A new study revealed following a vegan diet for eight weeks can help to reduce biological age. The study was a randomised controlled trial of 21 pairs of adult identical twins which was published in the journal BMC Medicine. Knowing biological age can help understand the risk of diabetes or dementia. The results revealed that the age reduction observed was based on levels of DNA methylation which is a type of chemical modification of DNA (known as an epigenetic modification) that alters gene expression but not DNA itself.

For the study, the researchers investigated the molecular effects of a short-term vegan diet. The researchers told one-half of each twin pair to eat an omnivorous diet for eight weeks which included between 170 and 225 grams of meat, one egg and one and a half servings of dairy each day and the other half to eat a vegan diet for the same length of time.

According to a report in The Telegraph, participants had an average body mass index (BMI) of 26 kilos per metre squared and 77 per cent of them were women.

For the first four weeks of the study, participants ate meals that had been prepared for them and for the second four weeks, participants ate meals that they had prepared themselves, after receiving nutrition classes.

The researchers found that there is a decrease in estimates of biological age which is known as epigenetic ageing clocks in participants who ate a vegan diet but not among those who followed an omnivorous diet. Those on a vegan diet also had decreases in the ages of the heart, hormone, liver, and inflammatory and metabolic systems. They also lost two kilograms more on average than those who ate an omnivorous diet due to differences in the calorie contents.

Varun Dwaraka, of epigenetic testing company TruDiagnostic Inc, and Christopher Gardner of Stanford University, California, and colleagues said it is unclear how much the differences between the pairs can be attributed to the differences in diet.

Tom Sanders, professor emeritus of Nutrition and Dietetics at King’s College London, who was not involved in the study, said the research found some difference in terms of ageing for vegans but does not consider the fact that vitamin and mineral deficiencies often take years to appear, according to The Telegraph report.

He added certain studies also suggest a vegan diet may not be good for the health of older people. Prof Sanders said, “Although observational studies indicate that vegan diets may have favourable effects on health in middle age (such as a lower risk of cardiovascular disease and type 2 diabetes), this is not the case in older vegans who seem more likely to suffer from muscle loss, low bone density and neurological disorders which have a significant impact on the quality of life.

“Indeed, life expectancy does not differ in vegans compared with those who select mixed diets.”

However, the researchers said that the findings were unclear and highlighted the need to investigate further the relationship between dietary composition, weight and ageing.