Every cell in the body contains DNA. It carries the instructions that help cells grow, repair themselves and do their job.
DNA is very well protected, but it is not completely safe from damage. Everyday metabolism, environmental toxins, radiation and other forms of stress can all affect it.
The body has repair systems that find and correct many of these changes.
But these systems are not perfect.
As we grow older, DNA damage can build up faster than the body can repair it. Scientists call this genomic instability.
This does not mean that every change in DNA will cause disease. Many changes are repaired, and some have little effect.
The problem begins when damage becomes more common, repair becomes less effective and altered cells remain in the body.
Over time, this may make it harder for cells to work properly. In some cases, it may also increase the risk that a cell begins to grow in an uncontrolled way.
This is one reason researchers study DNA damage so closely: some changes that are not repaired may contribute to the development of cancer. DNA damage can also affect other parts of biological ageing.
It may change how genes are used, place extra pressure on the systems that produce energy or cause a damaged cell to stop dividing.
A problem in one area can therefore place more pressure on several others.
The body has different ways to protect itself.
It can repair damaged DNA, pause cell division or remove a cell that has become too damaged to remain safe.
These responses are essential, but they can also become less effective with age.
Genomic instability cannot be measured with one simple DNA test.
A single result cannot show all the damage and repair taking place across the brain, heart, muscles, liver and other tissues.
The concept is useful because it helps explain why long-term exposure and cellular maintenance matter throughout life.
Some DNA damage is unavoidable. Normal activity inside a cell creates stress.
But we can reduce unnecessary damage by avoiding smoking and limiting contact with harmful substances and unnecessary radiation.
Regular physical activity, adequate sleep, balanced nutrition and preventive medical care also support the wider conditions that cells need to maintain and repair themselves.
We cannot keep DNA completely unchanged throughout life.
The goal is to reduce avoidable damage and help the body recognise, repair and control it for as long as possible.
