In a study that involved pairs of identical twins, Stanford scientists have shown that a healthy vegan diet leads to a decrease in biological age and possibly to other health benefits [1].
Do you really live longer if you eat well?
A good diet can do wonders for health, but it is still unclear if it actually promotes longevity. Populational studies have found that a healthy diet can decrease the risk of getting cancer, cardiovascular diseases, and type 2 diabetes, and it is associated with lower mortality [2]. However, this is not exactly the same. Proper lifespan studies in humans are complicated by us being an exceptionally long-lived species.
To overcome this limitation, scientists have come up with biological clocks: single or composite biomarkers that supposedly show the body’s physical rate of aging. The difference between a person’s chronological and biological age is that person’s age acceleration.
One of the most popular types of biological clocks uses DNA methylation, the addition of a methyl group to the nucleotides that compose DNA [3]. DNA methylation patterns correlate with chronological age and mortality amazingly well, although the mechanism behind this correlation is not fully understood.
This new study, led by researchers from Stanford University and the company TruDiagnostics, might be the first to compare the effects of a wholesome vegan diet to a wholesome omnivorous diet on age acceleration as measured by methylation clocks. Moreover, the researchers used pairs of twins, which allowed them to automatically control for genetic, age, and sex differences.
Vegans age slower
Generally healthy twins in 21 pairs were put on either a vegan or omnivorous diet for eight weeks. The researchers tried making the diets as healthy as possible, such as by avoiding ultraprocessed food.
For their analysis, the scientists used multiple well-established methylation clocks, such as the second-generation blood and skin Horvath clock, GrimAge, PhenoAge, and DunedinPACE. They also calculated the individual ages of 11 organs and systems (heart, lung, kidney, liver, brain, immune, inflammatory, blood, musculoskeletal, hormone, and metabolic) along with their composite: Systems Age.
At the end of the experiment, GrimAge, PhenoAge, and DunedinPACE showed a marked decrease in average age acceleration in the vegan cohort but not in the omnivorous cohort. Interestingly, the most significant decrease was clocked by DunedinPACE, which is specifically designed to measure epigenetic age acceleration. Significant biological age reductions were also observed exclusively in the vegan cohort for 5 out of these 11 systems (inflammation, heart, hormone, liver, and metabolic) as well as for System Age.
Telomeres and other metrics
Because of its status as a hallmark of aging, the researchers also measured telomere length. By the end of the eighth week, the vegan group had significantly longer telomeres than the omnivorous group.
The difference in diet did not induce profound changes in the relative abundance of various immune cells. Among 12 immune cell subtypes, only basophil levels increased slightly in the vegan group and dropped even more slightly in the omnivorous group. Basophil abundance is related to inflammation, and the researchers cautiously note that their finding “contrasts with studies emphasizing the immunomodulatory benefits of plant-based diets.”
While genetic differences are commonly associated with an increased or decreased risk of various conditions, certain methylation changes show similar correlations. The researchers analyzed two methylation loci associated with type 2 diabetes. The vegan diet produced pro-diabetes changes in methylation in one locus, and anti-diabetes changes in the other.
Another novel approach in this study was the use of epigenetic biomarker proxies (EBPs), epigenetic values that correlate with certain biomarkers instead of the biomarkers themselves. For example, the EBP for C-reactive protein, the most popular marker of inflammation, was significantly lower in the vegan group. This is consistent with previous research that has tied a vegan diet to lower inflammation.
This study had multiple limitations, most notably a small sample size and a short intervention duration. It would be interesting to see the effect of a vegan diet on the epigenome over a longer period. Yet, the results sit well with the growing evidence that vegan diet, when properly done, confers significant health benefits.
In this study, we sought to elucidate the impact of a “healthy vegan” or a “healthy omnivorous diet” on epigenetic age, telomere length, immune cell subsets, and type 2 diabetes (T2D) risk-associated CpGs, building on current knowledge of nutrition on both diets. Our findings reveal distinct responses to vegan and omnivore diets, aligning with existing literature on the subject. Notably, the vegan cohort exhibited a significant decrease in epigenetic age acceleration, as demonstrated by reductions in multiple epigenetic aging clocks.
Literature
[1] Dwaraka, V. B., Aronica, L., Carreras-Gallo, N., Robinson, J. L., Hennings, T., Carter, M. M., … & Gardner, C. D. (2024). Unveiling the epigenetic impact of vegan vs. omnivorous diets on aging: insights from the Twins Nutrition Study (TwiNS). BMC medicine, 22(1), 301.
[2] Shan, Z., Wang, F., Li, Y., Baden, M. Y., Bhupathiraju, S. N., Wang, D. D., … & Hu, F. B. (2023). Healthy eating patterns and risk of total and cause-specific mortality. JAMA internal medicine, 183(2), 142-153.
[3] Bell, C. G., Lowe, R., Adams, P. D., Baccarelli, A. A., Beck, S., Bell, J. T., … & Rakyan, V. K. (2019). DNA methylation aging clocks: challenges and recommendations. Genome biology, 20, 1-24.
