Plant-based diets may reduce chronic inflammation: Meta-analysis of 7 clinical trials found reduction in C-reactive protein

The study examined the impact of plant-based diets on C-reactive protein levels, one of the most commonly used laboratory markers of systemic inflammation. The authors evaluated randomized controlled trials, a more rigorous type of clinical data, rather than observational studies, where it is difficult to separate diet from lifestyle.

Key finding: In a pooled analysis of 7 clinical trials involving 541 people, plant-based diets were associated with an average reduction in C-reactive protein levels of 1.13 milligrams per liter compared to omnivorous diets.

The authors emphasize that the result appears biologically plausible, but the evidence base is still limited: of the nearly 3,000 publications identified, only 7 met the strict criteria for randomized trials. Therefore, the conclusion of this news should be cautious: a plant-based diet may reduce inflammation, but larger, higher-quality studies are needed.

Parameter	Data
Article Title	The effect of plant-based dietary patterns on C-reactive protein
Publication type	Systematic review and meta-analysis of randomized controlled trials
Magazine	Nutrition, Metabolism and Cardiovascular Diseases
Year	2026
DOI	10.1016/j.numecd.2026.104631
Number of included tests	7
Number of participants	541
Main marker	C-reactive protein
The main result	A decrease in C-reactive protein of 1.13 milligrams per liter

What happened?

Researchers from the University of Warwick analyzed whether switching to a plant-based diet could reduce C-reactive protein levels compared to a typical omnivorous diet. This is an important question, as chronic low-grade inflammation is increasingly being considered as a mechanism of aging and age-related diseases.

In English-language scientific literature, the term "inflammageing" is often used for this phenomenon. This refers not to an acute infection or a high fever, but to a long-term, low-grade inflammatory background that can contribute to the development of cardiovascular diseases, type 2 diabetes, and some cancers.

Plant-based diets are gaining attention because they typically contain more vegetables, fruits, whole grains, legumes, nuts, and seeds. These diets are often rich in dietary fiber, antioxidants, and unsaturated fats, while they typically contain less saturated fat than diets rich in animal products.

The study's novelty lies in the authors' focus on randomized clinical trials. Previously, the link between a plant-based diet and lower inflammation has often been demonstrated in observational studies, but it's more difficult to prove causality in these studies: people who choose a plant-based diet may simultaneously be more physically active, smoke less, and generally be more mindful of their health.

Why is this work important?	Explanation
An inflammation marker was studied	C-reactive protein reflects the systemic inflammatory background
Randomized trials were used	This is stronger than observational data for assessing a causal effect.
Different plant-based diets were considered	Included vegan, vegetarian, and whole food plant-based models
The comparison was with an omnivorous diet.	The difference between diet types was assessed
The evidence base is still small.	Only 7 trials were included in the meta-analysis

What is C-reactive protein and why is it important?

C-reactive protein is an inflammatory response protein produced primarily in the liver. Its levels increase with infections, injuries, and active inflammatory diseases, and can also be moderately elevated in chronic metabolic stress, obesity, and cardiovascular risk.

In this study, C-reactive protein is of interest not as a marker of acute illness, but as an indicator of underlying systemic inflammation. It is precisely this moderately elevated inflammatory background that can accompany metabolic disorders and vascular aging for years.

The authors of the University of Warwick press release point out that C-reactive protein levels are also used to assess cardiovascular risk: values below 1 milligram per liter are generally considered low risk, while values above 3 milligrams per liter are considered high risk. Therefore, a decrease of 1.13 milligrams per liter may be clinically significant for some people, especially if the baseline level was borderline.

But it's important not to use this indicator as your sole goal. C-reactive protein doesn't pinpoint the source of inflammation, nor does it replace assessment of blood pressure, blood lipids, glucose, body weight, smoking, sleep, and physical activity. It helps us see part of the picture, but not the whole.

C-reactive protein level	Possible clinical interpretation
Below 1 milligram per liter	Generally associated with lower cardiovascular risk
1-3 milligrams per liter	Intermediate risk zone
Above 3 milligrams per liter	May indicate higher cardiovascular risk
Sharply elevated values	Requires a search for infection, inflammation or other active cause
A decrease of 1.13 milligrams per liter	May be significant if baseline levels were moderately elevated

How the meta-analysis was conducted

The authors searched MEDLINE, Embase, and Web of Science for studies. They were interested in clinical trials that compared plant-based diets with omnivorous diets and measured C-reactive protein levels.

The initial search identified 2,962 publications, but after rigorous selection, only seven randomized controlled trials remained. These studies yielded eight data sets and included 541 participants with a median age of approximately 55 years.

The analysis included various plant-based diets: vegan, vegetarian, and whole-food plant-based diets. This is important because a "plant-based diet" does not always mean a complete abstinence from all animal products; some models emphasize the prevalence of whole plant foods.

To combine the results, the authors used a random-effects model and assessed the risk of bias, data heterogeneity, and sensitivity of the results. This is a standard approach for meta-analysis, where trials may vary in duration, diet composition, participants, and concomitant interventions.

Element of analysis	What the researchers did
Search bases	MEDLINE, Embase, Web of Science
Publications found	2962
Included tests	7
Data sets	8
Participants	541
Median age	55 years old
Comparison	Plant-Based Diets vs. Omnivorous Diets
The merger method	Random effects model

Key results

In the overall analysis, plant-based diets reduced C-reactive protein levels by 1.13 milligrams per liter compared to omnivorous diets. The 95% confidence interval was -1.52 to -0.75 milligrams per liter, indicating a statistically significant benefit in favor of plant-based diets.

The authors separately tested whether the effect persisted after excluding studies that combined diet with structured physical activity programs. After excluding these studies, the reduction in C-reactive protein persisted, but was slightly smaller: -0.94 milligrams per liter, 95% confidence interval (CI) -1.43 to -0.46 milligrams per liter.

This is important because physical activity itself can reduce inflammation and improve metabolic health. If the effect persists even without studies involving exercise programs, then the contribution of diet itself appears more compelling, although the influence of other factors still cannot be completely ruled out.

The authors emphasize the high heterogeneity of the data and the low certainty of the evidence. Simply put, the direction of the effect appears promising, but the number of studies is small, and the trials themselves vary widely. Therefore, this is not a definitive verdict, but a strong signal for further research.

Analysis	C-reactive protein result	Interpretation
All 7 tests	-1.13 milligrams per liter	Significant reduction compared to an omnivorous diet
95% confidence interval	-1.52 to -0.75	The result statistically supports the decline
No exercise testing	-0.94 milligrams per liter	The effect persisted, but was slightly less.
95% confidence interval	-1.43 to -0.46	The decline remained statistically significant
General confidence	Low	Larger trials are needed

Why a plant-based diet could reduce inflammation

One possible mechanism is increased dietary fiber. Fiber influences gut microbiota and the production of short-chain fatty acids, which may play a role in regulating the immune response and metabolic inflammation. In real-life diets, this means more legumes, whole grains, vegetables, fruits, nuts, and seeds.

The second mechanism is more antioxidants and phytochemicals. Plant foods contain polyphenols, carotenoids, vitamin C, vitamin E, and other compounds that can reduce oxidative stress. Oxidative stress and inflammation often reinforce each other, especially in obesity, insulin resistance, and vascular disorders.

The third mechanism is changing the diet's fat profile. Plant-based diets typically contain more unsaturated fats and less saturated fats, especially if they rely on nuts, seeds, vegetable oils, legumes, and whole foods rather than ultra-processed substitutes.

The fourth mechanism is related to body weight, blood pressure, and low-density lipoprotein cholesterol. Joshua Gibbs of Warwick Medical School noted that plant-based diets are already known to improve risk factors such as blood pressure, low-density lipoprotein cholesterol, and body weight; reducing inflammation may be another way through which such diets reduce the risk of chronic diseases.

Possible mechanism	How can it work?
More dietary fiber	Supports microbiota and anti-inflammatory metabolites
More antioxidants	Reducing oxidative stress
More unsaturated fats	More favorable lipid and inflammatory profile
Less saturated fat	Possible reduction in metabolic load
Weight loss	Reducing inflammation associated with excess fat tissue
Improving blood lipids	Potential reduction in vascular inflammation

What does this mean for the average person?

The main practical conclusion isn't that everyone should immediately go vegan. The study speaks to plant-based diets in a broad sense: more whole plant foods and less animal-based foods, especially if the diet was previously high in processed meat, saturated fat, and low in fiber.

A more reasonable interpretation is a gradual shift in diet toward vegetables, fruits, legumes, whole grains, nuts, and seeds. This approach may be more realistic than abruptly eliminating familiar foods completely, and it can also improve nutritional quality.

The quality of plant-based foods is also important. A diet consisting of sugary drinks, white bread, French fries, and ultra-processed plant foods may technically contain little animal-based food, but it won't be the model typically used in research on healthy plant-based eating. The benefits stem primarily from whole foods, fiber, and high nutrient density.

For people with chronic illnesses, nutritional deficiencies, pregnancy, advanced age, or following a strict vegan diet, an individualized dietary assessment is essential. The more restrictive the diet, the more closely one should monitor protein, vitamin B12, iron, iodine, calcium, vitamin D, and omega-3 fatty acids. This doesn't negate the potential benefits of a plant-based diet, but it does make planning it more important.

Practical step	Why is it useful?
Add legumes 3-5 times a week	A source of fiber, protein and minerals
Replace some of the meat with whole grains and legumes	Reduced saturated fat and increased fiber
Eat vegetables every day	More micronutrients and phytochemicals
Use nuts and seeds in moderation	Source of unsaturated fats
Limit ultra-processed foods	Not all plant foods are automatically healthy.
Monitoring vitamin B12 levels while on a strict vegan diet	It is a critical nutrient that is not found in reliable amounts in plant foods.

Limitations of the study

The first limitation is the small number of trials. Of the nearly 3,000 studies found, only 7 met the strict criteria for randomized controlled trials. This means the scientific base is significantly narrower than the topic's popularity might suggest.

The second limitation is high heterogeneity. The trials may have differed in the type of plant-based diet, duration, baseline health of the participants, physical activity level, calorie control, and the quality of the omnivorous diet being compared. Therefore, the overall result should be interpreted as an average of different interventions, not as the effect of one specific diet.

The third limitation is the low certainty of the evidence. The reduction in C-reactive protein appears significant, but the authors explicitly state that larger, more robust trials are needed. Studies comparing a plant-based diet not to a "regular" low-quality diet, but to a well-planned, healthy omnivorous diet, are particularly important.

The fourth limitation is that C-reactive protein is a surrogate marker. Its reduction may be a favorable sign, but it does not, by itself, prove a reduction in the incidence of heart attacks, strokes, diabetes, or cancer. Long-term clinical trials with "hard" outcomes are needed to draw such conclusions.

Limitation	Why is this important?
Only 7 tests	The evidence base is still small.
541 participants	This is a modest sample size for nutritional conclusions.
Different types of plant-based diets	You can't reduce the results to just one diet
High heterogeneity	The effect may have varied between studies.
Low certainty of evidence	Larger trials are needed
C-reactive protein is a marker, not a clinical outcome	Does not directly prove a reduction in heart attacks or mortality

Result

A new meta-analysis in Nutrition, Metabolism, and Cardiovascular Diseases shows that plant-based diets can reduce levels of C-reactive protein, a marker of systemic inflammation, by approximately 1.13 milligrams per liter compared to omnivorous diets. This may be significant because chronic low-grade inflammation is associated with aging, cardiovascular disease, type 2 diabetes, and several other chronic diseases.

The study's greatest strength is its focus on randomized controlled trials, rather than solely observational data. This makes the conclusion about a possible anti-inflammatory effect of a plant-based diet more compelling than a simple association from population studies.

The biggest weakness is the small number of high-quality trials. Of the nearly 3,000 publications found, only 7 were included in the meta-analysis, and the authors explicitly state the need for larger studies. Therefore, this news shouldn't be interpreted as definitive proof that any plant-based diet automatically reduces inflammation in everyone.

The correct formulation is this: a plant-based diet, especially one based on whole foods, may be one way to reduce systemic inflammation and improve cardiometabolic health, but the optimal effect likely depends on diet quality, physical activity, body weight, and baseline health.

News source: Bell L., Gibbs J., Cappuccio FP The effect of plant-based dietary patterns on C-reactive protein: A systematic review and meta-analysis of randomized controlled trials. Nutrition, Metabolism and Cardiovascular Diseases. 2026. DOI: 10.1016/j.numecd.2026.104631.