“That agreement told us we weren’t just seeing changes on a computer screen — we were detecting real and meaningful biological changes,” said Lukas Karbacher, UC San Diego School of Medicine neuroscience graduate student and first author of the study.
The findings build on earlier evidence that plant-based diets can influence immune function while providing additional insight into the molecular changes that accompany those effects.
In addition to immune signals, the researchers found that the vegan diet was associated with increased promoter methylation in genes involved in several cancer-related and cell growth pathways. Increased promoter methylation can reduce the activity of genes within these pathways, suggesting the diet may influence cellular processes involved in growth and proliferation. The researchers also observed changes consistent with reduced activity in lipid metabolism pathways and increased activity in pathways related to insulin signaling, DNA repair and cellular stress responses.
Perhaps the most striking finding concerned biological aging itself. For this, the researchers examined biological age using epigenetic clocks — a mathematical biomarker that estimates a person’s biological age based on DNA methylation patterns rather than years lived. Two clocks designed to predict health outcomes suggested participants following the vegan diet experienced a deceleration in biological aging over the one-month study period. A third clock, optimized to predict chronological age rather than health outcomes, showed a different pattern, highlighting that epigenetic clocks measure different aspects of aging.
“These findings reinforce the idea that not all measures of biological aging capture the same biology,” said Mertens. “The clocks associated with disease risk and overall health consistently pointed in the same direction, suggesting the dietary changes were influencing pathways tied to health rather than simply the passage of time.”
The researchers caution that the study was relatively small, involving 48 healthy adults, and lasted only one month. Because the observed DNA methylation changes were modest and spread across hundreds of thousands of sites in the genome, larger and longer studies will be needed to confirm the findings and determine whether the molecular changes translate into measurable reductions in disease risk.
While the findings do not demonstrate that a vegan diet prevents cancer or reverses aging, they provide new insight into how dietary choices may rapidly influence the biological processes that underlie inflammation and age-related disease.
“Our study adds to growing evidence that nutrition can shape biology at the molecular level,” said Max Storz, MD, from University of Freiburg Medical Center and co-senior author of the study. “The next step is to understand whether these epigenetic changes persist over time and whether they translate into meaningful improvements in long-term health. That will require larger clinical studies, but these findings provide an important foundation.” Storz also stressed that the findings are not the result of reduced calories, but rather a matter of diet composition.
Read the full study: [A vegan diet epigenetically modulates inflammatory pathways and biological aging: Genome-wide DNA methylation analysis of a one-month isocaloric vegan versus meat-rich dietary intervention]
Additional co-authors on the study include: Stefanie Kowarschik, Manching Ku and Roman Huber at University of Freiburg Hospital; and Ann-Kathrin Lederer, University Medical Center of the Johannes Gutenberg University Mainz.
The Ministry of Science, Research and Arts of the state Baden-Württemberg, Germany, financed the position of Lederer within the Academic Center for Complementary and Integrative Medicine (AZKIM), otherwise the study was financed by institutional resources.
The authors declare no conflicts of interest.
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