Just four weeks of switching to diets rich in whole-food complex carbohydrates and plant-based foods shifted aging-related biomarker profiles in older adults. However, scientists say the changes may reflect rapid physiological adaptation rather than true age reversal.
Study: Short-Term Dietary Intervention Alters Physiological Profiles Relevant to Ageing. Image credit: Wuttichok Panichiwarapun/Shutterstock.com
Short-term dietary interventions can alter age-related physiological changes in older adults, as reported by a new study published in Aging Cell.
How diet may shape physiological aging
Aging is a multifactorial biological process characterized by complex molecular, cellular, and physiological changes. This inevitable biological process is typically associated with health deterioration and increased risk of diseases and death.
Chronological age, the exact time elapsed since birth, is considered the actual age of a person that increases uniformly with time. Biological age, on the other hand, is considered the functional age that accurately indicates a person’s health and mortality risk, regardless of his or her chronological age.
Unlike chronological age, biological age varies widely across individuals and is influenced by several modifiable factors, such as diet and physical activity. Diet is one of the key modifiable determinants that can potentially modulate age-associated biomarker profiles. In this context, evidence indicates that animal- and plant-based foods differentially influence biomarkers associated with key aging markers, including inflammation and oxidative stress.
Studies investigating the health benefits of different dietary patterns have shown that macronutrients, such as protein, carbohydrates, and fats, can differentially modulate biomarkers and physiological profiles associated with aging, highlighting the need for more in-depth research to explore beneficial changes in age-related biomarkers across dietary patterns.
Researchers at the University of Sydney, Australia, recently investigated the effect of short-term dietary interventions on age-related physiological status in older adults by using the Klemera-Doubal Method (KDM). This method estimates age-related physiological status by integrating a set of blood and clinical biomarkers known to vary systematically with chronological age at the population level.
The difference between chronological age and KDM-generated age, commonly used as a proxy for biological age, represents the extent to which a person's biomarker profile aligns with or diverges from age-typical expectations. A smaller value indicates closer alignment with typical physiological profiles for a person’s age. Positive values suggest a physiologically older-than-expected profile, whereas negative values indicate a healthier or more resilient physiological state.
Four-week trial compared carbohydrate and fat ratios
The researchers analyzed data from the Nutrition for Healthy Living study (NHL) using the KDM algorithm. NHL was a randomized dietary trial involving 104 older adults aged 65–75 years.
The participants were randomly assigned to one of the four dietary interventions: animal-based high-fat, animal-based high-carbohydrate, semi-vegetarian high-fat, and semi-vegetarian high-carbohydrate.
The difference between chronological age and KDM-generated age (used here as a proxy for biological age or age-related physiological status) was measured at baseline (before the start of the intervention) and after the 4-week intervention period.
Plant-forward diets shifted age-related biomarker profiles
The study analysis revealed that the 4-week dietary interventions measurably influenced KDM-derived physiological age profiles in older adults.
Specifically, the study found no significant changes in KDM-derived age profiles among participants consuming an animal-based high-fat diet. In contrast, participants consuming an animal-based high-carbohydrate diet, a semi-vegetarian high-fat diet, or a semi-vegetarian high-carbohydrate diet showed reductions in KDM-derived age profiles compared to the animal-based high-fat group.
The reduction was statistically significant among participants consuming the animal-based high-carbohydrate diet. Participants on the semi-vegetarian high-fat diet also showed statistically significant reductions in one KDM measure, while those on the semi-vegetarian high-carbohydrate diet showed reductions that were not statistically significant.
Rapid diet-driven biomarker responsiveness
The study highlights the potential impact of short-term dietary interventions on KDM-derived age, a widely used proxy for biological age in large epidemiological cohorts. The findings also support the usefulness of KDM-derived age for assessing age-related shifts in physiological status in older adults.
The researchers, however, advised careful consideration of these findings as evidence of biological age reversal or delay, because the observed shifts may reflect acute physiological responsiveness to dietary components rather than altered aging trajectories.
Age-related biomarkers considered in KDM are influenced by metabolic, cardiovascular, and inflammatory states. Since these states are highly sensitive to short-term dietary changes, it remains possible that the observed changes are acute physiological responses rather than a reversal of age-related dysfunction. The researchers emphasized that the study was not designed to determine whether the observed changes represent true slowing of biological aging or merely short-term adaptive physiological responses to dietary intake.
Future research with longer intervention and follow-up periods is therefore needed to assess whether the observed reduction in KDM-derived age measures in response to dietary changes persists after the intervention period or predicts long-term outcomes.
The dietary interventions tested in this study have been explored by several other studies. The findings of these studies indicate that these diets, particularly those rich in whole-food, complex carbohydrates, are associated with increased lifespan, improved metabolic health, and reduced risk of chronic diseases across species. Carbohydrates used in these diets are derived from whole, minimally processed sources, and therefore should not be confused with refined or simple carbohydrates, which may induce different metabolic effects.
Previous studies analyzing data from the NHL trial have shown that these diets substantially differ from participants’ habitual diets, except for the animal-based, high-fat diet, which most closely resembled participants' habitual diet and exhibited no change in KDM-derived age measures after the intervention period.
Participants’ habitual diets closely resembled those of typical Australians, which are rich in refined sugar, saturated fat, and processed foods. The absence of beneficial changes following this dietary intervention was consistent with broader evidence linking Western dietary patterns to poorer metabolic health.
The NHL study population considered in this study represents a relatively healthy subpopulation with greater physiological resilience relative to age norms. At baseline, participants on average already exhibited negative KDM-derived age values, indicating comparatively resilient physiological profiles. This may restrict the generalizability of the findings to other populations with suboptimal health status. Future research with more diverse cohorts is needed for further validation.
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