Quick version
Oxidative stress is a condition that occurs when the body has more free radicals than it can neutralize with antioxidants. The phenomenon is a natural part of metabolism but can increase in cases such as smoking, obesity, stress and long-term illness. In such cases, the load can contribute to cell damage and ill health over time.
What is oxidative stress?
Oxidative stress occurs when the amount of reactive oxygen species, often called ROS, exceeds the body's ability to neutralize them with its antioxidant systems. Reactive oxygen species are formed all the time in the body, especially when cells produce energy in the mitochondria, but also as part of the immune system. ROS are needed in moderate amounts for normal cell signaling, but in excess they can damage fat, proteins and DNA.
When does oxidative stress occur in the body?
The condition can occur both acutely and slowly over time. A hard workout, an infection or a short-term inflammation can cause a temporary increase in ROS. The balance is usually restored quickly in an otherwise healthy person, and the short-term increase can even help the body adapt and become more resilient.
It is when the stress becomes prolonged or repeated so often that the repair systems cannot keep up that problems arise. Examples of what this may be about are:
- long-term smoking
- poor sleep
- chronic inflammation
- high blood sugar levels
- obesity
- air pollution or high alcohol consumption
The risk of cell damage is increased and also the risk that oxidative stress becomes part of the development of the disease instead of a temporary biological reaction.
Many wonder whether psychological stress itself causes oxidative stress. The answer is that psychological stress is not as easy to measure as, for example, exposure to smoke or hyperglycemia, but long-term stress often interacts with lack of sleep, poorer lifestyle habits and low-grade inflammation.
Who is most often affected by oxidative stress?
All people have oxidative processes in their bodies, so in that sense it can be said that everyone is "affected". However, there are certain groups who are at greater risk of having a level of oxidative stress that is linked to ill health. These include people who smoke, live with obesity, type 2 diabetes, long-term inflammatory disease, cardiovascular disease or high exposure to air pollution.
In diabetes, high blood sugar levels can contribute to increased formation of reactive oxygen species and impaired cell function. Oxidative stress is therefore a contributing mechanism in the development of insulin resistance and several diabetes-related sequelae. This does not mean that oxidative stress alone causes diabetes, but that it is one of several mechanisms that can contribute to vascular damage, nerve damage and metabolic disorders.
In obesity (severely overweight people), a combination of low-grade inflammation, mitochondrial dysfunction and increased ROS production is also seen. This can increase insulin resistance and affect the liver, blood vessels and adipose tissue.
Smokers and other people exposed to high levels of air pollution are another clear risk group. Inhaled particles and toxins can drive inflammation and oxidative stress in the respiratory tract, but the effect does not stop in the lungs. Small particles can affect the entire body and are linked to an increased risk of stroke, ischemic heart disease, COPD and lung cancer, among other things.
Age also plays a role, as the cells' repair capacity decreases over time, while cumulative exposure to inflammation, metabolic stress and environmental factors increases. This is an important reason why oxidative stress is often discussed in connection with aging and chronic diseases, even though age itself is not a disease.
What symptoms can you notice?
Oxidative stress rarely causes specific symptoms and therefore cannot be identified with certainty just based on how you feel. It is most often noticed indirectly through non-specific symptoms such as:
- Fatigue
- Low energy
- Slow recovery
- The feeling that the body is not functioning as usual
However, these symptoms can also have many other causes, such as iron deficiency, sleep disorders, thyroid disease, diabetes, infection or stress-related illness. Therefore, it is more important to investigate risk factors and underlying diseases than to see oxidative stress as its own diagnosis.
For example, in the case of abdominal obesity, elevated blood sugar, high blood lipids or smoking, oxidative stress can contribute to the body's burden.
Is it possible to test for oxidative stress?
In research, biomarkers such as F2-isoprostanes, 8-OHdG and products of lipid peroxidation or DNA damage are used. However, these are rarely used in routine healthcare because they are difficult to standardize and not sufficiently clinically validated.
It is often more relevant to examine risk factors through, for example, blood sugar, HbA1c, blood fats, liver samples and other markers of metabolic health. Depending on symptoms, blood status, iron status, vitamin values and thyroid tests may also be relevant. What can be done to reduce oxidative stress? Focus on reducing the body's biological load: If you smoke, quit. Treat high blood sugar, insulin resistance, obesity and type 2 diabetes. Exercise regularly and sustainably. Hard training can temporarily increase oxidative markers, but regular training strengthens the body's defenses over time.
Oxidative stress is rarely an isolated problem, but often reflects how the body reacts to stress. Therefore, good metabolism, sleep, physical activity and a healthy everyday environment are more important than focusing solely on antioxidants.
