A reanalysis of a randomized trial found that changing diet for four weeks can lower biomarker-based estimates of biological age in older adults. Researchers provided all meals to participants aged 65–75 (BMI 20–35) and compared four diet patterns that varied by protein source and macronutrient balance. The omnivorous high-carbohydrate group showed a statistically significant reduction in estimated biological age; two semi-vegetarian patterns showed similar but less consistent declines. Authors caution that longer trials are needed to determine whether these short-term changes lead to lasting health benefits.
Four-Week Diet Change Rapidly Lowers Biological Age Markers in Older Adults, Study Finds
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New analysis suggests a short-term dietary change can reduce biological signs of aging in older adults. Researchers reexamined data from a randomized clinical trial and found that switching macronutrients and protein sources for just four weeks produced measurable improvements in biomarker-based estimates of biological age.
Study Design and Diets
The reanalysis used data from the Nutrition for Healthy Living (NHL) randomized trial. Participants were adults aged 65–75 with a body mass index (BMI) of 20–35. For four weeks the study supplied all meals and randomly assigned participants to one of four diets, each providing 14% of energy from protein.
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Two diet patterns were omnivorous (protein split evenly between animal and plant sources) and two were semi-vegetarian (70% of protein from plant sources). Within each pattern, participants followed either a high-fat, low-carbohydrate or a low-fat, high-carbohydrate plan, producing four groups: omnivorous high-fat (OHF), omnivorous high-carbohydrate (OHC), semi-vegetarian high-fat (VHF), and semi-vegetarian high-carbohydrate (VHC).
How Biological Age Was Estimated
Researchers calculated biological age using the Klemera-Doubal Method, combining 20 biomarkers that reflect physiological function. These included blood pressure and blood concentrations of insulin, cholesterol, and C-reactive protein (CRP), among others. Biological age estimates aim to capture an individual’s physiological state and potential health risks more directly than chronological age.
Dietary changes in older age may still be an effective way to rapidly improve biomarkers associated with aging. (Piersey/Flickr/CC BY 4.0)
Key Findings
Of the four diets, the OHF pattern most closely resembled participants' reported habitual diets at baseline and produced no significant change in biological age. By contrast, the omnivorous high-carbohydrate (OHC) group experienced a statistically significant reduction in estimated biological age. The two semi-vegetarian groups (VHF and VHC) showed similar reductions in biological age estimates, but these declines were not always statistically significant.
"It's too soon to say definitively that specific changes to diet will extend your life," said Caitlin Andrews, a nutrition scientist at the University of Sydney and the study's first author. "But this research offers an early indication of the potential benefits of dietary changes later in life."
Senior author commentary emphasized caution: longer and larger trials are needed to determine whether short-term improvements in biomarkers translate into durable protection against age-related diseases or longer lifespan.
What This Means
These preliminary results suggest that modifying diet—even later in life—can influence physiological markers associated with aging within a short period. However, the clinical significance and persistence of these changes remain uncertain. The analysis was published in the journal Aging Cell.
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