Eight-week diet significantly reduces biological age

We know diet and lifestyle play a huge role in the onset of diseases and the management of many medical conditions, but for a lot of us, making long-term changes is easier said than done. But researchers have now demonstrated that eating a plant-based diet for just two months has a significant, meaningful impact on our biological age, which is one of the key markers of health as we get older.

Scientists have looked at the "epigenetic age clock," and how diet can influence our cellular health on a micro level. While our birthdate defines our numerical, or chronological age, the state of our cells, tissues and organ systems gives us a read on our biological age. While there's little we can do about the numbers on our birthday cards changing with each passing year, we do have some control over how quickly we biologically age.

With this in mind, researchers wanted to gauge if switching to a vegan diet for a short period of time had any impact on the biological markers of age, which brings epigenetics into focus. An emerging area of research, epigenetics looks at cellular age and externally influenced gene expression, which in turn has a significant impact on our health.

“Our epigenetic processes are under exquisite control in our bodies, but they are also extremely influenced by the environment,” said Payel Sen, from the National Institute of Aging's Intramural Research Program, who wasn't involved in this latest study. “Let’s say you go to the beach and you get exposed to a lot of ultraviolet rays. Certain regions of your skin cells’ genomes are going to react to that and produce byproducts that may not be good for our skin.”

Similarly, what we eat directly impacts our epigenome, switching on and off genes that can be both beneficial or detrimental to health. This 2023 study investigated how nutrition can be used to influence gene expression to prevent and manage cardiovascular disease, cancer and other metabolic conditions. Epigenetic modifications are also involved in inflammation across many disorders, as well as obesity, osteoporosis and diabetes.

The scientists in this latest study set out to measure just how a short-term vegan diet might change the body's biological signs of aging, compared to an omnivorous lifestyle. To do so, they recruited 21 sets of identical twins, with an average age of 40, and assigned one an eight-week healthy vegan diet plan and the other a healthy omnivore diet plan over the same time frame.

The key biomarker was change in DNA methylation – the process by which a small molecule known as a methyl group is added to DNA or proteins, essentially inhibiting or triggering gene expression. It's one of the main ways epigenetic alterations are measured (others being through histone modification and non-coding RNA). DNA methylation has also been linked to the aging process, with it increasing as we get older.

What they found was that while both twins started the trial with similar baseline scores, those on the vegan diet had significant changes in the markers underpinning biological age at the eight-week mark. It builds on the results of a previous study last November which evaluated the participants' HDL-C, glucose, insulin, TMAO, vitamin B12 and weight markers for the same trial period.

"We observed significant changes using epigenetic age clocks among healthy identical twins, suggesting short-term advantageous aging benefits for a calorie-restricted vegan diet compared to an omnivorous diet," the researchers noted. "These findings are consistent with previous research highlighting the potential anti-aging effects of plant-based diets, known for their rich antioxidant content and anti-inflammatory properties."

To assess the interplay between diet and epigenetics, the researchers assessed the individual ages of 11 organ systems: heart, lung, kidney, liver, brain, immune, inflammatory, blood, musculoskeletal, hormone, and metabolic. In the vegan group, they found significant decreases in age across five – the inflammatory, heart, hormone, liver and metabolic systems – while the epigenetic clock didn't budge for the omnivores.

Overall, this plant-based cohort had lowered their biological age by an average of 0.63 years (or just over 7.5 months) in just eight weeks. There was also a decrease in each person's biological age compared to their chronological age, which equated to 0.0312 units. Essentially, this translated to these participants having biological ages lower than what you'd expect from someone of their chronological age.

There are, however, some caveats. The omnivores were required to eat between 170-225 grams (6-8 oz) of meat, one egg and 1.5 servings of dairy every day. In the first four weeks, all participants ate specially prepared meals, while they were left to their own devices in the second half of the study. The vegan group also consumed 200 calories less per day during the first four weeks of prepared meals, and at the end of the trial had lost an average 2 kg (4.4 lb) more than the omnivore group. So more research needs to be done to determine if positive epigenetic outcomes were wholly the result of diet or a side effect of weight loss.

"It is possible that a reduction in energy intake could potentially have altered how the participants DNA was changed," said Dr Duane Mellor, spokesperson for the British Dietetic Association. "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."

Interestingly, there were some key changes in neurotransmitters and metabolic markers among the omnivorous group.

"The increase in tryptophan and serotonin, a neurotransmitter synthesized from tryptophan, suggests potential impacts on mood regulation and other serotonin-mediated functions in response to increased intake of tryptophan-rich animal protein in the omnivore diet," the researchers noted. "Adenosine, a nucleoside that promotes sleep and reduces anxiety, exhibited an increase, indicating potential changes in endogenous metabolism on an omnivore diet. These findings underscore the nuanced interplay of neurotransmitter synthesis, lipid metabolism, microbial activity, and purine metabolism associated with omnivorous dietary patterns."

They add that further research is needed, particularly in relation to diet, weight and aging, as well as the long-term health impacts of a vegan diet.

Nonetheless, the study also highlights the increasing focus on personalized medicine and epigenetics as a tool in slowing the aging process. Lead author Varun Dwaraka is also the head of bioinformatics at epigenetic testing company TruDiagnostic, which is marketing its epigenetic tests as a proactive way to "reverse your aging." However, at US$499 a kit, it might be more affordable to just give up meat and dairy for eight weeks.

"These comprehensive findings underscore the complex interplay between diet, epigenetic regulation, immune function, and metabolic health, offering valuable insights for future research and personalized health interventions," the researchers concluded.

“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," Mellor added. "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.”

The research was published in the journal BMC Medicine.

Source: Springer Nature via Scimex