Researchers at the University of Sydney say certain diet changes may help slow the aging process in older adults in as little as four weeks.
The study focused on “biological age,” which measures how old the body appears based on health markers instead of actual years lived. Researchers found that participants who reduced fat intake or ate more plant-based foods showed improvements in biomarkers tied to aging after just one month.
The findings were published in the journal Aging Cell.
The study included 104 adults between the ages of 65 and 75. Participants were randomly assigned to one of four diets. Two of the diets were omnivorous and included both animal and plant protein. The other two were semi-vegetarian, with 70% of protein coming from plant sources.
Researchers also divided the diets by fat and carbohydrate content. Some participants followed high-fat, low-carbohydrate diets, while others followed low-fat, high-carbohydrate diets.
All four diets contained the same amount of protein, with 14% of total energy intake coming from protein sources.
Scientists measured 20 biomarkers connected to aging and overall health. These included cholesterol levels, insulin levels, and C-reactive protein levels. Researchers used those markers to calculate each participant’s biological age.
According to the University of Sydney, biological age can provide a better picture of health and longevity than chronological age alone.
“While chronological age increases uniformly, biological aging varies between individuals, reflecting differences in health status and the body’s resilience,” the university said in a report on the study.
After four weeks, participants in three of the four diet groups showed reductions in biological age scores. The only group that did not show meaningful improvement was the omnivorous high-fat group. Researchers noted that this group’s diet was closest to what many participants were already eating before the study began.
The strongest evidence for reduced biological age came from the omnivorous high-carbohydrate group. That diet included 14% protein, roughly 28% to 29% fat, and 53% carbohydrates.
The researchers said diets rich in complex carbohydrates and plant-based foods appeared to produce the most noticeable improvements.
Dr. Caitlin Andrews, who led the study at the University of Sydney’s School of Life and Environmental Sciences, said the findings are still early and should be interpreted carefully.
“It’s too soon to say definitively that specific changes to diet will extend your life,” Andrews said. “But this research offers an early indication of the potential benefits of dietary changes later in life.”
Associate Professor Alistair Senior, who supervised the research, said longer-term studies are still needed.
“Longer-term dietary changes are needed to assess whether dietary changes alter the risk of age-related diseases,” Senior said.
Researchers also said future studies should examine whether these changes last over time and whether they can predict better long-term health outcomes.
The participants in the study all had body mass index scores between 20 and 35. Researchers said they were non-smokers, non-vegetarians, and free of major medical conditions such as cancer, kidney disease, liver disease, and Type 2 diabetes.
Researchers said future studies will examine whether the improvements seen in the study can last long term and reduce the risk of age-related diseases later in life.