Short-term vegan diet may slow aging, but questions remain

Following a vegan diet for a couple months may slow aging, new research hints.

However, these findings shouldn't be overhyped, experts cautioned, in part due to limitations in how the study was conducted.

In a small clinical trial that included 21 pairs of healthy identical twins, one twin from each pair ate a vegan diet while the other twin followed an omnivorous diet, which included plants, meat, eggs and dairy. The twins followed these diets for eight weeks. The idea behind using identical twins is that, given their shared genetics, the influence of diet can then be isolated and studied more easily.

The twins, who were around 40 years old on average and mainly women, ate meals the researchers prepared for them for the first month of the study. For the second month, the participants cooked for themselves, after receiving nutrition classes.

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The researchers analyzed the participants' blood before they started their diets, four weeks in, and then again at the end of the study. They looked for changes in the chemical tags on top of DNA within the twins' cells; specifically, they assessed molecules called methyl groups, which latch onto DNA and change the extent to which specific genes are "switched on." They do this without altering the underlying DNA code — a phenomenon known as epigenetic modification.

Changes in methylation patterns are associated with accelerated rates of aging, and scientists have previously studied these changes in order to make "epigenetic clocks" that can be linked to organisms' maximum life spans.

At the eight-week mark, the twins who ate a vegan diet had significantly reduced levels of DNA methylation, compared to before they started the study, the researchers found. Their omnivorous siblings, however, showed no significant changes in DNA methylation during this time.

The team used established tests to see if the methylation changes seen in the vegan group were tied to any specific aging processes. They found they were tied to "younger" scores for organs like the heart and liver, as well as bodily processes including inflammation and metabolism. At least one of the tests that they used is licensed by TruDiagnostics, an epigenetics testing company that also funded the new study.

These findings suggest that going vegan could have anti-aging effects, at least in the short term, the team said. They described their research in a study published Sunday (July 28) in the journal BMC Medicine.

"This trial suggests that a healthy plant-based diet may be superior to a healthy omnivorous diet in changing epigenetic markers that are potentially related to improved healthspan," Dr. Luigi Fontana, a professor of medicine and nutrition at the University of Sydney who was not involved in the research, told Live Science in an email. ("Healthspan" refers to the amount of time a person remains healthy during their life, rather than just alive.)

However, the new findings should be treated with caution, Fontana noted.

Firstly, the study was only two months long, which raises the question of whether these epigenetic changes are temporary, Fontana said. Aging is a lifelong process, so future studies would need to investigate whether these findings can be replicated in the long term, he said.

Another potential caveat of the study is that the twins who followed the vegan diet lost around 4.4 pounds (2 kilograms) more than the omnivores. This is because they were eating substantially fewer calories, lead study author Varun Dwaraka, head of bioinformatics at TruDiagnostics, told Live Science. As such, it could be that these weight changes somehow contributed to the observed changes in DNA methylation.

Notably, calorie restriction has been shown to slow aging in mice and in monkeys, as well as in some early clinical trials in humans.

"What we would hope for in the next analysis is to start to disentangle these aspects," Dwaraka said. Future trials could ensure that the participating twins consume the same amount of calories, regardless of their diet, he said.

Going vegan not only affected measures of biological aging but also changed the types of immune cells circulating in the participants' blood, said Daniel Belsky, an associate professor of epidemiology at Columbia University. Belsky was involved in the development of one of the epigenetic tests used in the study but not in the study itself.

The measures of biological aging were taken from immune cells, so what appears to be an effect of a vegan diet on aging could be an "artifact" of a short-term immune response to this way of eating, Belsky told Live Science in an email.

Nevertheless, the new study suggests that epigenetic tests can help estimate how different diets affect the aging process, Dwaraka said. Going forward, the team plans to investigate whether following other diets — such as keto or paleo diets, for instance — could produce similar anti-aging benefits.

This article is for informational purposes only and is not meant to offer medical advice.

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