Dr. Tamiko Katsumoto is a Stanford rheumatologist specializing in immunology and inflammation. She is both physician and scientist who gets over-the-top raves from her patients.
The Protective Power of Food Against Joint Pain
An Interview with Dr. Tamiko Katsumoto, Stanford Rheumatologist
Viva Longevity, June 2025
Participants
Dr. Tamiko Katsumoto – Stanford rheumatologist, immunologist, and researcher
Michelle – Interviewer
Chris – Interviewer, video editor
Introduction
Michelle: Dr. Tamiko Katsumoto swept us away when she lit up the stage at Stanford's Health Matters Summit.
Tamiko: I'm so looking forward to speaking with you today about something near and dear to my heart: food's protective power against disease. As a rheumatologist, I deal with chronic inflammation all the time.
Background and Clinical Perspective
Tamiko:
Grew up in the Bay Area, completed medical training at UC San Francisco, including basic science research in immunology.
Worked in drug development at Genentech, then returned to clinical care at Stanford in 2018.
Focuses on immuno-oncology and immune complications, learning that diet plays a pivotal role in modulating immune and inflammatory responses.
Emphasizes that "food is medicine," especially for patients with autoimmune diseases and systemic inflammation.
Diet and Inflammatory Disease
Michelle: What do you see in patients with arthritis or autoimmune conditions? Do you advocate a plant-based diet?
Tamiko:
Moving patients toward a plant-centered diet often improves their symptoms.
There is cultural emphasis on protein and meat, but patients adhering to meat-heavy diets often experience joint flares.
Notably, patients who reduce or eliminate red meat and increase plant foods see improvements in joint pain.
Key Study: "Plants for Joints"
Dutch randomized controlled trial compared standard care to a lifestyle intervention based on six pillars of lifestyle medicine:
Diet (whole-food, plant-based, no ultra-processed foods)
Exercise
Sleep
Low stress
Sense of community
Avoidance of risky substances
In 16 weeks, patients with rheumatoid arthritis and metabolic osteoarthritis improved substantially, with objective joint scores (DAS 28) showing significant benefits—comparable to pharmaceutical interventions.
Conclusion: Plant-centered diets and lifestyle changes can meaningfully reduce inflammation and improve quality of life.
Carnivore Diets and Gut Health
Michelle: Have you had patients try a carnivore diet?
Tamiko:
Some patients report temporary relief by eliminating potential food sensitivities, but long-term carnivore diets are "really terrible for gut health."
The gut microbiome depends on fiber, which is absent in animal products.
Lack of fiber results in a less healthy gut microbiome, associated with increased cardiovascular risk and less production of protective short-chain fatty acids.
Recent large studies (e.g., ZOE Science and Nutrition, 21,000+ participants) show vegan diets enrich beneficial gut bacteria and metabolites that calm the immune system.
Food Intolerances and Gut Healing
Food intolerances are complex and not always permanent.
Patients should experiment by eliminating and slowly reintroducing foods ("N-of-one" experiments).
Digestive enzymes (e.g., Beano), probiotic/fermented foods, and gut-healing supplements (e.g., L-glutamine) can help.
Healing the gut may allow patients to tolerate previously problematic foods.
The Stanford PLANT Study
PLANT: Providers Learning About Nutrition Together.
Randomized, delayed-intervention study for healthcare providers (physicians, dietitians, trainees).
Six-week nutrition education program included lectures (e.g., Christopher Gardner), practical cooking classes, and sustainability topics.
Over 100 providers participated; significant improvement in readiness to counsel patients on plant-based diets.
Many providers expressed gratitude and interest in broader implementation.
Patient Communication and Barriers
Many patients are unaware of how to transition to plant-based diets or how to cook plant foods.
Even brief mentions of diet by physicians can have a significant impact.
Plant-based meats have a much lower carbon footprint and can improve lipid profiles compared to animal meats.
Physicians should not shy away from discussing diet; patients are often grateful for the guidance.
Environmental Toxins, Bioaccumulation, and Food
Michelle: Can you explain bioaccumulation and contaminants in food?
Tamiko:
Persistent organic pollutants (POPs), such as dioxins and certain pesticides, are fat-soluble and accumulate in animal tissues.
Animal products tend to have higher concentrations of these contaminants due to bioaccumulation.
Plastics (phthalates, BPA/BPS) and other chemicals also accumulate more in fatty, animal-based foods.
Regulatory oversight is limited; more research is needed on food contaminants.
Eating more plants, especially those high in fiber and antioxidants (e.g., cruciferous vegetables), can help detoxify and excrete environmental toxins.
Practical Resources
Environmental Working Group (EWG):
"Dirty Dozen" and "Clean 15" lists for pesticide contamination in produce.
Tap water database for local contaminant profiles.
Database of personal care products and their chemical risks.
Climate Change and Rheumatic Diseases
Climate change increases risks for autoimmune and rheumatic diseases via air pollution, wildfires, and stress.
Air pollution is linked to more frequent flares of diseases like rheumatoid arthritis, lupus, and gout.
Literature on direct links between climate change and rheumatic disease is limited, but the concern is growing.
Lessons from Drug Development
Drug development is high-risk; 90–95% of drugs fail to reach approval.
Chronic-use drugs (like Ozempic) are more financially attractive to develop than one-off treatments (like antibiotics).
Antibiotics are used chronically in animal agriculture to promote growth, raising concerns about antibiotic residues and microbiome effects in humans.
Food Systems, Sustainability, and Climate
Food production uses 38% of Earth's land; animal agriculture dominates this use and is responsible for a significant share of greenhouse gas emissions.
The entire food system accounts for approximately 34% of global greenhouse emissions.
Cross-disciplinary collaboration at Stanford is fostering innovative solutions in food, sustainability, and health.
Summary and Takeaways
Plant-centered diets are supported by robust evidence for reducing inflammation, improving gut health, and lowering exposure to environmental toxins.
Physicians and healthcare providers play a crucial role in patient dietary choices and should be empowered to discuss nutrition.
Environmental and food system changes are necessary for both human and planetary health.
References (for further reading):
Stanford PLANT Study: Providers Learning About Nutrition Together (PLANT)
Plants for Joints Randomized Controlled Trial
Gut Microbiome Signatures of Vegan, Vegetarian and Omnivore Diets
Environmental Working Group
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