would say they're not particularly useful. and the scientific literature is really quite mixed. What there seems to be more strong support for is prebiotics. So, a prebiotic is something that actually is converted into beneficial products once it arrives in the large intestine.

So, we've done some work with one type of prebiotic, which is inulin and inulin is a type of soluble fibre. And most soluble fibres are prebiotics. They are digested, they make their way through to the large intestine, and then they're broken down to produce these beneficial compounds like short-chain fatty acids. But they also, and a really important feature of a prebiotic is that, once it reaches the large intestine, it changes the composition of the bacteria in the large intestines, so they promote the growth of beneficial bacteria and they can suppress the growth of unhelpful bacteria. And so they have a dual benefit of improving the gut microbiome profile, but they're also being a fuel for the production of these beneficial compounds.

Michelle: And what about things like essential fats like omega-3, and omega-6s, and GLA using in things like asthma? What's the research telling us about that? Because I know historically in the naturopathic world and integrative medicine world, we've often used a lot of omega-3s and used those oils in a particularly anti-inflammatory way.

Lisa: Yeah. So, it's really interesting. So, omega-3 fatty acids, I guess, as starting point, I'd say it absolutely wouldn't be damaging for you to use omega-3 fatty acids and certainly there's some diseases and conditions where there's a lot of evidence for benefit to the point where there's recommended intake, so for cardiovascular disease, for example. Rheumatoid arthritis, there's also quite a lot of strong supportive evidence. So, they're definitely not a negative thing. And for anyone taking omega-3 fatty acids, they're quite likely to be beneficial on some level because of their anti-inflammatory properties.

But if you're asking about specific evidence in asthma, there really isn't a lot there yet, so there's been some systematic reviews, Cochrane reviews, that have looked at omega-3 fatty acids and haven't been able to say that there's conclusive benefit from using omega-3 fatty acids, but at the same time, they can't say that they're definitely not helpful. It really comes down to there hasn't been enough research to test that question properly. So, my advice would be we can't recommend it as a definite approach to improve disease, but quite likely that may come in the future.

Michelle: Okay. Well, that's something to look out for. 

And there's a bit of talk around the lung biome and other biomes like the vaginal biome, and skin biome, and all of these other kind of biomes to kind of create this holistic picture. What is your opinion about the lung biome and the gut biome and how they influence each other or what's the latest there?

Lisa: So, my view on the literature is they don't necessarily talk to each other at all, and that's not necessarily a bad thing or a good thing. The lung biome, in people with respiratory disease, it's very much influenced by not just exposures but also medications that people are using. What I think is the most interesting development in this area is the way that the gut microbiome influences activities in the lung. 

So, there's a link between gut disease and lung disease. And so, for example, people with COPD and very significant lung disease have a higher prevalence of inflammatory bowel disease. And there's lots of different bits of evidence that link lung disease and gut disease. What I think is really interesting is how you can modulate the gut microbiome to influence lung disease. So, again, there's evidence to say that - but mostly from mouse models at the moment, not a lot of human work, mostly from mouse models - that shows that if you change the gut microbiome, then you can affect the disease outcomes for COPD.

And we've actually got a large NHMRC Synergy Grant at the moment where we're looking at this exact question to understand that process in humans and to test some of the different strategies that might be relevant in humans. And it's quite likely that, in asthma, there'll be similar sort of ability to influence asthma by manipulating the gut microbiome. But it's very early phases for those studies now, and we don't really understand very well how you might influence the gut biome and then what would be the best strategy for disease management. But that evidence is starting to come out. It's a really interesting field.

Michelle: Yeah. And what about things like pollution? Because often we talk, when we're talking asthma, about minimising air pollution. We know that that's a significant factor if you live near a major road or there’s chlorinated pools and the impact of that. So, do we need to consider that from your understanding of the role of, I guess, holistic nutritional health because of the impact? Is that affecting nutrition, or is it a toxin on its own, or do we know the relationship there?

Lisa: Yeah. So, no, look, definitely. Definitely air pollution is a really important trigger of airways disease as you would expect because you breathe in air pollution and the first site at which it enters the body is the lungs. And so it does trigger and exacerbate any lung problems that a person already has. There's lots of data around showing areas that have high levels of air pollution, asthma is worse. People's chances of having an asthma attack are worsened, and those effects are even more important in children.

In Australia, we're very fortunate that we don't have very high levels of air pollution. And so for that reason, a lot of the work where this has been shown comes from heavily populated cities in the U.S. and we just don't have the levels of air pollution that they have, but it certainly is important for people in specific situations. In Australia as a population, we don't have high levels of exposure, but if people would be living on main roads, for example, then they may be impacted, and so it's certainly something to consider that environmental influence. It certainly does worsen people's airways disease. 

And there's a bit of evidence that's been generated that shows that by improving nutrition, that can provide a strategy to protect against the damaging effects of air pollution. So, high antioxidant diets, high fruit and vegetable diets have been shown to be protective. So, that certainly is, if someone's in... I mean, because sometimes effects of the environment aren't necessarily within an individual's control to eliminate that potential exposure. So, having a dietary approach to protecting against the problem is really helpful.

Michelle: Absolutely. It's so empowering too because often it feels a bit disempowering when you've got so much pollution that's out of your control, and so it's nice to kind of be able to switch the locus of influence back to oneself. And with the hygiene hypothesis, which has obviously been alive and well for a long time, is that still something that we really consider in terms of long-term asthma risk or incidents? Or have we moved on from the hygiene hypothesis, per se?

Lisa: So the hygiene hypothesis, I think we've not necessarily moved on from it, but I think we've evolved our thinking. So, really what we're talking about with the hygiene hypothesis, I think we understand now that one of the really important aspects or why the hygiene hypothesis might be relevant for health, it comes back to this idea about microbiomes and healthy bacteria and avoiding situations where you are eliminating healthy bacteria from the body. So, I think that is more the focus now rather than worrying about people being clean and healthy. The focus has shifted to more around maintaining the integrity of bacteria that are naturally present in the body. And not even just maintain the integrity but...

Michelle: Honouring them and respecting them.

Lisa: ...but if possible, promoting it.

Michelle: Exactly.

Lisa: Yeah, and promoting it. Yeah.

Michelle: I mean, it's kind of a completely different way of thinking because we used to be so antibacterial really with chlorine and cleaning products, and antiseptics, and antibiotics, etc. so having a bit more of a respect for it.

Lisa: Yeah, and really changing our attitude around bacteria. So, when the hygiene hypothesis was generated some 20 plus years ago, we just did not understand bacteria in the way we knew that there was something going on, that if we wipe out bacteria, it can actually make a disease like asthma worse. But at that point in time, we didn't really understand why. But now, as you say, having this healthy respect for bacteria and the role that it plays in homoeostasis of the human body, I think that that's really the focus now.

Michelle: Yeah, and it comes into... I mean, I love the fact that nutrition I think it almost, in the gut biome, allows us to look holistically at everything to understand how the dots all interconnect. 

And I think another area of holism is exercise obviously, and you've got a particular interest in that in your work. Tell us, because you study elite athletes in some regard, what do we understand about exercise particularly for asthma sufferers and disease modification? Is this first-line treatment for asthma? I mean, what do we need to know in terms of an exercise prescription as practitioners? What's the latest?

Lisa: Well, so for asthma, I think probably one of the most important messages is that people with asthma can exercise safely. A lot of people with asthma are concerned about exercising because they might get exercise-induced bronchoconstriction. So, another way of saying that is that some people with asthma when they exercise, that can induce an asthma attack, but that can be managed by pre-medicating with Ventolin. So, Ventolin is used to relax the airways, so when somebody does exercise, it doesn't cause the airways to become restricted. So, that's one important message that you can manage your asthma and be able to exercise. 

In terms of whether or not it's a treatment for asthma, I think that's probably going a little bit too far with the knowledge that we currently have. So, yes, you can exercise safely, but then how could it improve your asthma? There's a growing body of evidence that says that moderate exercise can reduce airway inflammation.

So, there's a particular type of cell in the lungs called an eosinophil, and those cells have been very strongly linked to causing inflammation in the lungs that worsens asthma. But there's evidence now that shows that moderate exercise can reduce those cells, and so you're less susceptible to inflammation. If you go too far, vigorous intense exercise, it seems to have the opposite effect. So, there's a window of moderate-intensity exercise where you get benefit, but if you increase intensity, it actually has a negative effect. So, this is all fairly new information and we're refining our understanding of exercise. But, yeah, certainly light to moderate exercise is only going to be beneficial. And then, yeah, we're still really trying to understand at what point people need to take care because it would worsen their asthma.

Michelle: Yeah, or act as a stressor, which then impacts asthma risk. 

So, reading your research, I was fascinated by your intention into treatment-resistant asthma, which is obviously a big problem and particularly kind of frightening for people that have got treatment-resistant asthma. For example, what's the role of nutrition in the relationship to the effectiveness or ineffectiveness of, say, Ventolin? And then I've got a couple... I'm really excited about this. Yeah, so tell us about that.

Lisa: So, the strongest data that we've got that shows an interdependence of medications and nutrition, the strongest data we have is in relation to the saturated fat. So, the study I described before where we gave people the high saturated fat meal and then monitored their airways for four hours. I mentioned the effect on inflammation, but it also had an effect on people's response to their Ventolin. So, Ventolin is a bronchodilator. As we've just discussed, it's used to prevent exercise-induced asthma but it's also used just in everyday situations where people feel their airways are constricting. Ventolin is used as a very quick-acting relief therapy that's able to relax the airways. And so that's really important as a tool for people with asthma to use their Ventolin and get that immediate relief.

So, our study where we gave people the high fat meal, their Ventolin worked initially, but it wore off very quickly. So, Ventolin should last for four to six hours, the effects of the Ventolin. But when people had a higher saturated fat meal, it wore off after a couple of hours and so...

Michelle: That's so interesting.

Lisa: ...that's really problematic because it means that people are having less protection against that acute episode that they might be experiencing.

Michelle: Yeah, that's right.

Lisa: So, that's really important advice that we've been promoting to people with asthma to, if you're in a situation where you need your Ventolin, then avoiding high doses of saturated fat is a really important strategy.

Michelle: And what about the impact of obesity and on steroid-resistant asthma? I know that you've got some research on actual body habitus and body fat.

Lisa: Yeah. Obesity complicates the management of asthma. So, if you're obese, then it means that you're more likely to have worse symptoms. You're more likely to have an asthma attack. Medications don't work as effectively. Quality of life is decreased because your asthma is really worse in every way. And so it's really problematic. And the other thing is, if you're obese, you're more likely to have steroid-resistant asthma. So, steroids are the way that asthma is usually managed, and the mainstay of asthma therapy is corticosteroids, so they might be inhaled corticosteroids. So, people use a puffer of inhaled corticosteroids, or in worse cases, more severe cases, people might use oral corticosteroids, but they are the main form of treatment for asthma.

If you're obese, then that tends to make steroids less effective. So, that's important information. And so some people would just say, "Well, that's easy. We know the solution to obesity. You just get people to lose weight. And if people do lose weight, then their asthma does improve." But we also know that it's not that simple to just tell people to lose weight. So, we are working on strategies, different types of medications that might be able to be used to help manage obese people better. And it's not very well developed at this stage. A lot of work's being done to try and come up with better medications that can be used to manage obesity.

And we're also running a trial in our centre at the moment where we're trying to come up with lifestyle strategies that can also help. So, assisting people in their weight loss journey, tailoring weight loss strategies, tailoring exercise strategies, so that there's a package of tools that people can use that are tailored to their own individual needs and their preferences that will enable them to be successful with their weight loss.

So, we haven't given up on that as a strategy. We do think that's an ideal strategy to actually manage the problem of obesity rather than just using another medication. And that, of course has benefits, not just for their asthma but also for a range of...

Michelle: Cardiovascular disease, etc.

Lisa: ...diseases. Yeah. So, we haven't given on that as a strategy, but, yeah, there's a lot of work to be done there.

Michelle: Yes, a big challenging area, isn't it? 

I know that actually you dig down deeply into the role of obesity, and the role of the adipocytes, and the role of the inflammation. What do we need to know as practitioners in that realm to help us really understand the pathophysiology of obesity and how that relates to asthma?

Lisa: Well, we've been trying to understand the physiological effects of obesity. So, there's a bit of an attitude at the moment that people who are obese should embrace their bodies and love their bodies, and they absolutely should. But what we've been focusing on in the lab is really understanding it's not just about appearances. It's about what's actually happening to the body when somebody is obese. So, when somebody gains weight, the adipose tissue that is there to store fat, it changes its function. So, it's not just a fat storage tissue, it turns into a very inflammatory tissue. So, the adipocytes become engorged with triglycerides, and they reach a tipping point where that actually sends danger signals, and cells start moving, inflammatory cells, immune cells start to move into that tissue. They become active and start releasing these inflammatory mediators.

And because obesity isn't a passing thing, it's there day in, day out, week in, week out, year in, year out, that chronic release of inflammatory mediators from the adipose tissue starts to damage different organs in the body. So, it does contribute to just about every chronic lifestyle disease that you can think of. It's worsened because adipose tissue is promoting the production of these inflammatory mediators, which then damage the different organs.

So, I think that it's really important to remember, when you said advice as practitioners, I think it's really important to remember that obesity is a very complex condition, and there's psychological aspects to it, but there's also physiological aspects of obesity that we can't forget about. And so we need to keep pushing for people to try and reach and maintain a healthy weight because that will prevent these secondary effects of obesity where you start developing diseases such as cardiovascular disease, diabetes, but also something like asthma.

Michelle: Yeah, it's fascinating because we often miss out on that lung component, don't we? 

And you started out your research career looking at cystic fibrosis. And obviously you found there was a connection between nutrition, and that's a really unique disease with a really interesting kind of lung and gut interface and then you moved on to asthma. But you mentioned a little bit about COPD. Is there other things about like... Because in general practice, we see a lot of chronic lung, chronic bronchitis, COPD, emphysema or even a mixture of all of that. How are you extrapolating that information in terms of overall or holistic lung health to conditions such as that? And are we moving into that space? 

Lisa: Yeah. So, well, once they're all different diseases, which you list there, they all have a similarity in the underlying pathology. So, they all involve inflammation, and you can even extend it beyond those lung diseases because not just those diseases that you've mentioned, but also things like cardiovascular disease, diabetes, some cancers, they all have this underlying inflammatory pathology.

So, the dietary strategies that we've been studying in asthma, essentially they're generalised approaches to reducing inflammation in the body. And the source of the inflammation might be different. So, obesity is a source of inflammation but so is exposure to air pollution. So, they're two different triggers, but they are all causing inflammation. And so the key strategies that we've been able to identify for asthma are increasing fruit and vegetable intake which gives you a high antioxidant intake, a high fibre intake, also avoidance of higher saturated fat foods. They're some of the key strategies we've identified for asthma, but they all target inflammation and so they're all strategies that are relevant to those other lung diseases that you mentioned as well as other lifestyle diseases such as cardiovascular diseases and diabetes.

So, none of the strategies are really sort of earth-shattering, "Oh, gee, I didn't know fruit and vegetables were good for me," but what we've been doing is really gathering the evidence to say, "Well, yes, but did you know that they're not just good for you as a generalised approach to eating? They're actually specific mechanisms by which they will help you manage your asthma." And that's really what we've been doing, not identifying things that are earth-shattering and new, but linking those strategies to disease management in asthma so that people can understand and be motivated to make those changes to their diet. And COPD certainly, there's a lot of evidence around COPD and using those strategies in COPD once again to reduce the lung inflammation.

Michelle: Mm, absolutely. It's such an exciting space, and I think, as much as you say, it's not like we didn't know the power of fruit and vegetables prior to your research but more actually creating the narrative and the story so that practitioners can really support their patients in delivering that message early on in their asthma journey.

Lisa: Yeah, and prioritise it too.

Michelle: ...or early on in... That's right.

Lisa: Yeah, because, I mean...

Michelle: Emphasise it, prioritise it, really make it a very important message.

Lisa: And most practitioners that are seeing these patients, they've got multiple problems, and there's only a limited window of time to actually spend with them to talk about strategies to manage their health. But what we're really hoping is that people will see this evidence and say, "Okay, well, I do make a chance to talk about my patient's weight problem, or we do need to make a chance to talk about what are you eating, are you eating enough fruit and vegetables," because it's not just something that should be pushed aside. It really is. It should be very central to managing their health.

Michelle: Yeah, absolutely. Oh, what a wonderful message. Thank you so much, Professor Lisa Wood, for coming on the show today and discussing lifestyle medicine and lung health and really not only the opportunities for treatment, but prevention and how everything interconnects. And I think from a practitioner's perspective, some of your research has really, I guess, embedded the confidence to really promote and emphasise and push forward the narrative of how important lifestyle is for chronic lung conditions and what a difference it can make.

So, I know that you're doing the most amazing work in this space, and it's so important, and very appreciative as a community. So, thank you so much for coming on the show.

Lisa: Thanks for having me.

Michelle: Thank you, everyone, for listening today. Don't forget that you can find all the show notes, transcripts, and other resources from today's episode on the FX Medicine website. I'm Dr. Michelle Woolhouse and thanks for joining us. We'll see you next time.


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