A new study suggests that a short switch to a vegan diet can change how genes behave in ways linked to less inflammation and slower biological ageing. The research came from teams at UC San Diego and the University of Freiburg in Germany. It was published in MedComm.
The scientists looked at DNA methylation. This is a chemical process that controls whether genes are switched on or off. It doesn’t change the DNA itself, just how active certain genes are. The study found that just four weeks on a vegan diet could shift these patterns in ways tied to immune health, metabolism, and cancer-related processes.
Lukas Karbacher, the study’s lead author, said the changes in the data closely matched real blood test results from participants. That match gave the team confidence; the effects were real, not just statistical noise.
How the study worked
Researchers recruited 48 healthy adults. First, everyone ate the same standard diet for one week. Then, they were randomly split into two groups. One group ate a vegan diet. The other ate a meat-heavy diet. Both diets had the same number of calories. This design let researchers study the effect of food type, not weight change.
The team scanned more than 800,000 spots on the genome where methylation can occur. They compared these spots before and after the one-month diet period. Instead of focusing on single genes, they looked at wider patterns across many genes at once.
Effects on the immune system
People on the vegan diet showed signs of a calmer immune system. Their methylation patterns pointed to fewer neutrophils, a type of immune cell linked to inflammation. At the same time, they had more CD4 T cells, which help keep immune responses balanced. These predictions lined up with actual blood measurements taken during the trial.
Effects on cancer-related genes and metabolism
The vegan diet also raised methylation levels in certain gene areas connected to cell growth and cancer risk. Higher methylation in these zones can lower gene activity, which may reduce unchecked cell growth. The diet was also linked to lower activity in genes tied to fat metabolism. Meanwhile, activity increased in pathways related to insulin signalling, DNA repair, and the body’s response to cellular stress.
Effects on biological aging
The most notable result involved biological age. Researchers used epigenetic clocks, which estimate a person’s biological age using methylation patterns rather than birth date. Two clocks, both built to reflect health risk, showed that vegan-diet participants aged more slowly at the biological level during the month-long study. A third clock, designed instead to track chronological age, did not show the same pattern. This shows that not all aging clocks measure the same thing.
Jerome Mertens, a UC San Diego neuroscience researcher and co-senior author, said the study’s biggest takeaway isn’t that one diet simply wins over another. Instead, he noted that meaningful biological change can happen within weeks, showing the body adapts faster than many people assume.
Limitations
The researchers were careful to note the study’s limits. It included only 48 people and lasted just one month. The methylation shifts were small and scattered across many genome locations. Larger, longer trials are needed to confirm the results and to see if they actually lower disease risk over time.
Max Storz of the University of Freiburg, another co-senior author, said the results add to growing proof that food can shape biology at a molecular level. He also stressed that the effects were not due to fewer calories but to the type of food eaten. Future research, he said, needs to check whether these changes last and whether they lead to real long-term health benefits.
