The study of the impact of diet in preventing unhealthy ageing and longevity is currently under study. Different approaches have been used, for example, examining whether a particular habitual diet, maintained over time, is associated with a lower risk of frailty or disability years later, or whether a dietary pattern with more plant-based foods is associated with later death compared to people who followed a different dietary pattern.
In this paper, researchers use a clinical trial to understand the impact of a purely vegetarian dietary pattern and a healthy omnivorous dietary pattern. It was conducted with 21 [pairs of] twins, so that sex, age or inherited genetic factors did not alter the comparison of intervention effects. For eight weeks, they were given food and instructions to maintain these dietary patterns. The outcome variable that approximated ageing was the degree of DNA methylation in the blood cells after the eight weeks and the calculation of an indicator called the ‘epigenetic clock’, which is able to summarise the degree of ‘ageing’ of cells by a series of measurable parameters. They found that participants who had followed a vegetarian diet had lower methylation and a lower degree of cellular ageing.

The originality of this study lies in the association of different dietary patterns with cellular markers of processes leading to cellular ageing. In this way, it confirms that diet acts by altering specific biological mechanisms that lead to better or worse ageing. However, despite the attractiveness of the conclusion, this type of work is not able to examine the effect of a vegetarian or omnivorous diet in the long term. Furthermore, to conclude that a diet is associated with healthy ageing or greater longevity, we need to see how these diets are associated with actual health problems in older people or how they are associated with dying later or later. For this, studies of large populations followed over many years (cohort studies) remain essential and the basis for making dietary recommendations to the population. This work is insufficient to recommend vegetarian diets to the population.

This research, based on a controlled clinical trial in identical twins, shows that a vegan diet can reduce biological age. Researchers looked at 21 pairs of identical twins where, for eight weeks, one twin followed a vegan diet and the other followed an omnivorous diet. During follow-up, biological age was determined using DNA methylation levels in blood samples. These analyses were performed to estimate the biological age of the participants and various body systems, such as the heart, hormonal system, liver, inflammatory and metabolic systems.

At the end of the study, those who followed a vegan diet showed a reduction in their biological age, which did not occur in those who followed an omnivorous diet. These results suggest that a short-term vegan diet may be beneficial to health and help keep us younger at the cellular level. These findings add to a growing body of evidence indicating that increased vegetable intake and reduced meat consumption have significant health benefits. Previous research has shown that plant-based diets can reduce the risk of chronic diseases and improve metabolic health. This study offers a new perspective by showing that, in addition to these benefits, a vegan diet may positively influence ageing processes at the cellular level.
There are some limitations to this study such as the small sample size and differential weight loss between the groups, which may have influenced the results obtained.