An 8-week short-term vegan diet may help reduce biological age

• Vegan, plant-based diets are rich in fiber, antioxidants, and plant compounds that support gut health, reduce inflammation, and promote healthy metabolic processes.
• A recent study in identical twins suggests that following a healthy vegan diet for even a short period may reduce biological age estimates.
• While a vegan diet may benefit the body’s biological clock in the short term, experts still recommend balanced approaches, such as the Mediterranean diet, for long-term health.

A recent study compared the effects of an eight-week vegan diet versus an omnivorous diet on biological age estimations, which gauge overall health and the risk of age-related diseases like heart disease and Alzheimer’s.

Researchers estimated biological age by measuring DNA methylation levels— epigenetic (chemical) changes that influence gene expression without altering DNA.

Earlier studies have linked higher DNA methylation levels to aging.

The diet intervention trial, which involved 21 pairs of identical twins, suggests that adopting a vegan diet may significantly lower biological age estimates in a relatively short timeframe.

These results are consistent with previous evidence indicating that plant-based diets could offer anti-aging benefits . However, the study’s lead authors, along with external experts, urge caution in interpreting these findings due to the small sample size and limited duration.

Published in BMC Medicine and featured in Netflix’s docuseries “ You Are What You Eat: A Twin Experiment ” (2024), the findings encourage a deeper exploration of how diet and lifestyle choices impact health at a genetic level.

The epigenetic impact of vegan vs. omnivorous diets on aging

Researchers at Stanford Prevention Research Center and TruDiagnostic , a leading lab in epigenetic testing and research, aimed to identify how a vegan diet affects human biological age and health compared to an omnivorous diet.

They initially recruited 22 generally healthy adult identical twin pairs from the Stanford Twin Registry and other sources.  One twin pair was later removed for not adhering to study conditions, resulting in 21 twin pairs (42 individuals) for the final analysis.

Participants were predominantly women (77%), with an average age of 40 and an average body mass index (BMI) of 26.

After baseline assessments, one twin from each pair was randomly assigned to follow either a healthy plant-based vegan diet or a healthy omnivorous diet for eight weeks. The study comprised two four-week phases: the first with meals provided by Trifecta Nutrition tailored to their diet, and the second with self-prepared meals guided by health educators.

The omnivorous group was given daily targets for eating animal products, like meat, eggs, and dairy, while the vegan group completely avoided all animal products.

Researchers monitored dietary habits through surprise 24-hour recalls and participant food logs, ensuring data quality with interviews conducted by registered dietitians.

The study assessed how diet influences blood DNA methylation and epigenetic aging across various organ systems. Utilizing advanced analytical methods at TruDiagnostic, the researchers uncovered diet-specific shifts in clinical, metabolic, and protein markers.

Vegan diet linked to reductions in biological age estimates

The twin-pair study design controlled for genetic, age, and sex variations, highlighting the significant dietary influences on DNA methylation changes.

Over eight weeks, participants following a vegan diet showed significant reductions in their epigenetic age, while those on an omnivorous diet did not.

Only those participants who adhered to a vegan diet for eight weeks demonstrated a decrease in the biological ages of five organ systems, including the heart, hormonal, liver, inflammatory, and metabolic systems.

The researchers also observed favorable changes in markers, such as a decrease in C-reactive protein levels within the vegan group, indicating a potential reduction in systemic inflammation.

The omnivorous diet, too, showed shifts in key metabolic markers, including an increase in tryptophan—an amino acid found in animal proteins—which can raise serotonin levels and may influence mood regulation.

Ultimately, the study revealed unique DNA methylation changes associated with each diet, with only the vegan diet specifically leading to beneficial methylation changes that may contribute to reduced biological age.

Lead study author Varun Dwaraka, PhD , director of Bioinformatics at TruDiagnostic, told Medical News Today that, overall, “these results were surprising, even among interventions using epigenetic tests.”

He elaborated that in other studies using epigenetic clocks, noticeable changes typically happen after 3 to 6 months. However, Dwaraka noted that they observed significant changes as early as 8 weeks and consistently across various clocks, suggesting that diet has a rapid impact on epigenetic health in the short term.

Vegan vs. omnivorous diets for optimal epigenetic aging

Raghav Sehgal , a PhD candidate in Computational Biology and Bioinformatics at Yale University, scientific advisor at TruDiagnostic, and Director of Bioinformatics at the Healthy Longevity Clinic, offered MNT his thoughts regarding the potential mechanisms through which a vegan diet may promote optimal epigenetic aging processes:

“When we look at multiple vegan diets and green Mediterranean (similar to vegan diets except for having milk in them) the common thread we see is that the epigenetic scores for inflammation, metabolic and musculoskeletal aging are all improving. In other words, these diets may be specifically targeting inflammatory and metabolic aging pathways via epigenetics in the body and slowing them down.”
—  Raghav Sehgal, PhD candidate at Yale University

Sehgal noted that while we do not yet fully comprehend how plant-based diets might influence epigenetic aging, research indicates that a vegan diet — compared to an omnivorous one — generally leads to higher consumption of fruits, vegetables, whole grains, legumes, nuts, and seeds.

This dietary pattern typically results in:

• Lower intake of saturated fat and processed foods and reduced caloric density
• Higher intake of fiber , antioxidants , phytochemicals , and increased nutrient density
• A better omega-3 to omega-6 fatty acid ratio
• Lower BMI, visceral fat , and overall body fat

He elaborated on each potential mechanism, remarking how each may contribute to a healthier gut microbiome , reduced inflammation , and optimized metabolic processes.

“At the end of the day, the exact mechanism of how these diets are providing benefits might turn out to be through multiple different pathways in the body but the fact that they are providing benefits is very clear to us,” Sehgal stated.

Is this a win for vegan diets?

Thomas M. Holland, MD, MS , a physician-scientist and assistant professor at the RUSH Institute for Healthy Aging, RUSH University, College of Health Sciences, who was not involved in the study, offered insights into its potential strengths and limitations.

“ While the use of identical twins is a significant strength, reducing genetic variability, [an] eight-week period may not be sufficient to observe long-term effects, and with only 21 pairs, the results may lack generalizability,” he told MNT.

Holland noted that the findings could be due to the vegan group’s lower caloric intake and higher fiber consumption, leading to an average weight loss of 2 kilograms more than the omnivorous group, rather than the diet type itself.

Despite these limitations, the study’s findings align with previous research showing the potential anti-aging benefits of plant-based diets . Still, further clinical research is needed to better understand the mechanisms and long-term effects.

So, “recommending a vegan diet over an omnivorous diet for longevity is a bit premature,” Holland stated, advocating for a more balanced approach to nutrition.

Lead study author Lucia Aronica, PhD , a lecturer and researcher in personalized nutrition and epigenetics at Stanford Prevention and Research Center, Stanford University, in California, had similar thoughts on whether this study was a win for vegan diets, noting the study’s limitations and suggesting that omnivorous diets, too, have been shown to have a positive effect on biological age.

“Other diets like the Mediterranean diet , which includes both plant and animal foods, have also been shown to effectively reverse epigenetic aging. Both plant foods, which are rich in beneficial phytochemicals, and animal foods, which provide essential nutrients like B12 and choline , play crucial roles in supporting our epigenome. Ultimately, many diets can enhance our epigenetic health, provided they focus on whole foods, variety, and are personalized to individual needs.”
— Lucia Aronica, PhD

“While a vegan diet shows promise, it should be considered one of many potential dietary patterns that can contribute to healthy aging, rather than a definitive solution,” Holland concluded.