Inflammation is the body’s healing response to injury or infection. When you sprain your ankle, it swells up because your body releases compounds to help it heal. As it heals, those inflammatory compounds are lessened. Similar processes happen when you get sick with an illness, except the inflammation may not be so obvious. 

Inflammation is a necessary part of healing, but when that inflammation doesn’t go away and becomes chronic, it raises your risk of conditions including heart disease, cancer, diabetes and metabolic syndrome. Many things can cause chronic inflammation, including stress and diet. 

Researchers in the United Kingdom took a closer look at diet—specifically protein sources and fiber—and how they relate to inflammation. They published their findings in April 2025 in Nutrients. Let’s break them down.

How Was This Study Conducted?

The data in this study came from the UK Biobank, a large database that contains medical, lifestyle and health information from about 500,000 UK residents. For this study, researchers used data from 128,612 participants who were at least 60 years old and fit the study criteria. The research team only included participants who had dietary data and bloodwork that included C-reactive protein (CRP) levels on file. CRP is a common measurement of inflammation in the body. 

Researchers categorized participants into two groups: individuals who had one or no chronic health conditions (based on a list of 43 such conditions) and individuals who reported having two or more of those chronic conditions, which is referred to as multimorbidity. 

Based on food diaries from the participants, researchers recorded total protein intake and broke it down into animal protein and plant protein categories. For this study, plant protein included tempeh, tofu, beans (legumes), lentils, nuts and seeds. Animal protein included red meat, poultry, eggs, fish and dairy. In addition, participants’ fiber intake was calculated. 

Researchers adjusted for factors like age, sex, ethnicity, socioeconomic status, smoking status, alcohol intake, height and weight. Participants self-reported medical diagnoses from a list of 43 conditions. 

Based on their dietary information and CRP levels, participants were divided into groups: high total protein, low total protein, high dietary fiber and low dietary fiber. These groups were further split up, with low, middle and high categories in plant protein, animal protein and dietary fiber. 

What Did This Study Show?

After statistical analyses were run, researchers found that plant-based protein and high-fiber foods may be linked to lower inflammation in the body. Specifically, they observed that: 

• Participants eating a diet low in fiber and high in animal protein experienced higher inflammation levels.
• Within each category of high, middle and low protein intake, higher inflammation levels were always observed for those who also had low fiber intake. 
• In those without multimorbidity (two or more chronic diseases), higher plant protein and fiber intake was associated with lower levels of inflammation.
• For those with multimorbidity (two or more chronic illnesses), the association between protein, fiber and inflammation was stronger compared to those without multimorbidity.

Overall, as plant protein and fiber intake increased, inflammation levels decreased. The opposite was found regarding animal protein and total protein, which exhibited a significant positive association with CRP.

There were a few limitations to this study. First, the study population was largely white British older adults, so it is unknown if these results also apply to other populations. It’s also worth noting that when participants self-report their conditions and dietary habits, there’s always a chance that some data may be incomplete or misremembered. Lastly, CRP levels were only measured at baseline, so they might not be indicative of ongoing chronic inflammation. 

How Does This Apply to Real Life?

We know that inflammation plays a starring role in chronic illness. The trick is finding out what’s causing it. This study suggests that consuming high amounts of animal protein and too little fiber are associated with higher levels of inflammation, and that higher intakes of fiber and plant protein are linked with less inflammation. 

Fiber plays an important role in gut health, providing food for beneficial gut bacteria. There is evidence that a healthy gut microbiome is linked with lower inflammation levels, so it makes sense that plant protein and other sources of fiber would be associated with lower CRP levels. And this relationship is bi-directional—gut health influences inflammation, and inflammation influences gut health.  

If this is all overwhelming, a good place to start is with gut health. We know that fiber feeds the beneficial gut bacteria and plant protein provides fiber, so start there. What sources of plant protein can you add to your diet? Where can you swap an animal protein meal with a plant protein one? Higher protein plant sources include legumes, nuts, seeds, tofu, tempeh and certain whole grains, like quinoa and amaranth. This weeklong plant-based diet meal plan provides a framework to get you going. Use it as is or pick out a few recipes to try. 

Even if they aren’t considered high-protein, other plants—including fruits, vegetables and whole grains—are also important to include for gut health and overall good health, as they provide fiber, antioxidants and essential vitamins and minerals. 

You also need plenty of beneficial bacteria—aka probiotics—to nosh on the fiber you’re feeding them. You can get probiotics from fermented foods, so add a little sauerkraut or kimchi to your diet each day. If that’s not appealing, then go with yogurt or kefir.

Another limitation of this study is that it didn’t break down healthier sources of animal proteins from less healthy ones. For example, yogurt and kefir are sources of animal proteins that provide probiotics and other necessary nutrients, including calcium and vitamin D. And fish and other seafood provide brain- and heart-healthy omega-3s in addition to protein. But these proteins were all lumped together with other sources of animal proteins, even though they provide a wealth of essential nutrients. 

We believe that all foods can fit into a balanced, varied diet. While you might not want to eat a hamburger every day, now and then is probably fine. Instead of cutting things out, focus on packing your diet with nutrient-dense foods that have been linked with lower levels of inflammation and disease (like plant protein) while sprinkling in other foods you enjoy on occasion (like a burger). 

Other lifestyle habits have also been linked with better gut health and lower levels of inflammation, including exercise and lower levels of stress. So, move your body more often and examine the areas where stress needs to be lowered. 

The Bottom Line

A new study in Nutrients suggests that higher plant protein and fiber intake is associated with lower levels of inflammation, and that higher animal protein and lower fiber intake are linked with higher levels of inflammation. Eating more plants, including high-protein plants, is important for overall health and disease prevention.

Find easy ways to add more plant protein and fiber into your diet, and start swapping animal protein for plant protein here and there. Some tasty ways to do this are by replacing the meat in tacos with tofu, like we do in our Chipotle Tofu Tacos, or with beans, like in our Crispy Sheet-Pan Black Bean Tacos.