A new study from researchers at the University of Sydney suggests that relatively small dietary adjustments could help older adults reduce markers linked to biological aging. The findings add to growing international research showing that nutrition may play a major role in healthy aging and long-term cardiovascular health.
Published in the journal Aging Cell, the study found that older adults who followed a low-fat, high-carbohydrate omnivorous diet for four weeks experienced the greatest improvements in several biological age indicators, including cholesterol, insulin and blood pressure levels.
What Is Biological Age?
Unlike chronological age, which simply measures how many years a person has lived, biological age reflects how well the body is functioning internally. Factors such as heart health, metabolism, inflammation and digestion can all influence biological aging.
As a result, two people of the same chronological age may have very different biological profiles depending on their lifestyle and overall health. Canadian health experts have increasingly emphasized preventive approaches — including diet and exercise — as the country’s population continues to age.
University of Sydney Study Examined Four Diet Types
The research was led by Caitlin Andrews from the University of Sydney’s School of Life and Environmental Sciences.
The study involved 104 adults between the ages of 65 and 75. Participants had body mass index (BMI) scores ranging from 20 to 35 and did not have serious medical complications, food allergies, smoking habits or vegetarian diets prior to the study.
Researchers randomly assigned participants to one of four eating plans:
The Four Diet Groups
Omnivorous High-Fat, Low-Carbohydrate Diet
Participants continued eating animal-based foods while consuming higher levels of dietary fat and fewer carbohydrates.
Omnivorous Low-Fat, High-Carbohydrate Diet
This group consumed a diet lower in fat and richer in carbohydrates while still including animal products.
Semi-Vegetarian High-Fat, Low-Carbohydrate Diet
Participants reduced meat intake but followed a higher-fat, lower-carb eating pattern.
Semi-Vegetarian Low-Fat, High-Carbohydrate Diet
This group combined reduced meat consumption with a lower-fat, higher-carbohydrate approach.
Largest Improvement Seen in High-Carb, Low-Fat Group
Researchers evaluated 20 separate biomarkers to estimate participants’ biological age. These markers were analyzed collectively to determine how each diet influenced aging-related health measures.
The most notable improvements were observed among participants following the omnivorous low-fat, high-carbohydrate diet. Their average nutritional balance consisted of roughly 14 per cent protein, 29 per cent fat and 53 per cent carbohydrates.
According to the study, this group experienced the greatest decline in biological age markers over the four-week period.
Meanwhile, participants who adopted semi-vegetarian diets also began showing signs of slower biological aging, though the changes were less pronounced.
By contrast, individuals who maintained a high-fat, low-carbohydrate omnivorous diet showed no significant improvement in biological aging indicators.
What the Findings Could Mean for Older Adults
The researchers say the results highlight the potential impact of dietary balance on healthy aging, particularly for older adults seeking to improve cardiovascular and metabolic health.
While the study was relatively short-term, the findings align with broader evidence supporting diets rich in complex carbohydrates, fibre and plant-based foods. In Canada, similar nutritional guidance is reflected in recommendations from public health agencies that encourage balanced meals emphasizing vegetables, whole grains and reduced saturated fat intake.
The researchers caution that more long-term studies are needed to determine how lasting these biological age improvements may be and whether similar benefits would apply across broader populations.
A Growing Focus on Healthy Aging
As life expectancy continues to rise globally, interest in strategies that support healthier aging has expanded significantly. Researchers are increasingly studying how nutrition, physical activity and lifestyle habits can influence not just lifespan, but overall quality of life later in life.
The latest findings from the University of Sydney add to that growing body of evidence, suggesting that even modest dietary changes may help support healthier biological aging in older adults.
