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This is The Guardian. Redness, pain, swelling. Acute inflammation is what our bodies do naturally to fight infection. But there's a darker side to this natural response. We now know more than ever about how our modern Lifestyles, from what we eat, how much we sleep, and the pollution in our air, contribute to chronic inflammation, which is linked to an increased risk of many diseases.

From cancer to cardiovascular disease, neurodegenerative disorders, musculoskeletal conditions, metabolic disorders, and the list goes on and on.

And rates of these diseases are only set to increase, which is why this relatively new field of science could hold the key to helping us all live longer and, crucially, healthier lives.

So, as we get older, many doctors will tell you, you should slow down because there's wear and tear. What we want is actually quite the opposite.

So what do we need to know about the causes of chronic inflammation? And how can we reduce and even reverse its impact? I'm the Guardian's Science Editor Ian Sample and this is Science Weekly.

Yeah, near to the church in the countryside, it's beautiful, but sometimes…

It sounds wonderful. Dr David Fuhrman is director of the 1000 Immunomes Project at Stanford University School of Medicine and an associate professor at the Buck Institute for Research on Ageing. But when we spoke, he was in sunny France. Are you working in France at the moment or are you on holiday?

I don't really know the distinction between the 2. I live in a very pleasant environment by the beach in San Francisco. For me that's year-round vacation but I work every day. This is no different from that. We're enjoying the south of France and I'm working remotely.

I have 2 groups and I have 2 startup companies. I'm also a founder of the National Inflammation Institute. So a lot of things going on, I can't stop working, I can't afford that.

It's safe to say he's been pretty busy.

I've been measuring my inflammatory age for quite a number of years now. And yes, over the past 3 to 4 years, by taking more and more responsibilities, inflammatory levels have rised. So you're absolutely right.

We'll come back to why all this work on inflammation is raising David's own levels later. But I wanted to start by asking what exactly inflammation is.

The inflammatory response is a mechanism for the body to react to foreign entities, and namely infections. It really helps the whole immune system to react to foreign bodies and clear up those infectious agents and in a normal setting that should go back to baseline in about say 3 to 7 days.

Okay so that's acute inflammation but you're focused on something different So tell me about that and what it might be doing to us.

The inflammation that I am mostly focused on is rather the age-associated inflammation, which is sustained over time. It causes collateral damage in tissues and organs, increasing the likelihood of developing the most nasty, very feared diseases of aging. We're talking about cardiovascular disease, so high levels of systemic chronic inflammation increases the risk of heart attack. Metabolic disorders that include type 2 diabetes and metabolic syndrome. Musculoskeletal conditions, namely bone joint ailments.

We have osteoporosis, it's largely driven by systemic chronic inflammation. Cancer, so cancer cells, they need inflammation to actually replicate and metastasize. We have a whole program in Alzheimer's disease and dementia and we've seen that circulation of inflammatory biomarkers increases the risk of developing early brain atrophy and cognitive impairment. So the list is really extensive and it covers all sorts of organs and systems.

So clearly the science is suggesting this chronic inflammation is playing a really significant role in our overall health. And we'd expect to see a degree of increased inflammation as we age, wouldn't we? So, is inflammation accelerating the aging process in our bodies?

That's exactly right. It defines rates of ageing in different organs. This idea was put forward by Claudio Franceschi in the University of Bologna in early

2000.

Before then, we had no clue that inflammation leads the way in defining rates of aging and increasing likelihood of diseases. This is a rather new field.

So should I think of that chronic inflammation as a sort of low-grade but heightened response that's ongoing from the immune system. And if I've got that right, what is the mechanism? What's it actually doing to our organs and tissues?

The definition is correct. It's typically low grade. This means that it's not like the acute response where the biomarkers increase significantly in the tissue, but rather this is a very mild increase but sustained elevation in some of the biomarkers or the leading proteins that increase in its expression in blood, they go in the tissues and disrupt tissue function. It's very clear how some of these proteins are associated with cellular senescence, for example, in tissues, which is a largely dysfunctional state of these cells. It could be endothelial cells that will cause ultimately issues in the vascular system, but also some of these biomarkers cross the blood-brain barrier and they go to the brain and they actually disrupt function in the brain and it can also cause cellular death.

And so these are associated with Alzheimer's disease in those cases, for example.

So we've talked about how this inflammation becomes a problem when it's long term, but I'm interested in what leads to chronic inflammation. Are there triggers in adulthood, can factors in childhood matter too?

Bottom line, what we're experiencing here is a distance from our evolutionary experience. We have evolved in a very particular environment. Now Any species that you move to a new environment by definition will develop inflammation. And that's exactly the case of humans as well. There are a number of chronic stressors that will ultimately cause systemic chronic inflammation in the body because the mechanisms that we have to cope with inflammation and to bring it back to baseline are not in place because of this sustained chronic social stress.

In terms of the rest of the lifestyle triggers, we can talk about plasticizers that are leaching from plastics, pesticides, jet lag, lack of a good quality sleep that restructs your chronobiology and the immune system is very well aligned with the circadian rhythm. And so if we have time shift workers or time zone changes, we're disrupting the circadian rhythm and that increases our levels of systemic chronic inflammation. The other very important 1 is what we eat. For example, we haven't evolved with wheat or, say, flour-derived products and this causes inflammation at the level of the gut.

You talked earlier, David, about social stressors. I wondered if you could unpack that phrase. What sorts of things count as social stressors which can raise this risk of having chronic inflammation?

So the list is also very long. I can give you a few examples here of social stressors. The fact that we're comparing ourselves with all these influencers and rock stars and people want to be as famous as those individuals. This is a level of chronic stress that you're comparing yourself with someone you'll never be able to be. We're also exposed to a very high load of our work times, right?

So now we're going to occupational stress. There are very good papers, examples of experiments where we've seen caregivers of cancer patients, which are a really good example of social stress because they're taking care of a cancer patient is not an easy task. And we've seen that in cells from these individuals, there's major inflammatory biomarkers, very high. When you try to bring that inflammatory response down with say, classical drugs, You cannot. So this is a classical example where you have a social stressor.

You're basically feeling psychologically stressed. And the consequences for the body in terms of systemic chronic inflammation are very clear and very detrimental. Do

we tend to see different levels of systemic chronic inflammation across the classic divides we see in sort of inequality, is there more chronic inflammation among people in poverty, among people with lower socio-economic status for example?

Great call. Not just low socio-economic status but discrimination, inequality. This is very clear. We've seen a number of reports where, for example, in the US, African American communities have a much higher level of systemic chronic inflammation that Caucasians do, for example, or Latinos, it's very clear how they're in the similar, say, socioeconomic status. Even then, because there is inequality given by ethnicity and other aspects of this, they are more exposed to systemic chronic inflammation.

They're chronically stressed, and that increases the likelihood of developing the diseases that we mentioned. And that's how we explain the epidemiologic results looking at Latinos, African-Americans, as compared to white people.

David, I want to get on to sort of what we might be able to do about this. But first of all, are there tests that can detect whether people have systemic chronic inflammation and whether it's at a problematic level? I presume we all have it to some extent.

In the US, across the populations that we've studied, around 80% of people over 40 years old are inflamed. We can measure those responses by taking a blood sample and running that blood sample through a battery of tests that we identified using the Stanford 1, 000 Immunums Project. So Can we measure systemic chronic inflammation? Yes, we can measure this and it's a relatively new test that will probably be in the marketplace in 6 months to a year from now.

David, a lot of the sort of driving forces for this chronic inflammation that you've talked about really feel like they're products of industrialization in a sense. And I wondered if, given that we're probably not going to reverse industrialization, that kind of urbanization and what have you, What are the options out there? I mean, are there treatments?

There are really 3 major aspects. 1 is protecting ourselves from the exposome. The second is challenge ourselves. And the third 1 is repair. So starting from protection, we have a long list of things I mentioned, maybe cutting on flour and other weed derived products, be protected from pesticides, try to eat as much organic food as possible.

Fish is in particular rich for omega-3 polyunsaturated fatty acids, and these have anti-inflammatory effects. We would like to cut on omega-6 polyunsaturated fatty acids which are largely inflammatory and they're found in eggs, avocado. We also want to nourish our microbiome. We didn't talk about that, but I can give you an example. Polysorbate

80,

which is found in most cosmetics and foods out there, it's basically a emulsifier that enables mixing oils with water, for example, right? And those have nasty effects for your microbiome. You want to avoid that kind of thing and hopefully be able to feed your microbiome with probiotics, for example, high content of soluble fiber. Intermittent fasting is a very powerful tool that we can all practice and I do that every day. So for example, my last meal of the day would be 6.30 to 7pm and my first meal will be around 1.30pm and we know this has major consequences in improving your inflammatory health and being protected from plasticizers as well.

So don't use any plastic containers, but rather you can use metal or you can use wood based or even glass based containers because plasticizers will leach into your food and you'll ultimately be consuming this thing here.

So David I think that's sort of the protect side you were talking about. What sorts of things can people do around the challenge and repair which you mentioned was so important as well.

Challenge basically refers to a number of interventions that will challenge your body mentally and physically. So as we get older, many doctors will tell you, you know, you should slow down because there's wear and tear. What we want is actually quite the opposite. You need muscle mass. Muscles are anti-inflammatory organs that produce more than 300 anti-inflammatory peptides.

You want to have muscle mass as we grow old as much as possible. And then also when you compress your bones by having walking every day or even light jogging, you will be creating more bone. And that's what we want as we get older. Intermittent fasting is the best example of challenge. You're challenging your body, triggering an evolutionarily conserved response that is largely anti-inflammatory, and we have notable effects, including extension of lifespan and healthspan in model organisms.

And the repair side of things, Is that involving things like sleep?

That's a good, yes, I was going to say. So mastering sleep hygiene, we know very clearly that the effect of electrical light, and in particular the blue spectrum, will be interpreted by the body as we're starting the day, right? And the starting the day means there's a number of hormonal changes that go with it. Cortisol is the best example of it. So decreasing electrical light exposure at night, We've seen in a number of papers that meditation lowers systemic chronic inflammation and prepares the body for good quality sleep.

So maybe half an hour, 20 minutes of meditation prior to sleep seems to be beneficial.

David, it seems like there are actually quite a few things people can do, quite a few steps they can take to try and keep this kind of chronic inflammation in check. But it makes me wonder whether doctors and the health systems that they work in have really embraced this. Is this sort of knowledge and advice embedded in medicine already?

Not yet and this is a really good point. They must catch up, right? There's typically about 15 to 20 years lag from discovery in the academic setting until it reaches the public. The other large effort that we have been now focusing on is the National Inflammaging Institute, which has that mission to disseminate this knowledge and make it available to the masses, to the public, including obviously healthcare providers, and be able to lower systemic chronic inflammation in the population around the world, hopefully.

David, it's great to have you on. Thanks so much.

Thank you so much, Ian. Thank you for having me.

Thanks again to Dr. David Furman. Before you go, you need to know about Guardian Jobs, our job platform that connects you with like-minded people to build rewarding careers. Flexibility, values, salary, find a workplace that ticks all your boxes. With high-quality roles in sustainability, government, social care, charity and education, you'll be spoiled for choice.

Search Guardian Jobs to find your next role. And that's all from us. The producers were Josh Anchana and Ned Carter-Miles. The sound design was by Tony Onuchukwu. And the executive producer is Ellie Burie.

We'll be back on Tuesday. See you then. This is the Guardian.