Finding ways to slow ageing has been a medical ambition for centuries and remains a major focus of modern research. But the answer may not depend on the latest expensive technology: scientists now believe a particular eating pattern could help reduce biological age.
Remarkably, the apparent benefits emerged in fewer than four weeks.
The findings from an Australian study, published in the journal Aging Cell, are raising hopes that the nearest thing to an elixir of youth may be found not in a laboratory or medicine cabinet, but on the dinner table.
Researchers followed 104 adults aged between 65 and 75, assigning them to one of four diets for four weeks: an omnivorous high-fat diet (OHF), an omnivorous high-carbohydrate diet (OHC), a semi-vegetarian high-fat diet (VHF), or a semi-vegetarian high-carbohydrate diet (VHC).
Participants received prepared menu plans, all of which were based largely on minimally processed foods. Carbohydrates came from whole foods including wholegrains, legumes, fruit and vegetables. Although these were not designed as weight-loss diets, most participants did shed some weight.
After four weeks, the omnivorous high-fat group showed no change in biological age. However, the other three groups recorded reductions, measured through clinical indicators such as blood pressure and 20 biomarkers including cholesterol, insulin and C-reactive protein, a marker associated with inflammation.
The strongest effect was seen among those following the omnivorous high-carbohydrate diet, in which 14 per cent of calories came from protein, 28 to 29 per cent from fat and 53 per cent from complex carbohydrates. On average, participants appeared to finish the trial around three and a half years “younger” than at the beginning when compared with the OHF group. The semi-vegetarian diets produced an average reduction of about three years.
For both omnivorous diets, half of the protein came from animal products and half from plant sources. In the semi-vegetarian plans, 70 per cent of protein was plant-based.
An Australian study suggests that the closest thing to an elixir of youth may be found not in a laboratory, but on our dinner plates
“Dairy was included in all four diets,” said Dr Caitlin Andrews, a scientist at the University of Sydney’s School of Life and Environmental Sciences, who led the research.
“Muesli with yoghurt was a standard breakfast across the groups. The semi-vegetarian diet involved replacing red meat and poultry with legumes, soy, nuts and seeds, rather than eliminating animal foods altogether.” For example, participants were served tikka masala made with either chicken or tofu, while casseroles contained either lamb or beans.
Dr Andrews said the researchers designed the diets to reflect real-life eating habits. “Discussions about diet and ageing are often presented as either-or choices: plant versus animal protein, or carbohydrates versus fat.
“In reality, people consume these foods together. The trial therefore allowed us to examine protein sources alongside the balance between fat and carbohydrates, and to assess whether those factors interact to produce a beneficial effect.”
Participants lost an average of 4lb during the study, while 94 per cent recorded at least some weight loss.
“Weight loss occurred in every group, including the higher-fat omnivorous group, which showed no meaningful change in biological age,” Dr Andrews told Good Health. “That means weight loss alone cannot explain the differences between the diets.”
The researchers are still unsure why the lower-fat, higher-carbohydrate diet produced the greatest improvement, but they were surprised by how quickly the changes appeared.
“Four weeks is a short period, and I don’t think we necessarily expected to see a shift within that time,” Dr Andrews said. “However, some individual biomarkers, including C-reactive protein, are known to respond to dietary changes relatively quickly.”
One possible explanation is that the diets moved participants away from a typical Western eating pattern and towards more fibre-rich whole foods.
Dr Thomas Holland, a physician-scientist at Rush University in Chicago who studies how lifestyle changes affect chronic diseases associated with ageing, said the University of Sydney findings were consistent with earlier research.
A large-scale study published in Nature Medicine last year, for instance, followed more than 100,000 people for as long as 30 years. It found that those who lived long and healthy lives tended to consume more fruit, vegetables, wholegrains, unsaturated fats, nuts, legumes and low-fat dairy products.
Those who reported higher intakes of salt, trans fats (formed when liquid fats are made solid, such as in some margarines), sugary beverages and red or processed meats (or both) were less likely to reach 70.
Dr Holland told Good Health: ‘This makes complete sense to me because the diets that improved had several things in common, including lower saturated and trans fats and higher fibre and fruit and vegetables.’
He adds that fibre, for instance, can help steady blood sugar levels, and improve the gut microbiome. Fruit and vegetables also provide a wide range of vitamins, minerals and compounds that can reduce inflammation and oxidative stress – where damaging molecules known as free radicals damage cells. Lowering saturated fat can improve LDL cholesterol and vascular health.
‘These findings also fit well with what we see in the MIND, Mediterranean, and DASH diets, which emphasise many of these same foods while limiting high-fat dairy, butter, fried foods, sweets, and red or processed meats.
‘So I think the bigger takeaway is not one particular food or nutrient – but a high-fibre, minimally processed, nutrient-dense dietary pattern.’
Many studies have shown that healthy eating goes hand in hand with slower biological ageing – including a new study published in Nature Communications.
Researchers in Germany looked at ten different diets, including the Mediterranean diet and the Nordic diet (which focuses on plenty of root vegetables, wholegrains and seafood). Blood samples were checked for markers of DNA methylation, a type of change affecting which genes are turned on or off, that can be used to measure biological age.
Across the board, the diets which were judged to be healthy because they contained plenty of fresh fruit and vegetables and healthy oils – with low amounts of processed food and saturated fats – were associated with slower biological ageing.
Meanwhile, eating too much processed food can speed up the ageing process, in particular driving a process called cellular senescence, when ageing cells become ‘zombies’ and stop dividing but release inflammatory signals.
As Dr Holland explains: ‘Diets high in added sugars, refined carbohydrates, saturated fats, and low in fibre can contribute to metabolic dysfunction [such as type 2 diabetes and obesity] and drive oxidative stress.’
‘Senescent cells can release inflammatory signals that affect surrounding tissue, contributing to chronic inflammation and preventing organs and skin healing and regenerating.’
More studies are needed to show long-term benefits of dietary changes, however.
The University of Sydney study is not yet conclusive about whether the benefits are temporary or permanent.
Dr Andrews said: ‘Our findings reinforce the idea that healthier overall dietary patterns may support healthier ageing over time – and that small, realistic and sustainable improvements to overall diet quality may still have meaningful effects on health as we get older.’
Time to eat more strawberries?
Fisetin, a compound in strawberries, can destroy damaged or ageing cells, which accumulate in tissue as we get older, causing inflammation and damage
Fisetin, a compound in strawberries, can destroy damaged or ageing cells, which accumulate in tissue as we get older causing inflammation and damage, according to a 2024 study in the journal Mechanisms of Ageing and Development.
Strawberries also contain pelargonidin, a compound thought to help reduce the rate of cognitive decline and risk of developing Alzheimer’s dementia.
But Dr Thomas Holland, a US expert on lifestyle and ageing, says it’s not as simple as eating more strawberries.
‘There are several foods that can be thought of as “super” foods, but, from a general perspective, ageing is too complex for one food to be the “magic pill”.
‘It’s the diversity of foods that have a more impactful influence over healthy ageing.’
