Biological age: what we can really measure today and what is still marketing

We are used to thinking of age as a number on an identity document. However, two 65-year-olds can look and feel completely different: one may travel, exercise and maintain a high degree of independence, while the other may already be facing mobility limitations and several chronic diseases.

That is why the concept of biological age has emerged in science: an attempt to estimate not how many years we have lived, but to what extent our body shows characteristics associated with aging.

It sounds convincing. But an important question arises: is it possible to reliably measure the biological age of a specific person today?

The short answer is: partially. Science can measure certain signs of aging quite well and build statistical risk models. However, there is still no single test capable of stating with certainty: “Your body is 54 years old, even though chronologically you are 61.”

What is biological age?

Biological age is not a single indicator that can be observed under a microscope or determined by a single blood test.

It is rather a guiding model that tries to integrate different changes related to aging: cardiovascular status, inflammation, muscle function, cognitive abilities, DNA modifications, proteins and metabolism.

That is why different assessment systems can give different results for the same person.

An epigenetic test may estimate an age of 56, another 61, and a model based on clinical parameters 58.

That does not necessarily mean that one of them is wrong. It may simply mean that they are measuring different aspects of the aging process.

Why chronological age is not enough

Chronological age remains a very important predictor of many diseases. But it does not reflect the large individual differences.

Over the years, the following can change:

• muscle strength and walking speed;
• blood pressure and vascular function;
• glucose and lipid metabolism;
• the level of chronic inflammation;
• cognitive functions;
• the immune system;
• the epigenetic characteristics of cells.

And all these processes evolve at different rates.

It is precisely this variability that researchers try to describe through so-called biomarkers of aging.

What science can measure today

In recent years, international groups of experts have tried to identify which biomarkers are truly useful for assessing aging-related changes.

And it is interesting that not all of them require complex molecular technologies.

Among the indicators considered relevant are muscle mass, muscle strength, grip strength, gait speed, balance, cognitive status, blood pressure, frailty indices, certain inflammatory markers and epigenetic clocks.

This is an important trend in modern longevity science:

to understand how a person ages, it can sometimes be more useful to observe how they move and function than to obtain a single figure from a sophisticated laboratory test.

1. Functional age: an often underestimated indicator

The ability to get up from a chair, walk safely, maintain balance and preserve muscle strength is directly related to independence in advanced age.

That is why relatively simple tests such as:

gait speed, grip strength, the Timed Up and Go test and balance assessment

are now considered important indicators of the body’s functional status.

Their advantage is clear: they do not measure an abstract molecular characteristic, but capabilities directly related to quality of life.

A person may have good lab results and yet be losing muscle strength and mobility. From a clinical point of view, this is highly relevant.

2. Conventional blood tests also provide a lot of information

To assess health during aging, it is not always necessary to start with an expensive genetic test.

Glucose, the lipid profile, certain inflammatory markers, blood pressure and other routine parameters already provide important information about cardiovascular and metabolic risk.

In aging research, markers such as hs-CRP, IL-6, GDF-15 and IGF-1 are also studied.

However, none of them on its own indicates “the age of the body.” They are pieces of a much broader whole.

3. Epigenetic clocks: one of the most interesting technologies

One of the tools that has received the most attention is the so-called epigenetic clocks.

They analyze DNA methylation, that is, chemical modifications that regulate gene activity and that change in a relatively predictable way with age.

The algorithms examine hundreds or thousands of regions of the genome and, from those data, calculate an estimate related to age.

At the population and research level, these models can be very powerful tools. Some are associated with disease risk, mortality or the pace of aging.

But there is an important nuance.

Why epigenetic age should not yet be considered a medical diagnosis

The result can vary depending on:

• how the sample is obtained and processed;
• the laboratory and the platform used;
• the cellular composition of the blood;
• the algorithm used;
• the tissue analyzed;
• the conditions under which the measurement is made.

In addition, different epigenetic clocks were developed with different goals. Some mainly try to predict chronological age, others the risk of disease or mortality, and others aim to estimate the pace of aging.

That is why a figure such as “your biological age is 52” can convey greater precision than it really has.

In the scientific context, these tools are promising, but they are not yet equivalent to a standard clinical diagnostic test for a specific person.

And what about blood proteins?

Another field that is advancing rapidly is that of so-called proteomic aging clocks.

Instead of analyzing DNA changes, they study hundreds or thousands of proteins present in plasma.

Since proteins participate directly in processes such as inflammation, immunity, metabolism and organ function, these models could help identify which systems of the body show greater age-associated changes.

Proteomic clocks are considered one of the most promising areas of current aging research, although their clinical application still requires much broader validation.

Can different organs have different “ages”?

This is one of the most interesting ideas in modern aging research.

A person may maintain very good cardiovascular function and, at the same time, show more pronounced aging of the musculoskeletal system.

In another person, exactly the opposite may occur.

That is why research is beginning to move away from the idea of a single universal biological age and to explore aging profiles specific to different organs and systems.

For example, markers related to the aging of the brain, heart, liver, immune system and other organs are being studied.

In the future, instead of hearing:

“Your body is 58 years old”

we could receive much more useful information, such as:

“Your cardiovascular system shows a certain risk profile, your muscle function another, and your cognitive indicators yet another.”

From a clinical point of view, this type of information could be much more valuable.

Where marketing begins

The problem is not so much the technology as the way the results are interpreted and presented.

It is wise to be cautious about claims such as:

“Discover your true age with one-year precision.”

There is currently not enough scientific basis to claim that degree of precision.

A phrase like this also deserves caution:

“We have shown that after our program you are five years younger.”

If that result is based solely on an epigenetic test, it does not yet show that the body has truly rejuvenated.

Short-term changes in certain biomarkers can reflect normal physiological fluctuations and not necessarily a deep modification of the aging process.

“Five years less of biological age”: what does it really mean?

This is probably one of the most important questions.

If, after an intervention, an algorithm shows a reduction in biological age, we should ask ourselves:

• has the risk of disease decreased?
• has physical function improved?
• has the risk of disability decreased?
• has cognitive function improved?
• has the prognosis for healthy life years changed?

If we cannot answer these questions, the reduction of a number in an app may have limited practical value.

That is why part of current research is trying to develop measures that have a clearer relationship with real medical risks and with health-relevant outcomes.

Can we know today whether a person is aging faster or more slowly?

At the research level, yes, with certain limitations.

As an exact individual diagnosis, it remains much more complicated.

The most reasonable approach at present is not to look for a single perfect test, but to combine different levels of information:

clinical status + physical function + lifestyle + laboratory parameters + molecular biomarkers when necessary.

Multidimensional models are precisely one of the most promising lines of modern aging research.

What matters more than the biological age number

For an older person, something other than knowing whether an algorithm estimates 62 or 67 years is probably more important.

The truly relevant questions are:

• Is muscle strength maintained?
• Can they walk several kilometers comfortably?
• Do they retain good balance?
• Is blood pressure well controlled?
• Are there significant metabolic disorders?
• Are memory and other cognitive functions maintained?
• Is there an active social life?
• Can the person remain independent?

These factors come much closer to what we understand in real life by healthy aging.

So, does biological age really exist?

As a scientific concept, yes.

As a single number that we can measure with absolute precision in anyone today, not yet.

Science is getting better and better at measuring different components of aging. Epigenetics, proteomics, clinical parameters, cognitive tests and functional assessments are building an increasingly detailed picture.

But the most rigorous approach is not to look for a magic number.

What matters is not only knowing how “young” the body appears according to an algorithm, but understanding which systems are working well, where the risks appear and what we can do to preserve health, mobility and independence over the coming years.

And that is probably where the true practical value of the science of biological age lies today.