Imagine a world where a single drop of blood or saliva could reveal not only your biological age, but also provide a window into how well you might age in the years ahead.

This is no longer a futuristic fantasy, but a reality emerging from the latest research into intrinsic capacity and the science of ageing. The concept of intrinsic capacity, as defined by the World Health Organisation, captures the sum of physical and mental abilities available to an individual—ranging from the ability to walk and see, to memory and cognitive function.

Traditionally, measuring this holistic view of health has required expensive equipment and time-intensive assessments. That has just changed.

A recent study published in the respected journal Nature Aging has introduced a transformative method. By analysing DNA methylation patterns—a type of chemical tag that influences gene activity—from just a single drop of blood or saliva, scientists have devised what they call an “IC clock.”

This tool can predict not only how well you are ageing, but also your risk for mortality and functional decline. This leap in technology signals an era where tracking your biological resilience could become as routine as checking your cholesterol.

So, why does intrinsic capacity matter? Healthy ageing is not simply about adding years to life, but adding life to years. As people grow older, physical and mental functions often diminish. Yet, the rate at which this happens varies dramatically between individuals. Some remain sharp and spry well into their nineties, while others face significant decline decades earlier.

Intrinsic capacity provides a framework for understanding this difference. It encompasses cognition, locomotion, sensory perception, psychological well-being and vitality. In essence, it’s a measure of how robustly your body and mind are holding up against the tides of time.

Until now, evaluating these domains has required batteries of physical exams, cognitive assessments and laboratory tests—barriers that made wide-scale assessment impractical. The new blood or saliva test changes that equation completely. Imagine visiting your GP for a check-up and leaving with a precise report on not just how old you are on paper, but how well your cells and organs are performing compared to your peers. This could redefine preventive medicine for older adults.

The science underpinning this innovation lies in epigenetics—the study of chemical modifications that switch genes on or off without altering the underlying DNA sequence. DNA methylation is a key part of this process.

Over time, environmental factors, lifestyle choices and disease can leave their mark on these methylation patterns. By examining them, researchers have constructed an “epigenetic clock” for intrinsic capacity, dubbed DNAm IC. In their study involving more than a thousand participants aged from 20 to 102 years, the team demonstrated that the DNAm IC score powerfully predicts all-cause mortality.

Individuals with higher DNAm IC scores enjoyed better lung function, faster walking speed, denser bones and were more likely to report feeling healthy. Most strikingly, those with high DNAm IC lived on average 5.5 years longer than those with low scores.

The implication is clear: maintaining intrinsic capacity is not just about feeling good now—it’s about extending life and health deep into old age.

What factors influence this new measure of biological ageing? Diet looms large. The research highlighted that people with high consumption of oily fish—rich in long-chain omega-3 fatty acids—tended to score higher on DNAm IC.

Omega-3s are renowned for their anti-inflammatory properties and support for brain health. They also play a role in maintaining robust immune function and protecting cells from damage as we age.

Conversely, keeping sugar intake within recommended limits was also associated with higher scores. Excessive sugar is known to drive inflammation and metabolic dysfunction, both enemies of healthy ageing.

Experts in the field point out that the DNAm IC test does more than traditional epigenetic clocks. While previous tests could estimate biological age by examining methylation patterns across the genome, the new test goes further by focusing on domains most relevant to functional ageing—such as immunity and physical capacity. This means it’s better equipped to guide personalised interventions aimed at maintaining independence and vitality in older adults.

However, experts also urge caution. While the DNAm IC test is a powerful addition to the toolkit for assessing ageing, it should be used alongside other established markers like PhenoAge and GrimAge, as well as functional tests that directly measure strength, memory and mobility. Further validation in diverse populations will be critical before widespread adoption in clinics.

Beyond diet, what else can individuals do to support their intrinsic capacity? Regular physical activity remains a cornerstone. Aerobic exercise, strength training and balance work all contribute to preserving muscle mass, bone density and neurological health. Cognitive engagement—through learning new skills or participating in social activities—has been repeatedly linked to slower cognitive decline. Managing chronic conditions such as hypertension or diabetes is equally important for protecting long-term function.

Stress management is another pillar. Chronic stress accelerates inflammatory processes that undermine both physical and mental resilience. Mindfulness practices, adequate sleep and maintaining strong social connections all support healthy ageing.

What does this mean for the future? The ability to track intrinsic capacity using a non-invasive test opens up exciting possibilities for preventive medicine. Such a tool enables clinicians to identify individuals at risk of rapid decline before symptoms appear—giving people time to make lifestyle changes or start interventions that could make a tangible difference in how they age.

Moreover, this test could become central in research into new therapies targeting the biology of ageing itself. As longevity medicine moves from theory to practice, having reliable molecular markers will be essential for measuring success.

Experts describe this development as a significant advance because it links molecular biology directly with real-world outcomes like mobility and cognition—not just arbitrary markers in the lab. In other words, it bridges the gap between what happens at the microscopic level in our cells and what we experience in daily life.

While further studies will be necessary—especially among older adults with already low intrinsic capacity—the groundwork has now been laid for using personalised epigenetic markers to tailor interventions in preventive geriatrics and public health.

For now, the message remains simple but powerful: Healthy ageing is not just about genetics or luck—it’s within our control to a surprising degree. Eating a balanced diet rich in fresh fruit, vegetables and healthy fats; staying physically active; keeping mentally engaged; managing stress; and following medical advice for chronic conditions all contribute meaningfully to maintaining intrinsic capacity.

As science continues to unravel the mysteries of ageing, tools like the DNAm IC test will help turn knowledge into action—making it possible not only to live longer but to thrive into advanced age.