One-month clinical trial links vegan diet to slower biological aging

A month-long trial on a vegan diet reveals positive epigenetic changes underpinned by reduced inflammation and biological aging markers. The study evidences the impact diets have on molecular biology, suggesting that dietary composition is more important than calorie reduction alone. 

Randomized clinical trial participants following a vegan diet showed significant DNA methylation changes linked to immune function and metabolism compared with those on a meat-rich diet, according to the researchers from the University of California (UC) San Diego (US) and the University of Freiburg (Germany).

DNA methylation is a biological process that regulates whether genes are more or less active.

“Our study adds to growing evidence that nutrition can shape biology at the molecular level,” says co-senior author Max Storz, M.D., researcher at the University of Freiburg Medical Center.

The team cautions that the study was small and only lasted for a month. Storz says: “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.” 

Genes are not destiny

The publication in MedComm explains the importance of diet, as it has been linked to risks of chronic diseases. However, scientists are only beginning to understand how food influences the epigenome. These chemical changes can help determine which genes are turned on or off without changing the DNA sequence.

“Our genes are not our destiny,” states study co-senior author Jerome Mertens, Ph.D., associate professor of neurosciences at UC San Diego School of Medicine. 

The findings add to previous evidence that plant-based diets influence the immune function, while bringing new insights into its molecular changes.“The remarkable finding isn’t simply that one diet outperformed another. It’s that the epigenome responded measurably in just four weeks, showing that our biology is far more dynamic — and responsive to everyday choices — than we often assume.”

Detecting real changes

To explore the effects of epigenome changes, the team analyzed genome-wide DNA methylation patterns in blood samples from 48 healthy adults. These participants followed the same standardized diet for one week and were then randomly assigned to a vegan or meat-rich diet.

Both the diets were designed to provide similar calorie intake, enabling the researchers to understand the effects of diet composition rather than weight loss. 

Based on analysis of over 800,000 methylation sites across the genome before and after the intervention, the researchers predicted lower proportions of neutrophils, which are immune cells that drive inflammation. The analysis also predicted high levels of CD4 T cells that help regulate immune responses.

“That agreement told us we weren’t just seeing changes on a computer screen — we were detecting real and meaningful biological changes,” comments study first author Lukas Karbacher, a neuroscience graduate student at the UC San Diego School of Medicine.

These findings add to previous evidence that plant-based diets influence the immune function, while bringing new insights into its molecular changes.

The study additionally links the vegan diet to increased promoter methylation, which reduces gene activity that involves cancer-related and cell growth pathways.

Furthermore, the team noted reduced activity in lipid metabolism pathways and increased pathway activities related to insulin signaling, DNA repair, and cellular stress responses.

Designing clocks

The most striking finding was regarding biological aging, according to the researchers. They measured this using epigenetic clocks, which are mathematical biomarkers that predict biological age based on DNA methylation patterns rather than years lived. 

Two clocks were designed to predict health outcomes, showing the vegan diet group had slower biological aging. The third clock, which was developed to predict chronological age, showed that epigenetic aging measures different aspects of aging.

“These findings reinforce the idea that not all measures of biological aging capture the same biology,” says 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.”

In related news on biological aging, recent observational research found that higher levels of circulating vitamin D showed slower biological aging.

Omega-3 came under the spotlight as the industry is entering a fermentation-driven phase, enabling scalable, sustainable production while expanding applications into longevity, cognition, and personalized nutrition.