Major review finds plant-based diets may lower inflammation more than omnivorous diets

Plant-based diets provide anti-inflammatory effects that persist without exercise, but are amplified when combined with physical activity for maximum chronic disease protection. 

Researchers at the University of Warwick, UK, analyzed seven randomized controlled trials involving 541 participants, finding that plant-based diets significantly reduced CRP levels compared to omnivorous diets. 

Lead author Luke Bell, a student at Warwick Medical School, shares: “We found that consuming a plant-based diet instead of an omnivorous diet reduced CRP levels by 1.13 mg/L on average. CRP is one of the body’s main signals of inflammation, and lower levels generally indicate less background inflammation circulating in the body.”

The research team notes that plant-based diets are rich in beneficial nutrients, which could contribute to their anti-inflammatory effects. 

Additionally, previous observational research has linked plant-based diets to lower levels of inflammation and reduced risk of chronic disease. However, earlier reviews largely relied on this observational evidence, whereas the new review exclusively looked at randomized controlled trials — regarded as the gold standard for establishing cause and effect.

Co-author and professor of Cardiovascular Medicine & Epidemiology, Francesco Cappuccio from Warwick Medical School, adds: “Although the results suggest a plausible effect of plant-based food in reducing inflammation, given the paucity of large trials, we should encourage more robust evidence to support these early findings.”

Strict study selection

The paper in Nutrition, Metabolism and Cardiovascular Diseases points out that chronic low-grade inflammation, also known as “inflammaging,” is increasingly being found to drive age-related diseases. It is also seen in conditions including cardiovascular disease, type 2 diabetes, and some cancers.

The researchers highlight that out of the initial 3,000 studies identified as measuring plant-based diets and CRP, only seven met the strict criteria for inclusion as randomized controlled trials. This selection of plant-based dietary patterns included vegan, vegetarian, and whole-food plant-based diets and were linked to significantly lower CRP levels.

“CRP levels are also commonly used to assess cardiovascular risk, with levels below 1 mg/L considered low risk and above 3 mg/L high risk. Therefore, a CRP reduction of the magnitude found in our study could move individuals into lower risk categories,” says Bell.

Lifestyle and diet impacts

Plant-based diets are often high in fruits, vegetables, whole grains, legumes, nuts, and seeds. People on these diets also tend to consume higher levels of fiber, antioxidants, and unsaturated fats than diets that include more animal products. The team believes that the anti-inflammatory effect could partly be aided by these benefits.

Recent research found that older adults consuming a polyphenol-rich diet showed significant reductions in pro-inflammatory markers, including interleukin-6 and CRP. Another paper found that cocoa extract supplements, rich in flavanols, may reduce inflammation and prevent age-related chronic diseases.

Warwick co-author and project supervisor Joshua Gibbs says: “Plant-based diets are already known to improve key cardiovascular risk factors such as blood pressure, LDL cholesterol, and body weight. Our findings suggest an additional pathway through which these diets may reduce chronic disease risk.”

“When studies that included structured exercise programs were excluded, the reduction remained, although slightly smaller. The largest reductions were seen in studies that combined plant-based diets with increased physical activity, suggesting lifestyle changes may have the greatest impact when adopted together, although more research is needed to confirm this.”