By Christopher Job
Oxidative stress is an imbalance between free radicals and antioxidants in the body, which can lead to cellular and tissue damage. Free radicals are molecules with one or more unpaired electrons. Examples include superoxide, hydroxyl radicals, and nitric oxide radicals. External substances—such as cigarette smoke, pesticides, and ozone—can also contribute to the formation of free radicals in the body.
Antioxidants are substances that neutralise or remove free radicals by donating an electron. This neutralising effect helps protect the body against oxidative stress. Examples of antioxidants include vitamins A, C, and E.
Source of oxidative stress
Oxidative stress occurs naturally and plays a role in both the ageing process and the development of various diseases. Studies have shown that long-term oxidative stress contributes to several chronic conditions, such as cancer, diabetes, and heart disease.
Many lifestyle factors can influence oxidative stress. The body’s cells naturally produce free radicals during normal metabolic processes. At the same time, cells also generate antioxidants to counteract them. In general, the body strives to maintain a balance between free radicals and antioxidants. However, certain factors can disrupt this balance and lead to oxidative stress. These include poor diet, unhealthy lifestyle choices, and environmental exposures such as pollution and radiation.
Like free radicals, antioxidants have multiple sources. While the body produces antioxidants such as glutathione, diet also plays a crucial role. Fruits and vegetables provide many essential antioxidants in the form of vitamins and minerals that the body cannot synthesise on its own.
Physical exercise increases free radical formation, which can cause temporary oxidative stress in the muscles. However, these free radicals also play regulatory roles—stimulating tissue growth and prompting the production of endogenous antioxidants. Mild oxidative stress can, in fact, support the immune system and protect the body from infections. Nevertheless, prolonged oxidative stress damages cells, proteins, and DNA. Over time, this contributes to ageing and is implicated in the development of various diseases.
Common complications
Oxidative stress is also linked to chronic inflammation. Infections and injuries activate the body’s immune response, producing free radicals that, in excess, can harm healthy cells and trigger inflammation. Furthermore, oxidative stress can itself initiate inflammatory responses, creating a cycle in which inflammation generates more free radicals and vice versa. This chronic inflammation has been associated with conditions such as diabetes, cardiovascular disease, and arthritis.
The brain is particularly vulnerable to oxidative stress. It consumes approximately 20 per cent of the body’s oxygen to sustain high metabolic activity in brain cells—processes which naturally generate free radicals. These radicals play roles in cell growth, neuroplasticity, and cognitive functioning. However, during oxidative stress, excess free radicals can damage cellular structures in the brain and lead to cell death. This may increase the risk of neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
In fact, oxidative stress has been linked to a wide range of conditions, including cancer, Alzheimer’s disease, Parkinson’s disease, diabetes, cardiovascular diseases (such as hypertension, atherosclerosis, and stroke), inflammatory disorders, chronic fatigue syndrome, asthma, and male infertility.
Risk factors and prevention
Environmental pollution is a significant contributor to long-term oxidative stress. Other risk factors include obesity, diets high in fat, sugar, and processed foods, exposure to radiation, cigarette or tobacco smoking, alcohol consumption, certain medications, and exposure to pesticides or industrial chemicals.
It is important to note that the body requires both free radicals and antioxidants to function optimally. An excess or deficiency of either can lead to health issues.
Lifestyle and dietary changes can help reduce oxidative stress. These include:
Eating a balanced, nutrient-rich diet with plenty of fruits and vegetables
Limiting consumption of processed foods, especially those high in sugar and unhealthy fats
Engaging in regular physical activity
Quitting smoking
Reducing stress
Avoiding or limiting exposure to pollution and harsh chemicals
Maintaining a healthy body weight is also beneficial. Excess fat cells release inflammatory substances that can increase both inflammation and free radical production in the body’s immune cells.
