July 29, 2024

expert reaction to study suggesting short-term vegan diet is associated with reductions in biological age estimates

A study published in BMC Medicine looks at short term vegan diets and ageing. 

Prof Tom Sanders, Professor emeritus of Nutrition and Dietetics, King’s College London (KCL), said:

“This is a small study conducted in twins one of whom was allocated to a vegan diet and the other to a mixed diet for 2 months. Measurement of some biological markers of ageing such as telomere length and methylation of DNA were made. The report found some difference which might be favourable in terms of ageing for vegans. However, this assertion does not consider the fact that micronutrient deficiencies often take years to exert harmful effects. For example, unless a vegan diet is supplemented with vitamin B12 they develop vitamin B12 deficiency that causes chronic and often insidious damage to the nervous system. Long-term observational studies of vegans also find adverse effects on bone density that is probably caused by very low calcium and marginally adequate protein intakes. 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.”

Dr Duane Mellor, Dietitian and Spokesperson for British Dietetic Association; and Honorary Academic Fellow at Aston University, British Dietetic Association (BDA), said:

“This is a follow up study to one published In November 2023 in JAMA Open and was commented upon in the Science Media Centre at the time, this study has the same limitations, in that those following the vegan diet ate fewer calories and lost weight which could easily be the reason why the participants DNA was methylated in a healthier way that is associated with longevity.

“This is an interesting study which considered the effect of two diets on how the DNA can be changed over an eight week period, one group followed a vegan diet and the other a mixed or omnivorous diet. The authors found that changes in how the DNA was methylated, a normal way DNA is changed in response to the environment including diet on a vegan diet could possibly be linked to cells ageing more slowly. However, there were no changes in how quickly cells divided or died, again a normal part of our biology, but if out of control can be linked to diseases such as cardiovascular disease or cancer.

“Although the study compared a vegan diet to an omnivorous diet, these diets were not entirely matched with vegan participants on average consuming around 200kcal fewer per day, resulting in an average 2 kg weight loss. This was generally caused by those on the vegan diet eating less protein and fat than the omnivore group. It is possible that a reduction in energy intake could potentially have altered how the participants DNA was changed. Another important consideration was that the vegan group were asked to eat twice the number of portions of vegetables, more fruit and more legumes, nuts and seeds than the omnivore group. In part this was to replace meat, eggs and dairy foods, but this would mean fibre intake as well as the vitamin and mineral intakes are likely to be different between group, which also could in part explain the differences reported. Finally, the omnivores were asked to eat 6-8oz ( 175-225g) of meat per day, which seems a lot compared to the UK recommendations (although this was total meat and not just read meat) of 70-90g per day.

“Overall, the benefits in terms of altering DNA methylation are theoretical, and not directly linked to living longer and the changes due to the diet could be down to the vegan group eating more plants and not that a vegan diet is healthier than a mixed diet. The key for any diet with or without animal products is that it is made up of a wide range of foods, including vegetables, fruits, nuts, seeds, beans, peas and lentils with wholegrain and if you want to consume them moderate amounts of meat and dairy. If you do not wish to consume animal products then alternative sources of nutrients including iodine, iron, calcium along with vitamins B12 and D need to be included in your diet along with a source of omega 3 fatty acids.”

‘Unveiling the epigenetic impact of vegan vs. omnivorous diets on aging: insights from the Twins Nutrition Study (TwiNS)’ by Varun B. Dwaraka et al. was published in BMC Medicine at 01:00 UK time on Monday 29 July 2024.

DOI: 10.1186/s12916-024-03513-w

Declared interests

Dr Duane Mellor: I have discussed and been a consultant about the concept of UPF for EUFIC, APPGs (both unpaid as part of my previous academic role) and members of the food industry (including Mars and Danone as a paid independent consultant). I also feel it appropriate to state I follow a vegetarian diet, but support people to follow the dietary pattern of their preference.

Prof Tom Sanders: “Member of the Science Committee British Nutrition Foundation.  Honorary Nutritional Director HEART UK.

Before my retirement from King’s College London in 2014, I acted as a consultant to many companies and organisations involved in the manufacture of what are now designated ultraprocessed foods.

I used to be a consultant to the Breakfast Cereals Advisory Board of the Food and Drink Federation.

I used to be a consultant for aspartame more than a decade ago.

When I was doing research at King’ College London, the following applied: Tom does not hold any grants or have any consultancies with companies involved in the production or marketing of sugar-sweetened drinks.  In reference to previous funding to Tom’s institution: £4.5 million was donated to King’s College London by Tate & Lyle in 2006; this funding finished in 2011. This money was given to the College and was in recognition of the discovery of the artificial sweetener sucralose by Prof Hough at the Queen Elizabeth College (QEC), which merged with King’s College London. The Tate & Lyle grant paid for the Clinical Research Centre at St Thomas’ that is run by the Guy’s & St Thomas’ Trust, it was not used to fund research on sugar. Tate & Lyle sold their sugar interests to American Sugar so the brand Tate & Lyle still exists but it is no longer linked to the company Tate & Lyle PLC, which gave the money to King’s College London in 2006.”