How to reverse arthritis in 8 weeks with Dr. Tamiko Katsumoto

Arthritis affects millions worldwide. One in 5 adults in the U.S. experiences it, yet many people assume it’s an inevitable part of aging. What if you could reduce joint pain and inflammation through diet and lifestyle?

In this episode, Dr. Tamiko Katsumoto, Clinical Associate Professor at Stanford University, unpacks the science behind arthritis.

She explains the key differences between osteoarthritis, caused by wear and tear on joints, and rheumatoid arthritis, an autoimmune condition where the immune system attacks healthy tissue.

While there is no cure for arthritis, Tamiko reveals why chronic inflammation plays a central role and how the modern diet is making things worse.

If you or someone you know has joint pain, this episode is packed with insights to help you take control of your health.

Make smarter food choices. Become a member at zoe.com - 10% off with code PODCAST

Try our new plant-based wholefood supplement - Daily 30+

*Naturally high in copper which contributes to normal energy-yielding metabolism and the normal function of the immune system

Follow ZOE on Instagram.

Transcript

Jonathan Wolf: Tamiko, thank you so much for joining me today. 

Tamiko Katsumoto: Thank you for having me. Excited to be here. 

Jonathan Wolf: I think it's going to be a lot of fun. And right at the start, I think you know, because you told me you're a regular listener yourself, we have a tradition here at ZOE, where we always start with a quick-fire round of questions.

Are you willing to give it a go? 

Tamiko Katsumoto: Absolutely. 

Jonathan Wolf: All right. So remember, yes or no, or if you absolutely have to, a one-sentence answer. Are more people developing arthritis? 

Tamiko Katsumoto: Yes. 

Jonathan Wolf: Does the food we eat play an important role in arthritis? 

Tamiko Katsumoto: Yes. 

Jonathan Wolf: If you're starting to feel symptoms, is full-blown arthritis inevitable?

Tamiko Katsumoto: Not necessarily. 

Jonathan Wolf: Could you reverse arthritis with the right foods? 

Tamiko Katsumoto: Yes. 

Jonathan Wolf: And finally, and you have a whole sentence, Tamiko, what's the biggest myth when it comes to treating arthritis? 

Tamiko Katsumoto: I think the biggest myth is that there's nothing you can do to change your arthritis course. I think there are actually a lot of things that we are all capable of doing through diet, lifestyle, et cetera, that can make a difference.

Jonathan Wolf: Now, when I was growing up, everyone talked about tobacco as the leading cause of chronic disease. And today we're sitting here and we're basically talking about poor nutrition as the biggest cause of this. 

It's been eight years since I co-founded ZOE and I think every year I've just got more and more shocked at the way in which the food that we're eating across the Western world is making us so sick. But also just discovering each year about ways in which it affects us that I had no idea about. 

So today we're talking to you as a professor of immunology and rheumatology at Stanford about arthritis and how it's linked to food. I never would have guessed when I founded ZOE, that it could have anything to do with food. In fact, I would have said that was crazy, totally non-scientific. So it's amazing how much I think my understanding has changed. 

What is arthritis and how does that relate to this concept of inflammation, which I know is a lot about what you study.

Tamiko Katsumoto: You and me both. I think we in medical school were not taught about the role that diet and all these other lifestyle factors play in a lot of our inflammatory diseases. 

I'm a rheumatologist, so I take care of patients with arthritis with a lot of other inflammation of other organs. So rheumatoid arthritis, lupus, vasculitis, you know, psoriatic arthritis, you name it.

I think arthritis is complex. Basically, our joints are generally protected areas where you've got your bone, you've got a synovial lining, you've got this nice joint capsule that is lubricated so that it allows us to move freely. 

The problem is with inflammation, there can actually be a breach of those protective barriers such that you can end up getting inflammation.

There's actually a connection with the gut and mucosal barriers that play into the inflammation, leading to arthritis.

Jonathan Wolf: Tamiko. I know nothing about how my joints work and I could see you're sort of painting a picture of something quite mechanical with some oil running. Is that the right analogy? Is that what you described, just help me to understand a bit.

Tamiko Katsumoto: Yeah, I think that there's a lot of analogies. We talk a lot, I know ZOE talks a lot about the gut and how there's this important lining of the gut. 

Similarly, I think you can think about the joint, in that there's an important lining called the synovial lining of the joint that can get breached when you end up having, let's say, T cells that are recognizing some of the synovial proteins, so the joint proteins. 

There can actually be what's called an autoimmune attack where your own T cells can end up invading the joint causing inflammation. It causes a leaky joint, if you will. We've heard about leaky gut. 

I think what we've started to learn over the course of many years of research is that these mucosal breaches, for example, in our gut, even in our mouth or oral microbiome, can stimulate certain bacteria that may actually cause our immune system to wake up. T cells that are attacking these specific bugs in our gut, in our mouth can end up actually getting confused and attacking our joints. 

So this is a whole hypothesis that's coming to fruition with some very exciting science recently in terms of how our immune system can be connected to joint inflammation.

Jonathan Wolf: If I understand rightly, what you are saying is, I'm not experiencing any arthritis today, so I can sort of move all my joints around and they're able to sort of slide around somehow really smoothly. I'm thinking a bit like a sort of Teflon pan or something like that. 

But you're saying that what can happen is my own immune system ends up attacking parts of these joints and breaking that Teflon. And then suddenly, It's both painful and does not move as smoothly. Exactly. I don't know if I'm stretching this analogy way too far. 

Tamiko Katsumoto: No, it's a great one. I think that it's either immune attack that can lead to the disruption of this nice synovial barrier that can lead to arthritis. My patients end up getting very swollen, tender, red, hot, painful, stiff joints.

Other ways that this can happen are through damaged responses. So one thing that a lot of people may have heard about is a condition called gout, and that would be a crystal. There's a crystal called uric acid, which is a byproduct of a lot of cellular metabolism. And those uric acid crystals can end up building up in our joints. And that can end up triggering this inflammatory response as well. 

So I think that there are different paths leading to arthritis. What we call the acute inflammatory innate response, and then there's a more complex autoimmune mechanism that we were talking about, when you have T cells that are attacking the joints.

So there's various ways in which arthritis can develop and we can talk a little bit more about kind of what are the things that set you up for that. 

Jonathan Wolf: How many people are affected by this? 

Tamiko Katsumoto: So, it's estimated that about 1-2 % of our population is affected by rheumatoid arthritis. The numbers for osteoarthritis are much higher in the millions. Psoriatic arthritis, a little less common.

But again, I think the important point to note is a lot of these autoimmune,, inflammatory diseases are on the rise. You know, lupus, for example, is an autoimmune condition that can affect multiple organs, certainly the joints, often the kidneys. And one of the lab tests that we use is called an ANA, which is an anti-nuclear antibody.

If you look over time, actually those numbers are going up. So now, in terms of females, actually up to 20 % or more of females will have a positive ANA. So there's this increasing incidence of autoimmunity that we're seeing in general. 

I think one of the key questions is why is that happening? What's driving this? I think a key point to make here is that we are not evolving that quickly. Our genetics are not changing. 

I think what this speaks to is the importance of epigenetics, meaning environmental influences that are changing how these diseases are manifesting. So clearly I think there's a lot of environmental drivers that are leading to this increased prevalence of arthritis and other chronic inflammatory diseases.

Jonathan Wolf: I'd love to get into that. Just before we do that, I was just thinking about my grandmother. So my grandmother had really quite severe arthritis, and she refused to ever complain about it. So it was quite obvious that she was in pain, but she was of that generation that like, you should never make a fuss.

And actually, interestingly, her mother had very severe arthritis as well. So I assume that there is a genetic component in this. 

Tamiko Katsumoto: So yes, in rheumatoid arthritis, there's something, I'm going to use a fun term here, called a shared epitope. There's a specific gene that has been linked clearly to rheumatoid arthritis.

There are other types of arthritis, there's one called ankylosing spondylitis, where it tends to affect the back and also the sacroiliac joints and some of the larger joints. This is one of the arthritis types that's more common in males. 

There's a genetic predisposition there, which is called HLA B27. Maybe some of you have heard about this. To be honest, when we think about the genetics, I think that, relatively speaking, that plays a less contributory role compared to a lot of the environmental factors that are driving arthritis. 

Jonathan Wolf: Got it. And so what is the experience of someone who's living with arthritis?

I know you've mentioned both osteoarthritis and rheumatoid arthritis. Are they experienced the same or what the difference is? Maybe just help to paint a bit of a picture for people who aren't familiar with this. 

Tamiko Katsumoto: Yeah. So osteoarthritis is, unfortunately, one of the most common types of arthritis, and we used to call it kind of a wear and tear degenerative arthritis, less inflammatory.

These are the types of arthritis that can occur in joints that have previously had, for example, an injury. A lot of athletes that have messed up their knees or their hips, whatever, that can happen. However, I think we're learning osteoarthritis actually might have a more inflammatory component than we previously realized.

It's more common in people that are overweight, it's possibly related in some ways to the fact that they're bearing more weight on those joints, so there may be a mechanical component. 

But there are other components for osteoarthritis we don't fully understand. For example, the hands can be affected by osteoarthritis, and so clearly we're not bearing weight in our hands. Osteoarthritis is one of the classic most common types, it's not considered to be truly inflammatory. 

Rheumatoid arthritis is the most common inflammatory arthritis. Again, I think that we are starting to understand that there are genetic contributions, but more and more as we move forward, we're learning the environmental components are substantial.

Jonathan Wolf: What do you experience as a patient living with osteoarthritis or rheumatoid arthritis? 

Tamiko Katsumoto: Osteoarthritis, I'll call it OA, osteoarthritis, tends to be less inflammatory. People tend to get more and more pain with motion, with using their joints. 

In contrast, rheumatoid arthritis is considered inflammatory, meaning that people tend to wake up feeling incredibly stiff takes a while for them to get up and going. They often feel like they need to get their joints moving. A hot shower might really help get them moving. They experience what's called gelling, where you sit down for a prolonged period of time, and your joints kind of gel, and then as you start to move them, that starts to get them feeling better.

But rheumatoid arthritis can be profoundly disabling. The amount of pain, the amount of dysfunction, a lot of patients, for example, if it's affecting your hands, you're not able to open jars or grasp things or using your joints the way you normally would like to. 

It can be very painful in terms of if it affects your foot joints, it feels like you're walking on marbles, or glass in some cases.

Back in the day, this used to be a very debilitating condition and people would often end up disabled in wheelchairs or really unable to perform their jobs or activities of daily living. I think we've made some significant progress in terms of the treatments that are now available.

So I have to say, there's been the advent of disease-modifying agents. We use methotrexate, we use hydroxychloroquine. We also use a lot of these biologic agents that are specifically targeting some of these inflammatory cytokines, which is a fancy word for inflammatory proteins, TNF, tumor necrosis factor, and interleukin 6.

These are some of the inflammatory drivers that lead to the inflammation within the joints. 

Jonathan Wolf: You've slightly scared me with all the terminology, Tamiko, but what I'm understanding is that it's tough to live with this.  It has a big impact on your quality of life. 

Secondly, the good news is you're saying that medication has moved on a lot from, you know, thinking about my grandmother and never mind my great-grandmother. So there is a lot that can be done, but it doesn't just make the whole thing disappear. 

Tamiko Katsumoto: So I think people can really have improved quality of life on these medications, but there's a trade-off and the trade-off is when we suppress your immune system, you are then more vulnerable to infections.

In some cases, we worry about cancers. In some cases, we worry about what is the long-term impact of very directly targeting some of these key inflammatory mediators. So that's the concern. 

Jonathan Wolf: You've talked about inflammation a lot and talked about how not only in rheumatoid arthritis, but you're saying also in osteoarthritis where people said before, there's no inflammation.

You're saying the latest evidence suggests there is. Could you help us to understand in very simple terms, what is inflammation and what's going on that is clearly causing this very significant sort of attack on my own body? 

Tamiko Katsumoto: These are always difficult concepts, very kind of abstract.

I think maybe the best way to distill this would be inflammation can be thought of as a damage repair mechanism. So for example, when we cut ourselves, we need inflammation. We need the white cells to come in and help heal that wound. 

When we have an infection, we need inflammation to come in and actually help fight against these invaders, you know, viral bacterial fungal. But I think that the key problem is that unfortunately, the way our lives have evolved is we are being constantly exposed to these various inflammatory threats. 

Now, one of the biggest ones is our diet, and it's driving inflammation that's aberrant, that shouldn't be happening all the time, and so you can imagine that we end up driving this chronic level of inflammation, these inflammatory cytokines I just talked about, TNF, IL 6, the ones that we target for arthritis. Those are going up and up in response to a lot of the foods that we're eating, a lot of the other environmental insults that we're experiencing. 

Believe it or not, when we talk about arthritis, rheumatoid arthritis, this is a systemic inflammatory response. It's not just in our joints, it's our whole body on fire. 

So really, it's leading to accelerated cardiovascular disease. It's leading to a lot of these other metabolic consequences. I think we see in our patients, a lot of them don't just have arthritis. A lot of them also have diabetes and hypertension and cardiovascular disease and accelerated, you know, a lot of them have memory disorders.

So I don't like to be reductionist and think of arthritis as just one entity. There are so many comorbidities that come with it. And the common theme underlying it all is inflammation. 

Jonathan Wolf: I'm really struck by this image that you just said about our whole body is on fire. And so is that a way, when you're describing someone living with this permanently raised level of inflammation that's on all the time, that's a very strong metaphor. That's a real way to understand what's going on. 

Tamiko Katsumoto: Yes. One of the biomarkers we use is ESR, which is erythrocyte sedimentation rate and C reactive protein. And those are often quite high in these conditions. And I'll give an example.

So the cardiologists have caught onto this and they are using C reactive protein as a marker for risk for cardiovascular disease. 

So our patients have very high levels of these inflammatory markers. And so you can imagine it is driving inflammation in multiple organ systems, not just the joints.

Jonathan Wolf: You're saying that we can measure in our blood all of these different chemicals and you're saying there's a whole bunch of them. I think you mentioned CRP for example, that are ways to tell how high our inflammation is set. 

And this is our immune system going like, wow, this thing is really dangerous, you know, ringing the bell for the fire engine and the police and the army and whatever.

And you're saying that it's really high with people living [with] arthritis, but we now know that that is a sign of a lot of risk for damage to your heart, for example, as well. Because basically when that this thing is so high, somehow your body is no longer… I'm thinking about the mayhem at the end of a Hollywood movie after something's gone wrong, right?

You've got the SWAT teams, everyone, all the rest of it, no one is able to go to work. No one is able to go home. It's all a mess. And that's sort of what's going on in our body when the inflammation doesn't go back to normal after I've cut my finger. 

Tamiko Katsumoto: That is right. 

Jonathan Wolf: So far the picture is a bit bleak, but I know you already talked about how food is an important cause of this problem.

You already mentioned inflammation from food, which I think some people listening will be like, but is that a real thing? And you're saying this is a real absolute thing.

But I understand that you're also really interested in food as playing an important protective role. And that in particular [you’re] excited about a breakthrough new clinical trial that the team was telling me about actually earlier this week, which I think is called plants for joints.

Could you tell me about that? 

Tamiko Katsumoto: And by joints, we're talking about joints, the anatomic joint, not the other kind of joint, I'm from California. 

This was a very exciting trial. I'm a huge fan of randomized controlled trials. I think this is our highest level of evidence. This is a group, our Dutch colleagues, they actually did two studies in parallel.

They did one in rheumatoid arthritis and they did one in osteoarthritis. To clarify, it was a metabolic-associated osteoarthritis. So patients that tended to have metabolic syndrome were maybe overweight. So those patients with OA. 

Jonathan Wolf: And so randomized controlled trials are basically the gold standard of scientific testing?

Tamiko Katsumoto: Yes, they are helpful in that they minimize any confounding bias in terms of the fact that people are put into two different groups, there's an equal chance of whatever intervention working or not, and comparing to a placebo provides a robust comparator. 

Basically what they did was they put them through a lifestyle intervention, and this is absolutely really thrilling to me because I'm a huge fan of the American College of Lifestyle Medicine.

Just to quickly provide their six pillars of lifestyle medicine; diet is number one, in addition; exercise, stress reduction, social connections, sleep, and then finally avoidance of risky substances. So those are the six pillars of lifestyle medicine.

Essentially what this randomized controlled trial did was put these patients through either the active arm. They called it the plants for joints arm that underwent these six lifestyle interventions versus the placebo, which was essentially the standard of care. 

They ran them through this program for 16 weeks and what they found at the end of the study and even at eight weeks at the midpoint, they saw dramatic improvements in the patient's joint disease.

So for the rheumatoid arthritis patient, the endpoint they looked at is called DAS28. This is a disease activity score based on 28 different joints. So you measure swollen and tender joints. You measure the CRP inflammatory marker. You measure how the patient is feeling. 

Based on that endpoint, which is a very robust endpoint, there was a very statistically highly significant difference in terms of the RA patients that underwent this lifestyle program.

They looked more deeply to see what was the most likely thing driving this difference, and it was most likely diet. Of course, you can't separate out, it was a full holistic intervention of multiple different domains. 

But anyway, bottom line, I think diet played a huge role. And what they did was they educated these patients on whole food plant-based diets. So minimizing processed foods, minimizing or mostly eliminating animal products, increasing fiber intake, and really trying to encompass a very healthy whole food diet. The same thing was done for osteoarthritis. 

And the reason I got so excited to see the results for osteoarthritis is we don't have great treatments for OA. It's one of the most common conditions, debilitating, a lot of us get it, and yet we often don't have good answers. And so the fact that this lifestyle intervention showed such a promising result. I think it was really exciting for the field. 

Jonathan Wolf: There was a big impact for both these groups with these different types of arthritis?

Tamiko Katsumoto: Yes. 

Jonathan Wolf: Because I know sometimes scientists can get really excited about something that's statistically significant, but it's a 2 % change. And so the scientists get really excited about it, but as a normal person or patient, that isn't really going to change my life.

Does this actually make any difference to the symptoms and how they were going to feel after this? 

Tamiko Katsumoto: Yes, this was definitely beyond the minimally important clinical difference. So there was clearly an impact on patients' lives and quality of life.

What was most exciting, they did a one-year follow-up of these cohorts and they showed that a lot of these patients were able to get off of their medications. 

Jonathan Wolf: They were able to actually give up their medications because you were talking about how serious this is. So that seems rather amazing.

Tamiko Katsumoto: Which is incredible. I think the, you know, a lot of them ended up gradually, de-prescribing a lot of their meds, a lot of them lost weight, a lot of them improved in terms of their blood pressure in terms of a lot of other cardiovascular, lipid profiles, these types of things.

But I was most struck by the fact that some of them were able to wean off these medications, which was striking. 

Can you help us understand how this change in what you're eating could suddenly stop your joints being inflamed and in pain? Because, you know, the link is not obvious. 

Tamiko Katsumoto: I think it's complex and multifactorial.

Simply speaking, I will say we know a lot of our dietary components, like sugar, a lot of these, saturated fat, and processed foods, drive inflammation in various ways. 

I think one of the primary ways is through how it affects our gut microbiome. I think that we end up assaulting our important gut barrier by loading it with all this sugar and fat and these emulsifiers and food colors and other process things that are really insulting the gut barrier. And that is leading to this systemic inflammation.

A lot of the cytokines, these proteins, inflammatory proteins I talked about earlier, TNF, IL 6, these go up with poor diet. And I mentioned to you earlier, Those are the things that we target with our drugs, and so these things are all related concepts.

So by simply improving our diet, improving our gut health, and decreasing the dysbiosis that we experience, I think that that is leading to these improvements in our joints. 

Jonathan Wolf: You're very focused on measuring this level of inflammation in the body of your patients. You've talked about that quite, quite a lot.

You're saying that if I go and eat a typical Western diet, you know, all the hamburgers and all the rest of it, I come back in a year's time, you're going to actually be able to see that in the inflammation in my bloodstream with these markers. 

Tamiko Katsumoto: Yes. It's so fascinating. I don't know if you've ever gotten phlebotomized and people draw your blood.

Jonathan Wolf: I definitely have. 

Tamiko Katsumoto: But if you get your blood drawn after you eat a big hamburger or a big fried meal or something, I mean, it is striking. Blood normally is nice and deep red and pure and there's not, if you spin it down, you look at the serum layer, it's a nice clear layer. 

Literally minutes after you eat that hamburger full of saturated fat and whatever else is in it, that serum layer becomes cloudy and it's like all these lipid particles that end up going straight to your liver causing inflammation.

That stuff is coursing through your blood. And it's considered a hazard, your immune system reacts to that. And that's part of the issue is that we're getting this dramatic response to saturated fat. It's quite striking. 

Jonathan Wolf: That's quite a crazy picture you're painting. You're saying you can tell if I've just eaten about a hamburger, you don't even need to do the blood test. You can just look at my blood if you pull it out of my arm and that that you feel is not good. That is not sort of a normal situation. 

How profound a change were these participants having to go through in order to get this benefit? Were you having to go from literally your normal diet, which has got plenty of meat and of course, you eat some French fries and nobody's perfect to this perfect vegan diet where all you eat is rabbit food?

Is that what was required in order to have this impact? 

Tamiko Katsumoto: So dietary adherence I think was variable. I think they did see better improvements with those who were able to move towards more whole food plant-based eating patterns. I think that, so the intervention did include a lot of dietary counseling and a lot of kind of hand-holding, but I will tell you there is a preponderance of data that supports the whole food plant-based diet in terms of improved health outcomes.

I would say I would not call it rabbit food. I think that there's lots of yummy, delicious, as Christopher would say, Christopher Gardner would say, unapologetically delicious food. There's a lot that can be done in terms of plant-based, plant-forward, or I should say plant-centric eating.

But it's so clear to me, that the data supporting that dietary pattern with positive outcomes.

Jonathan Wolf: I guess what I was wondering is do you need to be perfect in order to get that benefit because obviously you're talking about a trial and I've spoken to other podcast guests who talk about like you can do a trial and you can get people to do something quite extreme for a month or a couple of months, but it's sort of not sustainable.

The question then is if you're not perfect at this. So let's say somebody listens to this and I don't want to be in a position where I never get to eat any red meat again. From your view as a clinician and a scientist, do you need to be perfect on this to get this benefit on arthritis? 

Tamiko Katsumoto: You don't need to be perfect. Nobody's perfect. Let me tell you some anecdotes that I think are really striking.

So I've actually had some very good luck coaching my patients towards more whole food, more plant-centric diets. A lot of them have improved. And then what happens is they have a slip up and they gorge on sugar or they gorge on a steak and they will literally feel it in their joints quickly.

And it's striking. 

Jonathan Wolf: So they, at this point, once they've made the change, you're saying that they can literally feel it later in the day or something. The impact on their body of that particular food. 

Tamiko Katsumoto: It's so fascinating. I've learned so much from my patients. I think some of them when they're really able to kind of get themselves to a really nice kind of homeostatic balanced point, their joints are doing well.

And then they slip up and they find trigger foods. It can literally happen in some patients within hours or a day or short periods of time. They can suddenly feel their joints light up. 

I think what's so exciting is that the joints, you don't feel your cholesterol going up, you don't feel your gluco- well, you have CGMs, but you don't feel your hemoglobin A1C rising up, right, for diabetes. But people feel their joints. And it's really incredible. 

In my patients who have come with me on this journey towards eating for health, I'm a huge believer in food is medicine, and those have done these N of 1 experiments, and then they have found you know, certain trigger foods.

So yes, you don't have to be perfect. It's so fascinating how food can reinforce, you know, what might be driving your underlying inflammation in a very tangible way, which I think is really striking. 

Jonathan Wolf: I think that's an amazing idea that you could actually eat a particular food and just feel it in your joints that it feels bad.

Because I think one of the things that is very hard about food is that for most of us, we're surrounded by this environment with all this delicious ultra-processed food everywhere. That's been designed by very clever scientists, right? That you can't stop eating it. And mainly, you're not really aware of how it's making you feel.

But it sounds like you're saying that if you're at the point where you are living with arthritis in a way you're sort of more sensitized. Clearly, our ancestors were quite happy to occasionally eat honey and fruits and the red meat whenever they could get it. And so it wasn't causing them any problems.

Here you're talking about these patients who can feel the negative impact immediately. What's going on here that they're having this different experience than our ancestors would have had. 

Tamiko Katsumoto: First of all, I think our ancestors probably had better gut health. And so, I think one thing that's so complicated is that when you have poor gut health, I think that's setting you up for an immune system that's primed to respond to different proteins, different antigens.

Like I said, the ones that are in the joint, there are T cells that may end up going to the joint. And so whether the food that we eat is basically triggering those T cells to get activated, you know, whether it's basically because you've got this leaky gut, breach of this gut epithelial barrier and your immune system, which is, by the way, the gut has the biggest immune system.

And whether then those T cells are getting educated to then they're getting activated and reactivated upon introduction of some of these trigger foods. I mean, that I think is a mechanism that is most likely to explain this gut joint connection. 

Jonathan Wolf: That's really interesting. So you're saying the microbiome you think is playing this very important role in how the food is then leading to inflammation. 

Do we know whether there's a positive impact here as well? Have they looked at the microbiome in this study, for example, or elsewhere and understood whether, by shifting this food, people living with arthritis are actually able to improve the microbiome and that's leading to these improvements?

Tamiko Katsumoto: Yes, I think the microbiome is a bit of a complex galaxy. I think that there's no one perfect microbiome. But I think one theme that keeps coming through in every study for having me, is that diversity of the microbiome is super important, and if we feed our microbiome good foods, we take care of it by eating, again, high fiber, lots of plants, good foods, then the good bugs will proliferate and predominate.

I think that the problem with our industrialized society and our diets is that we really have, unfortunately, a decrease in our gut microbiome diversity, which is a huge problem. 

So definitely studies have shown that patients with rheumatoid arthritis and a lot of other inflammatory diseases have a decrease in their microbial diversity in their gut.

Then just trying to figure out what are the good bugs, I think there are several different candidates, but it really is the composite mixture of bugs that leads to a good gut microbiome. There's not a one size fits all. 

Join the community

Be the first to know about ZOE’s breakthrough research, content from the world’s leading scientists, and more.

Jonathan Wolf: Now I know we focus a lot on arthritis, but I think taking us through this story with inflammation, I think you've already explained how much this is touching sort of almost all the other diseases, right, that are likely to affect us.

But one you haven't mentioned is something that I understand you're also involved in researching, which is that you're part of a multidisciplinary group that's looking at cancer at Stanford. Is that right? 

Tamiko Katsumoto: Absolutely, yes. 

Jonathan Wolf: Is there any connection between this chronic inflammation that we're talking about and cancer?

Tamiko Katsumoto: Definitely, and I think these are incredibly complex topics, but one thing that has come to light recently in the past less than a decade, is we are learning how important the immune system is in terms of cancer control.

So what's happened is the Nobel Prize was awarded in 2018 for the advent of what are called immune checkpoint inhibitors. To try to kind of distill this down, basically, the immune checkpoint inhibitors, these are these molecules, these antibodies that take the brakes off the immune system. 

So they inhibit the inhibitors of our immune system. And in doing so, it allows for this very robust immune response to occur, and hopefully, it means it's going to stimulate some of those T cells to attack our cancer cells, right?

Our bodies are constantly surveilling for cancer. We're probably developing little aberrant cells right here as we're sitting, as we speak, and because we hope our immune systems are good, we're clearing those cancer cells. But you can imagine when you have aberrant inflammation, your immune system may be somewhat compromised in clearing those cells.

So we're learning that, for example, cancer is becoming more and more common. And we're seeing it in younger and younger people. And so, there's probably a role for the immune system, again, our gut microbiome. These are so many complicated concepts to try to tie together. But I'll just go back to the checkpoint inhibitor example because I think it's really interesting.

Immunotherapy is really helping to stimulate our immune systems to kill our cancers. Unfortunately, our immune systems then can get so activated they can end up attacking different organs of our body as well, including our joints, our skin, our lungs, and other places. And one thing that we've learned is that diet plays a really important role in the immune immunotherapy response.

So scientists at MD Anderson have shown some really beautiful data when they looked at patients with melanoma, which is a type of skin cancer, who were receiving this immunotherapy. They found that the patients who had the most robust response to clear their cancer were the ones who were on high-fiber diets.

They're finding that the patients who had the most diverse microbiomes, right, those were the patients who ended up having a more effective anti-tumor response. And I think other data, we're learning that similarly, I think, our gut microbiomes are really important in mediating and tuning our immune system to prime us to kill off these cancer cells.

Jonathan Wolf: You're saying that there's some recent papers looking at patients fighting cancers using these new immunotherapies, and you're saying that the patients on diets with more fiber, which we know is this key thing that feeds the gut microbiome. 

And also people with this more diverse microbiome were actually having a better response when they took this immunotherapy. So it's been more successful for fighting cancer. 

Tamiko Katsumoto: Exactly. 

Jonathan Wolf: So I'm pretty stunned by that. You're looking at me as though, yeah, that's sort of obvious. Have we known about that for very long? 

Tamiko Katsumoto: No, we haven't. And no, this was not obvious to me either. I'm thrilled because it obviously is concordant with everything we think has been true about the gut microbiome.

But I think it raises the issue that really our microbiome is playing such an important role in modulating our immune system and tuning it to optimize our health. Protecting us from autoimmunity, protecting us from cancer, protecting us from, you know, other infections. 

I think it's becoming so central to what we call immune homeostasis. The real kind of just the balance of everything in our bodies. So I encourage my patients who have cancer to really be thinking about their diet seriously. Because I think that our diets play a huge role in not only response to immunotherapy but also other cancers as well. 

We know colon cancer is very closely associated with our diets, as well as other GI cancers.

So I'll mention to you, the National Cancer Institute has identified 13 cancers that have been definitively associated with obesity. We know obesity is obviously very much associated with our diets. A lot of these cancers tend to be gastrointestinal, GI-related cancers, esophagus, stomach, liver, pancreas, gallbladder, and then of course colon.

A lot of the other cancers that are listed on this list of 13 are hormonally driven cancers, so breast, uterine, those types. So I think that we are starting to really appreciate the role of diet and inflammation that probably plays a really fundamental role in our protection against these cancers.

Jonathan Wolf: I think that's really amazing. A little terrifying because of course the diets that we are eating, whether I'm here in the States or I'm in the U.K. or Australia or it doesn't really matter, are really low on the sorts of foods that support our microbiome and really heavy in the sorts of ultra-processed foods that are bad.

I just want to clarify one thing because you've talked a lot here about how you might be able to improve your diet if you were fighting cancer or something like that. 

I think you're also saying that if I am just eating a traditional Western diet, that this is going to be directly leading to this higher inflammation and that that inflammation is then liable to increase my risks of not just what we were talking about before, the heart disease and arthritis, but also things like cancer.

Tamiko Katsumoto: Yes, I should mention the WHO has declared that processed meats and red meats are considered carcinogenic. And so again, we're seeing kind of this incredible uptick in our meat consumption when you look over the past century. 

I think we need to keep that in mind that not only is it not good for the environment to be eating red meat, but it's also really a problem, I think, in terms of just cancer generation, colon cancer rates are going up. In the United States, we've decreased the age for screening for colon cancer now to 45, used to be 50, now it's 45. 

So I think that our poor Western diets, full of ultra-processed foods, full of meats, especially red meats, I think that is driving this uptick in cancer that we all need to be wary of. 

Jonathan Wolf: Tamiko, I think you've painted a really strong picture about why the food that we eat can really affect you. And I think having gone in talking very specifically about arthritis, I think you've really pushed it open as well to think about the broader impact. 

I'd love to talk now about actionable advice.  I imagine a listener here is living with arthritis, or they know someone who is and they'd to go and share this podcast with them and make sure that it's really practical.

I understand that you and your colleagues have built a new food pyramid as a way to think about how you could put these anti-inflammatory foods into your diet. It's pretty different from the food pyramid that I grew up with. 

Could you take me through it? 

Tamiko Katsumoto: You're generous. We haven't built a new food pyramid, but we adhere to or we promote a couple of food pyramids that I'm particularly keen on.

Andrew Weil, who is kind of one of the founders of integrative medicine, I think puts out a very nice anti-inflammatory pyramid. And the other pyramid that I like, I don't know if it's a pyramid, but I am a big fan of Dan Buetner's Blue Zones. 

I think that people are probably familiar with Blue Zones where Dan Buettner studied the centenarians of the world. There were five areas, there's now six, Singapore got added, where people tend to live to a hundred. 

Studying their diets and behaviors, I think, has been very informative because We're never going to run a diet study for 100 years. Let's face it, right? All these wonderful RCTs are short-term. I love the fact that there's now this pattern, this dietary pattern that is associated with good health, and good quality of life.

Jonathan Wolf: And I would just like to add that we actually did a podcast with Dan Buettner a little while ago, which was lots of fun and he explained the blue zones and what they were doing. He also gave this amazing recipe for a soup in there, which I can recommend. So if anyone's interested, they can search just for Blue Zones or Dan Buettner, and they will find that episode.

So tell me what's on the plate. 

Tamiko Katsumoto: I like the kind of my plate. This is sort of the approach where you take a plate and you divide it up and really half of it is fruits, vegetables, you know, good stuff. The whole concept of eating the rainbow I think really is apropos because these are foods that are high in phytochemicals, a lot of the antioxidants that are super important for calming down our immune system.

Cruciferous vegetables, these are things like broccoli, and kale, and cauliflower, and these really kind of the deep leafy greens that I've come to love and embrace. And they're so important. I really think food is medicine. And these are incredibly important in terms of helping our liver detoxify.

We're living in a very polluted world. And I think that these are super helpful foods that can help us clear our body of a lot of these toxins, these endocrine disruptors, which we haven't talked about. But there's a lot of these things that we need to be thinking about that are super helpful for my patients.

So half of the plate, I think focusing on high-quality vegetables, some fruits, and then a quarter of the plate being proteins, preferably plant proteins or lean proteins, but things like beans and lentils. I'm a big fan of tofu. 

Then whole grains. I think the thing to keep in mind is that as we know with our ultra-processed foods, we tend to eat a lot of these very refined grains. The white rice, white pasta, white bread, these things that have had a lot of the nutrients stripped out of them and a lot of the fiber stripped out.

So refined grains are where we want to go. And so really whole wheat and whole things like quinoa I love. And some of these ancient grains are also really good, like farro and bulgur and millet.

If you kind of imagine, I guess it's really the plate method, the pyramid method is a little more complicated to think through, but those are the key staples that I try to encourage my patients to aim for. 

Again, animal products in moderation, really limiting them. If you look at the blue zones, they say that the majority of blue zones end up eating meat less than five times a month. So really that comes down to maybe once a week. Meat should be considered a treat. 

The other thing I'll mention that I love about the blue zones is that one thing that was commonly shared across all the five blue zones is they all ate half to one cup of beans a day, beans or lentils. So these legumes that are so good for us, packed with protein, packed with fiber.

Another food type that I love a lot are things like chia seeds and flax seeds. I think chia seeds are the perfect food. They're high in fiber, high in omega three, high in protein. They've just got so many great components that I add them to my smoothies. I just try to incorporate them wherever I can. I get a big bottle of them and add them wherever I can. 

Jonathan Wolf: Is there any view around oily fish and arthritis because I know that there's a sort of spread of opinion I feel between the people that I interview. But there seems to be quite a lot of people talking about oily fish as being beneficial.

In general, you've been talking about very much plant-centric diet. What's the evidence with people with arthritis? 

Tamiko Katsumoto: So fish I think can be a helpful component because of the omega-3. So we know omega-3 fatty acids are incredibly anti-inflammatory. That being said, I also encourage my patients to not go too heavy on fish, to eat the smaller fish, so not so much the tuna and the swordfish, you know, things that are much larger and can end up bio accumulating things like heavy metals and toxins. Trying to go for the wild-caught instead of the farmed.

But again, I would say, What do I do?  I end up taking the vegan omega-3, which is from algal sources, so algae. I think there are different ways of getting omega-3s. I mentioned chia seeds also have them and there are different types.

So fish I think, it can be a good thing, but not to overload. And I tend to also recommend, I tell my patients, you know, check out the Monterey Bay Aquarium's resource called seafoodwatch.org. 

Seafood Watch has a lot of examples where what's sustainably caught and which ones are thought to be healthier. You know, we have to be thinking about pollutants. Our oceans are not the cleanest, so we have to be thinking about that as well. 

Jonathan Wolf: It's really interesting. One thing I haven't heard you mention is probiotics, live bacteria to go into your prebiotics or fermented food, or things like this. Does any of that matter as we're thinking about inflammation and arthritis? 

Tamiko Katsumoto: Absolutely. We don't have data yet specifically on arthritis, but I will say this, the prebiotics and probiotics are all so critical in maintaining a very healthy gut microbiome. 

I think the best study on this is called the Fe-Fi-Fo study, done by my colleagues, Christopher Gardner, Justin Sonnenberg, and Erika Sonnenberg, where they did a very elegant study using equipoise meaning they didn't try to game the system in any way. 

They basically put a head-to-head high-fiber diet compared to a high probiotic diet using fermented foods as the source of a lot of these bugs. And they ran this study, head-to-head comparison didn't know which one was going to end up being more, quote, anti-inflammatory.

And what was so fascinating about this study is it was the probiotic fermented food arm that ended up showing a more substantial anti-inflammatory effect. 

That being said, the devil's in the details. So basically, the fiber was super, super important in having an anti-inflammatory effect, but that was seen only in the subgroup of patients who already had a very robust, diverse host microbiome.

In the participants who ended up not having as much gut microbiota diversity, they ate a ton of fiber and they ended up actually getting more inflammation. 

So it was really about, I think about it as the soil and the seed, the soil being the fiber that we need to consume, the prebiotics that are feeding our gut bacteria, that are helping our gut to maintain the epithelial barrier integrity, and then producing that very strong mucus layer that is the important barrier.

We need the fiber for those reasons, but we also need the fermented foods that have the bacteria that populate our gut microbiome, and you need both of them together in concert in order to have a very healthy diverse microbiome that protects us against inflammation. 

Jonathan Wolf: And one thing I'd like to clarify because you talked about probiotics and you talked about fermented food and I think most people when they think about probiotics think about a capsule that they can buy from the store and pop. Fermented food, they think, well, that's something that I buy from the supermarket and it's a food.

Were you testing both at the same time? 

Tamiko Katsumoto: So I guess one could argue fermented foods have a lot of these probiotic bacteria in them. And they're very effective as probiotics. I'm referring to those. I think capsules are interesting, I'm not sure how effective they are compared to just eating probiotic foods that are full of these good bacteria that end up staying in our gut.

Jonathan Wolf: So when you're saying taking probiotics, you're actually meaning eating these fermented foods full of live bacteria. From a yogurt to a kimchi. 

Tamiko Katsumoto: Exactly. Sauerkraut, kefir. 

Jonathan Wolf: You're not talking about individual capsules. So within this plate and this design, are you recommending people take these probiotic capsules or are you actually saying, no, I'm recommending these fermented foods?

Tamiko Katsumoto: I think of food as medicine, so I would encourage my patients to incorporate as many of these fermented foods as they're able to because that really helps. 

Especially after, let's say, they've taken antibiotics for some sort of infection that can deplete the microbial diversity. Eating fermented foods provides a lot of the bugs that help to repopulate our gut, really providing the seeds, as you then chase that with fiber, which is the soil, the prebiotics.

I think both are equally important in terms of really creating a good gut microbiome. 

Jonathan Wolf: We're sitting in California today, and I feel like the number one question that we would get from listeners who are in California to this is that all sounds great, but I'm really worried that I'm not going to get enough protein in the plate that you've just described, and I know that protein is really important for my health, but you've just taken sort of all of that.

You haven't even really pushed meat at all. Aren't you worried that your patients aren't getting enough protein? 

Tamiko Katsumoto: When we think about protein, you know, not to get too far into the details, I think that the recommended daily allowance is 0.8 grams per kilogram. So let's say for a 150-pound sedentary person, it's about 50-something grams of protein, which can easily be achieved with a lot of the plant-based foods.

When you think about tofu and tempeh and soybeans and all these other beans and lentils and whole grains also have protein. And so I think that people are almost a little overly obsessed with protein. 

The RDA, by the way, really is even a high estimate of what we need. It's two standard deviations above the average. So, I think what I am focused on is we are very fiber deficient in our diets and that in general, the vast majority of us are, we have too much protein in our diets. 

I'll just also make the point that protein cannot be stored. So protein can be kind of in the instant can be converted into glycogen as a source of energy, but the remainder, the excess, ends up getting converted into fat.

So I feel like all the excess protein we're dumping into our bodies could be actually causing more problems. So we need to be thinking about that. You know, kidney patients, can't tolerate too much protein either, so I don't have concerns about too little protein in our diets. 

Jonathan Wolf: You talked a lot about fiber.

I just have one specific question, which is, how much should someone be looking to eat during the week? Because you talked about the importance of that for feeding the microbiome and then pulling down this inflammation. 

If someone was trying to understand, what should they be trying to achieve and what's the average American actually eating today?

Tamiko Katsumoto: So the average American is eating about 15 grams of fiber, and the amount we should be targeting is between 28 to 35 grams of fiber. 

That being said, there's a tribe in Africa, the Hadza tribe, Dustin Sonnenberg and his group studied this incredible group of folks, and they were getting upwards of 100 grams of fiber in their diet.

Jonathan Wolf: A hundred grams.

Tamiko Katsumoto: A hundred grams of fiber. 

Jonathan Wolf: And the average American is eating 15. 

Tamiko Katsumoto: Yes. And the Hadza's, you know, they had no chronic diseases, no issues with inflammation, incredibly healthy. 

So I think that it just goes to show how little fiber we have been eating and how much that's probably impacted our gut health. So to get that fiber, again, fiber is only found in plants. 

Jonathan Wolf: Final question, because we're over time, it's been fascinating. You've laid out a really big overhaul to our diet. And so lots of people listening to that will be saying, I'm not ready to make all of those changes. If you were going to say to them, here's one small change that you can make tomorrow.

Tamiko Katsumoto: Start small. I make swaps that are barely noticeable. So I tend to like plant-based milks, soy milk, oat milk, things like that. Or take a day of the week, do the Meatless Monday where meat becomes the condiment. The main highlight is the plants in your meals. 

This doesn't have to be overnight. Again, I don't think that the goal is that the world is going to turn vegan, but I do feel like we do need to move in that direction in terms of really, I mean, there's so much evidence supporting plant-centric eating patterns that correlates with good health, with less inflammation, with a lot of these chronic diseases that are plaguing our society.

Not to mention that it is a helpful thing for the planet and a helpful thing for so many other things. 

Jonathan Wolf: Tomiko, thank you so much. I would like to try and do a quick summary and this is a new topic for me. So please correct me if I’ve got anything wrong.

So if I think back across it, the thing that's most in my mind for most of us eating the regular diet, our whole body is on fire with inflammation. And which is like this terrifying image of every bit of it, burning down. 

The issue is that inflammation is like our damage repair system, so we need to have some, but it's supposed to just come on some of the time. But because of the food that we're eating and the lives that we live, it's switched on all the time. And this is your image of it all sort of burning down. 

Diet is the central issue here that you're saying is causing this inflammation because of the sorts of foods that we eat. But critically also that our microbiome is so damaged compared to the microbiome of our ancestors and that our ancestors had this much better gut health that really protected them.

Where today, because of what we have combined with our food, we're having this always-on inflammation, and that is not just leading to sort of the arthritis that we spent a lot of time talking about, but actually it's this risk factor for any autoimmune disease, but also cancer and heart disease and all the rest of it.

You gave this brilliant story of saying, well, you know, if I ate a big hamburger right now, and then you took my blood a few minutes later, you'd actually see in my blood that it just doesn't look like it normally does. And it's cloudy and it's full of all this saturated fat. And that is like this first step leading to inflammation, which is a very scary image.

We talked a bit specifically about how this links to arthritis. You said there's two main types of arthritis that listeners might be living with. Osteoarthritis, which you said is the most common, which historically we thought of as only wear and tear. But you're saying now you think there is this inflammatory component because you see the impact of food improving it.

Then rheumatoid arthritis, which we know is this sort of autoimmune, meaning it's like our own body attacking us. And it's this very direct explanation of how the inflammation is causing this problem. Therefore, if you can reduce the inflammation through food, you ought to really be able to have this direct impact.

You, I think, painted a picture of just how much this impacts your quality of life. And so this is another way in which, if you can't keep the inflammation under control, we end up having our quality of life really impacted. 

Now all of that was a bit depressing, but then I think you switched to actually really positive news that it is possible, within eight weeks of changing your diet, to have a profound impact on your arthritis because it's having this profound impact on inflammation.

And then you described to us an anti-inflammatory plate. The plate that you take to your patients in Stanford. And what I took away was, for your plate, half this plate is vegetables and fruits. You want to eat the rainbow. 

You particularly like certain plants that you felt were particularly good for anti-inflammatory properties; broccoli, kale, cauliflower. This was your cruciferous. I don't know what else is in cruciferous. I'm going to look that up later. 

You were selling chia seeds as another one that you really feel packs all of this in. 

A quarter of the plate is protein. But when you talked about protein, you immediately went to beans, lentils, and tofu. So you're talking about plant proteins because they were giving you protein, but they were also giving you all of this fiber and more of this anti-inflammatory.

And then the other quarter being whole grains. So avoiding all the traditional sort of refined grains. I was brought up with, you start with potatoes and pieces of bread. And here you're talking about whole wheat, but also quinoa. And you mentioned a lot of fun, like ancient grains that I think, were not in my supermarket 20 years ago, but are now like faro and bulgur and millet. I don't know what millet is, but I'm gonna look that one up as well. 

And then animal products, you can have animal products, but you want this to be in moderation. So rather than your plate is mainly a piece of meat with a little bit around it, you're going to have it from time to time. 

Oily fish can be helpful. If you don't want to eat fish at all, then you're talking about supplements that allow you to get those, those omega 3.

But what you're saying is, I just want to play this back because it is sort of amazing. You're saying if you are living with arthritis and you were to make that sort of change in your diet, you think it can really change not only your symptoms but even potentially get you to a point where you say, I don't even need to take all the medication I'm taking today.

Tamiko Katsumoto: Absolutely. Incredible summary, Jonathan. Thank you so much. 

Jonathan Wolf: You're very welcome. Thank you.