Oxidative stress - mechanisms, effects and methods of counteracting

Oxidative stress is a state of imbalance between the production of reactive oxygen species (ROS) and the body's ability to neutralize them with antioxidants. Under physiological conditions, ROS perform important regulatory and signaling functions in the body, but their excess leads to damage to biomolecules, which can result in serious health consequences. Contemporary research indicates a key role of oxidative stress in the pathogenesis of many chronic diseases, including atherosclerosis, neurodegenerative diseases, type 2 diabetes, and cancer (Liguori et al., 2018).

2. What is oxidative stress?

Oxidative stress is a disturbance of redox homeostasis that results from excessive production of ROS or impaired functioning of antioxidant systems. ROS are oxygen molecules containing an unpaired electron, which makes them highly reactive and capable of damaging proteins, lipids, and DNA. The most important ROS include superoxide anion (O₂•⁻), hydrogen peroxide (H₂O₂), and hydroxyl radical (•OH) (Sies, 2017).

The body has a number of protective mechanisms that allow it to neutralize excess ROS, but their failure or excessive exposure to prooxidant factors can lead to oxidative stress and cellular damage.

3. Causes of oxidative stress

3.1 External factors

Oxidative stress can be caused by numerous environmental factors that increase ROS production. The most important include:
• Air pollution – exposure to heavy metals (e.g. lead, cadmium) and smog particles may induce the formation of free radicals (Valavanidis et al., 2013).
• UV radiation – intense exposure to ultraviolet radiation leads to the formation of ROS in the skin, which may contribute to photoaging and skin cancer (Wang et al., 2017).
• Tobacco smoking – Tobacco smoke contains over 4,000 chemicals, many of which have pro-oxidant effects, leading to chronic oxidative stress (Pryor & Stone, 1993).

3.2 Internal factors
• Unhealthy lifestyle – inappropriate diet low in antioxidants, lack of physical activity and chronic psychological stress may increase oxidative stress (Furukawa et al., 2017).
• Chronic diseases – diabetes, hypertension and obesity lead to increased production of ROS, which may further exacerbate the course of these diseases (Rani et al., 2016).

4. Symptoms and effects of oxidative stress

Long-term oxidative stress leads to cumulative damage to biomolecules, which increases the risk of chronic diseases.

4.1 Cellular damage
• Proteins – oxidation of proteins causes them to misfold and lose function, which can lead to neurodegeneration (Butterfield & Halliwell, 2019).
• Lipids – lipid peroxidation of cell membranes leads to their destabilization and cell death (Ayala et al., 2014).
• DNA – ROS-induced mutations are associated with carcinogenesis and aging processes (Cooke et al., 2003).

4.2 Diseases related to oxidative stress

Research indicates that oxidative stress plays a key role in the pathogenesis of numerous diseases, such as:
• Atherosclerosis – oxidation of LDL lipoproteins contributes to the formation of atherosclerotic plaque (Stocker & Keaney, 2004).
• Neurodegenerative diseases – excessive production of ROS in the brain is associated with Parkinson's and Alzheimer's disease (Barnham et al., 2004).
• Cancer – chronic oxidative stress promotes mutations and neoplastic transformation (Reuter et al., 2010).

5. Mechanisms of protection against oxidative stress

The body has natural mechanisms to neutralize excess ROS.

5.1 Enzymatic antioxidants
• Superoxide dismutase (SOD) – catalyzes the conversion of superoxide anion to the less reactive hydrogen peroxide.
• Catalase (CAT) – breaks down hydrogen peroxide into water and oxygen.

7:08

Anna Wasilewska

• Glutathione peroxidase (GPx) – reduces hydrogen peroxide and lipid peroxides (Halliwell & Gutteridge, 2015).

5.2 Non-enzymatic antioxidants
• Vitamins C and E – neutralize free radicals, protecting lipids and proteins from oxidation.
• Glutathione – a major intracellular antioxidant that plays a key role in detoxification (Lu, 2013).

6. Prevention and treatment of oxidative stress

6.1 Antioxidant-rich diet

Eating foods rich in polyphenols, vitamins, and minerals can reduce oxidative stress. The best sources of antioxidants include:
• Berries, grapes, green tea (flavonoids)
• Leafy vegetables (carotenoids)
• Nuts and seeds (vitamin E)

6.2 Antioxidant supplementation

In case of antioxidant deficiencies, supplementation with vitamin C, E, coenzyme Q10 or resveratrol may be indicated (Lobo et al., 2010).

6.3 Lifestyle changes
• Regular physical activity of moderate intensity reduces the level of oxidative stress (Radak et al., 2013).
• Avoiding smoking and exposure to air pollution reduces the production of ROS.

7. Summary

Oxidative stress is a significant risk factor for the development of chronic diseases. Controlling it through a healthy diet, physical activity and reducing environmental factors can significantly contribute to improving health and slowing down the aging process. Modern research focuses on finding new methods to counteract the effects of oxidative stress, which may be crucial in preventing many diseases.