Finding a way to slow the ageing process has fascinated humanity for centuries and remains a major goal of modern medicine. Yet new research suggests the answer may not depend on costly, cutting-edge treatments. Instead, a carefully structured diet could help lower a person’s biological age.
Remarkably, researchers say measurable improvements may appear in fewer than four weeks.
The findings, from an Australian study published in the journal Aging Cell, have raised the possibility that a practical “fountain of youth” could be found not in a laboratory or medicine cabinet, but in everyday food choices.
Researchers followed 104 adults between the ages of 65 and 75, assigning them to one of four eating plans 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 menus, all based largely on minimally processed ingredients. Carbohydrates came from whole foods, including wholegrains, beans, fruit and vegetables. Although the plans were not specifically designed for weight loss, most participants shed some weight during the trial.
By the study’s conclusion, the omnivorous high-fat group showed no significant shift in biological age. The other three groups, however, recorded reductions. Biological age was assessed through clinical measures such as blood pressure, along with 20 biomarkers including cholesterol, insulin and C-reactive protein, an indicator associated with inflammation.
The strongest results came from the omnivorous high-carbohydrate plan, which supplied 14 per cent of calories from protein, 28 to 29 per cent from fat and 53 per cent from complex carbohydrates. On average, participants following this diet ended the trial with a biological age approximately three and a half years lower than at the beginning, compared with those on the omnivorous high-fat plan. The semi-vegetarian diets produced an average reduction of about three years.
For both omnivorous diets, animal foods provided half of the protein, with the remainder coming from plants. The semi-vegetarian plans contained 70 per cent plant-based protein.
An Australian study suggests that a diet rich in whole foods could offer one of the most promising lifestyle approaches to reducing biological age
“Dairy products were included in all four eating plans,” said Dr Caitlin Andrews, who led the research at the University of Sydney’s School of Life and Environmental Sciences.
Breakfast commonly consisted of muesli and yoghurt. In the semi-vegetarian groups, red meat and poultry were replaced with foods such as beans, soy, nuts and seeds, rather than removing animal products altogether. Meals could include either chicken or tofu tikka masala, for example, or a casserole prepared with lamb or beans.
Dr Andrews said the researchers aimed to create eating plans that reflected real life. “Discussions about diet and ageing are often presented as a choice between two extremes — plant or animal protein, carbohydrates or fat,” she said.
“In practice, people consume combinations of these foods. This trial allowed us to examine protein sources and the balance between fat and carbohydrates at the same time, including whether those factors work together to produce health benefits.”
Participants lost an average of 4lb during the four-week study, while 94 per cent recorded at least some weight loss.
Speaking to Good Health, Dr Andrews said the weight reduction occurred in every group, including the higher-fat omnivorous group, which did not experience a meaningful change in biological age. That suggests weight loss by itself cannot account for the differing results between diets.
Researchers do not yet know precisely why the lower-fat, higher-carbohydrate plan produced the greatest improvement. They were also surprised that changes appeared so quickly.
“Four weeks is a relatively short period, so we did not necessarily expect to see a change within that time,” Dr Andrews said. However, she noted that some biomarkers, including C-reactive protein, can respond to dietary changes fairly rapidly.
A possible explanation is that the meal plans moved participants away from a typical Western diet and toward fibre-rich, minimally processed foods.
Dr Thomas Holland, a physician-scientist at Rush University in Chicago who studies lifestyle changes and age-related chronic disease, said the Australian research was consistent with earlier evidence.
A large study published in Nature Medicine last year followed more than 100,000 people for as long as three decades. It found that those who lived longer and remained healthier tended to eat more fruit, vegetables, wholegrains, unsaturated fats, nuts, legumes and low-fat dairy products.
KEEP READING: The 5 Best Disaster Movies of the 21st Century, Ranked
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.’