Study Finds Diet Changes May Reduce Biological Age in Older Adults

We will all grow older eventually, if we are fortunate, although we do not necessarily age at an identical pace.

Chronological age increases at the same rate for everyone, whereas biological age may differ according to influences including genetics, the air around us and the food we consume.

Diet and biological age

Diet is among the adjustable factors associated with the ability to withstand the demands of ageing. It may influence inflammation, metabolism, cardiovascular health and other bodily systems that commonly change over time.

Such effects could mean that, at a cellular level, we appear younger than our actual age.

A new study indicates that eating nutritious food may deliver this advantage even when a person's chronological age is already comparatively advanced. Although beginning earlier may be preferable, the findings indicate that changing the diet later in life can still be an effective means of quickly improving biomarkers associated with ageing.

"It's too soon to say definitively that specific changes to diet will extend your life," cautions first author Caitlin Andrews, a nutrition scientist at the University of Sydney in Australia.

"But this research offers an early indication of the potential benefits of dietary changes later in life."

The Nutrition for Healthy Living study diets

Andrews and her colleagues drew on information from the Nutrition for Healthy Living (NHL) study, a randomised clinical trial examining how dietary protein sources and individual macronutrients affect older adults' health.

For the NHL study, researchers enrolled adults aged 65 to 75 with a body mass index of 20 to 35. They then randomly allocated participants to one of four diets for four weeks, with every meal provided by the study team.

Each eating plan supplied 14 percent of its energy from protein. Two diets were omnivorous, with protein divided equally between animal and plant sources, while the other two were semi-vegetarian, with plants providing 70 percent of protein.

Participants in both the omnivorous and semi-vegetarian categories were also assigned a complementary diet based on either high-fat, low-carbohydrate foods or low-fat, high-carbohydrate foods.

This created four dietary patterns overall: omnivorous high-fat (OHF), omnivorous high-carbohydrate (OHC), semi-vegetarian high-fat (VHF), and semi-vegetarian high-carbohydrate (VHC).

Biomarkers linked to ageing

Scientists can calculate biological age from biomarker profiles – measurements of physiological function that may offer greater insight into health and possible longevity than simply counting the years since birth.

The University of Sydney team examined NHL data to establish whether dietary alterations in older adults could affect biological age. They calculated this measure with the Klemera-Doubal Method.

The study used information from 20 biomarkers, including blood pressure and blood concentrations of insulin, cholesterol and C-reactive protein, to estimate participants' biological ages.

Researchers noted that, of the four dietary categories, OHF most closely resembled the usual diets participants said they followed before the trial. This may account for it having the smallest impact on biological age, as it produced no significant shift in the relevant biomarkers.

The remaining three diets, by contrast, appeared to lower participants' biological ages.

The findings showed a significant reduction among people following the OHC diet. The VHF and VHC groups recorded similar decreases, although these did not consistently achieve statistical significance.

Whether these results would result in lasting protection from declining health is still uncertain.

"Longer-term dietary changes are needed to assess whether dietary changes alter the risk of age-related diseases," says Alistair Senior, a nutritional ecologist at the University of Sydney.

These encouraging early results point to the value of additional research.

"Future research should explore whether these findings extend to other cohorts," Andrews says, "and whether the changes recorded are sustained or predictive of long-term outcomes."

The study appeared in Aging Cell.