Bengaluru: Being on a vegan diet can slow down biological ageing and changes to DNA, a small new study based on 21 pairs of identical twins has shown.
A US team of researchers studied the effects of a short-term vegan diet by having one half of each pair of twins eat an omnivorous diet, and the other a vegan diet, for eight weeks.
Subsequent study of the impact of diet on DNA showed lowered DNA methylation, a process where gene expression degrades over time, on a non-vegan diet. This is known as epigenetic ageing, and was observed to be lower in metabolic and inflammatory systems, as well as organs like heart, liver, etc., among vegan dieters.
The data from this twins’ nutrition study (TwiNS) on geroscience (study of ageing) was published in the journal Biomedical Central Medicine Monday.
The authors, however, caution that the findings of the study be interpreted better after follow-up studies on larger populations. A confounding factor for the study was that those on a vegan diet lost on average 2 kg more than their respective omnivorous twin. Weight loss is also associated with lowered epigenetic ageing.
Additionally, the authors also concluded that a vegan diet resulted in lowered caloric intake.
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Ageing studies
In recent years, large advances in biomedical technology have enabled researchers to begin investigating the molecular mechanisms behind the process of ageing.
The authors state in their paper that this is crucial as ageing is associated with significant increases in healthcare costs and financial stress on average.
While many studies focus on lifestyle changes, sleep and social factors, the molecular effects of food intake and diet are not fully understood at a genetic level. Frequent findings show that a mediterranean diet — comprising mainly fruits, vegetables, grains, fats and fish — is ideal for longevity at a molecular level.
As our bodies age, a process called DNA methylation takes place in our genes where methyl group carbon molecules get added to the DNA. This does not physically change the DNA, but changes the way genes are expressed or carry out functions. This is called an epigenetic change, where the outside environment changes the way a gene is expressed without modifying it, and is associated frequently with lifestyle changes.
Certain patterns of DNA methylation have been identified, and are called epigenetic clocks. These are used to estimate biological age and estimate age-related outcomes later in life.
Twins in study
The twin pair study was performed in 2022, over eight weeks, with 21 pairs of healthy identical twins. Sixteen pairs of these twins were women, and the average age was 40. Identical twins have identical genetics, making changes in comparison more granular and accurate.
The study was split into two four-week phases. The omnivorous group ate meat, eggs and dairy, while the vegan group ate only plant-based foods. The participants were regularly surveyed for fatigue, physical activity, stress and general health.
Blood samples for DNA analysis were collected at the four-week mark, and the eight-week mark for comparison.
The team calculated individual ages of 11 organ systems — heart, lung, kidney, liver, blood, brain, immune, inflammatory, musculoskeletal, and metabolic. Additionally, several other well-understood biological epigenetic ageing clocks were also measured.
In the omnivorous cohort, there were no significant changes in epigenetic age methylation, but it was widely observed in those on the vegan diet, where age acceleration seemed to have slowed.
Additionally, the authors also noticed an increase in basophils, a type of white blood cells associated with immunity, increasing the body’s defences against parasites and bacteria.
But on the contrary, among the omnivore group, the team found an increase in serotonin, present in plenty in animal foods, indicating better mood regulation. Similarly, adenosine, which promotes sleep and reduces anxiety, showed an increase in the omnivore group.
The authors warn that vegans and vegetarians are prone to developing a risk of vitamin B12 deficiency.
At the end of eight weeks, the vegan group had consumed on average 200 calories less per day than the omnivore group, and had an average weight loss of 2 kg more than the omnivore group. However, while some in both groups lost weight from the strict diet, only the vegan group exhibited lowered ageing.
Within the diet itself, the vegan group consumed less saturated fats, more polyunsaturated fats, and more fibre, than the omnivorous groups, and the authors state that these need investigation for better understanding.
The study paper concludes by saying that further studies are needed for long-term assessment and health outcomes, and the role of diet and weight loss in changes to DNA methylation and biological age.
(Edited by Nida Fatima Siddiqui)
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