Limiting your diet to only plant foods can lower your biological age, or so one study suggests.
Researchers at Stanford University in California tested twins and found that those who followed a vegan diet for two months had fewer signs of aging in their DNA than those who followed an omnivorous diet.
However, independent experts warn that the findings may not be entirely accurate and that cutting out animal products could lead to all kinds of deficiencies in the long term.
They pointed to a range of factors and shortcomings in the research that could explain or influence the findings.
They also pointed out that other studies have shown that vegans do not have a longer life expectancy than omnivores.
While eating more vegetables has a host of benefits, avoiding meat, fish, eggs and dairy products in the long term can increase your risk of nutritional deficiencies, warns Tom Sanders, emeritus professor of Nutrition and Dietetics at King’s College London.
Professor Tom Sander, an expert in nutrition and dietetics at King’s College London, was one of the experts who raised problems with the study’s findings that veganism slows biological ageing.
He pointed out that the relatively short follow-up period of just two months could not take into account the damage that long-term veganism can do to the body.
“For example, if a vegan diet is not supplemented with vitamin B12, a vitamin B12 deficiency will develop. This will lead to chronic and often insidious damage to the nervous system,” he said.
‘Long-term observational studies among vegans also show negative effects on bone density, likely caused by very low calcium and marginally adequate protein intake.’
Vitamin B12 is needed for healthy blood and a healthy nervous system.
It is common in meat, fish and dairy products, so most people do not need to worry about it. However, vegans are at risk of deficiency.
Calcium, a rich source of calcium is dairy, on the other hand is vital for maintaining healthy bones and teeth. A deficiency can lead to brittle bones.
Professor Sander added that deficiencies are particularly concerning for older vegans, who may develop serious health problems as a result of their diet.
‘Although observational studies show that a vegan diet can have beneficial 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 appear to be more likely to experience muscle loss, low bone density and neurological disorders, which have a significant impact on quality of life,’ he said.
He added that other research had shown that vegans did not experience any increase in their overall lifespan compared to omnivores.
“The life expectancy of vegans is no different from that of people who follow a mixed diet,” he said.
Dr Duane Mellor, dietitian and spokesperson for the British Dietetic Association, added that it is important to remember that other aspects of the study could account for the observed decrease in biological support in participants following a vegan diet.
“Although the study compared a vegan diet to an omnivorous diet, these diets did not fully match the vegan participants. They consumed an average of 200 kcal less per day, resulting in an average weight loss of 2 kg,” he said.
Researchers at Stanford University in California found that volunteers who followed a vegan diet for just eight weeks showed fewer signs of aging than those who followed an omnivorous diet
‘It is possible that a reduction in energy intake influenced the way the participants’ DNA was changed.
‘Another important consideration was that the vegan group was asked to eat twice as many servings of vegetables, more fruit, and more legumes, nuts and seeds than the omnivore group.
‘This was partly intended to replace meat, eggs and dairy products, but this would mean that fibre intake and also vitamin and mineral intake is likely to differ between groups, which could also partly explain the reported differences.’
He added that the omnivorous group in the study sample was also asked to eat a significant amount of meat, which could potentially magnify the differences.
‘Omnivores were asked to eat 175-225g of meat per day, which seems high compared to the UK recommendations, although this included all meats and not just red meat, namely 70-90g per day.
Dr Mellor said the changes he saw in the participants’ DNA were generally “theoretical” and not directly linked to longer life.
He advised: ‘The key to any diet with or without animal products is that it consists of a wide variety of foods including vegetables, fruits, nuts, seeds, beans, peas and lentils with whole grains and, if you choose to consume them, moderate amounts of meat and dairy.
‘If you do not wish to consume animal products, then alternative sources of nutrients, such as iodine, iron, calcium and vitamins B12 and D, should be included in your diet, along with a source of omega-3 fatty acids.’
Professor Sanders claims older vegans are more likely to suffer from muscle loss, low bone density and neurological disorders (stock image)
The findings of the new study, published in the journal BMC Medicine, are based on a small-scale study of 21 pairs of identical twins aged 39.
One pair of each twin was fed a vegan diet, while the other pair followed an omnivorous diet.
At the end of the study, the researchers observed a decrease in estimates of biological age based on levels of DNA methylation, a type of chemical modification of DNA used to estimate biological age.
Biological aging refers to the deterioration in the functioning of tissues and cells in the body, or, in other words, the appearance of the body.
This is in contrast to chronological age, which indicates how many years old someone is.
Previous research has shown that increased DNA methylation levels are associated with aging.
The authors of the new study, Varun Dwaraka of the epigenetic testing company TruDiagnostic Inc. and Christopher Gardner of Stanford University in California and colleagues, also acknowledge that their findings have limitations.
According to them, it is unclear to what extent the differences between the couples can be attributed to differences in diet.