A vegan diet can slow signs of aging at a molecular level in as little as eight weeks, according to new research from the Stanford Twin Study.

Published in BMC Medicine, the study explores the impact of dietary patterns on biological aging by comparing identical twins who follow different diets—one vegan and the other omnivorous.

The study involved 22 pairs of adult identical twins over an eight-week period. Half of the twins (one from each pair) were randomized to a “healthy vegan” diet, while the other half consumed a “healthy omnivorous” diet.

Researchers found that twins on the vegan diet not only experienced improvements in weight, cholesterol levels, and insulin sensitivity but also showed significant changes in epigenetic markers, suggesting a younger biological age compared to their omnivorous counterparts.

Biological age is different from chronological age. Chronological age is just how many years you’ve been alive. Biological age shows how old your body seems based on its health, which can be figured out by checking things like how well your organs work, signs of inflammation, how your body processes energy, and changes to your DNA.

Initial study published in November 2023 supported the short-term benefits of a plant-based diet protocol.

The study was conducted in two phases. In the first half, twins were provided meals by a national meal delivery service, ensuring dietary consistency. In the second phase, participants took on the responsibility of preparing their own meals, adhering to the same nutritional standards set in the first phase. This shift was designed to test the sustainability and practicality of maintaining such diets in a more typical, everyday setting.

Highlighting the importance of dietary quality, Christopher Gardner, PhD, pointed out the broad spectrum covered by terms like ‘vegan’ and ‘omnivore.’ He cautioned that these categories could include unhealthy options—such as sodas, certain types of French fries, and Oreo cookies, which, while technically vegan, do not contribute to a healthful diet. To counteract this, both groups were guided to focus on diets high in vegetables and fiber and low in refined grains and sugars.

Researchers employed the Healthy Eating Index, a validated metric that uses a scoring system to assess the overall nutritional value of an individual’s diet. This tool helped ensure that both diet plans met high standards of healthfulness.

The twin-study design was pivotal, as it allowed researchers to control one of the most significant confounding factors in genetic studies—DNA variability. By comparing genetically identical twins consuming different diets, the study could directly observe the effects of diet on epigenetic markers without genetic differences clouding the results.

The study underscores that adopting a vegan diet not only confers numerous health advantages but also significantly enhances epigenetic markers linked to aging. These markers are akin to biological clocks hidden within our DNA, indicating that our biological age, which can deviate from our chronological age, is influenced by lifestyle choices, such as diet and physical activity.

To accurately gauge biological age, researchers utilized multiple diagnostic tests, including GrimAge and DunedinPACE, which assess patterns in DNA methylation—a process that impacts gene expression. Surprisingly, Varun B. Dwaraka, PhD, the lead researcher, noted that among the numerous markers analyzed, approximately twelve showed consistent reductions in epigenetic age for individuals on a vegan diet, a stark contrast to the static measurements observed in their omnivorous counterparts. This discovery was unexpected and suggests a significant impact of a vegan diet on aging at a genetic level.

Epigenetics studies how behaviors and environments influence gene function without altering the DNA sequence itself. Essentially, it acts like software that changes how the DNA ‘code’ is read, without changing the hardware, or the DNA itself. Dr. Dwaraka uses a computer analogy to explain this: the same computer can run different processes depending on the software it uses.

These changes in gene expression can affect our susceptibility to diseases and overall health. While our DNA sequence doesn’t change, our epigenetic settings can, influenced by our daily activities, affecting our biological age—a measure of cell function relative to chronological age. This is significant as humans live longer, and we continue to advance our understanding of genetics.

While the study provides intriguing insights, the authors note that their findings are only based on an eight-week timeframe and do not reflect the long-term effects of the diets studied. They plan to conduct more extended trials in the future.

Despite the short duration, the study aligns with existing knowledge that a plant-based diet has potential benefits for biological aging and overall health, particularly cardiac health.