Oxidative Stress

Oxidative stress is not an illness, but it may be linked to many pathological conditions. It is a process that occurs in our bodies during normal metabolism. Oxidative stress is related to the presence of harmful and aggressive oxygen radicals that occur during chemical reactions in our tissues. Their existence is inevitable as oxygen is necessary for our life. This however means that oxygen is a potentially harmful substance that damages are tissue when present in high concentration. Normal air contains 21% of oxygen and this, of course, causes no harm. It should be added that a huge amount of free radicals is formed in the body during smoking.

Oxygen radicals

Oxygen radicals are elements that contain one or more unpaired electrons. The radicals are unstable and they tend to take electrons from other molecules changing their structure and thus damaging both cell membranes and intracellular structures including the nuclei. The cell damage may result in cell necrosis or mutations and every mutation increases the risk of cancer diseases.


Oxygen radicals play important role in formation and development of various pathological conditions including atherosclerosis and its complications, COPD and pulmonary emphysema, malignant cancers and type 2 diabetes. It is assumed that everyday production of oxygen radicals also plays an important role in the process of aging. 


Fortunately, our body has a number of defensive enzymes and other substances that transform the oxygen radicals to harmless substances. The result is a dynamic process of continuous formation and degradation of free oxygen radicals. We can positively influence the situation by reducing the radical production (smoking cessation) and increasing the intake of so-called antioxidants that are substances helping to remove the oxygen radicals. The important antioxidants include:

Vitamin E

This is a fat-soluble vitamin, which is a powerful antioxidant. High amount of vitamin E is present in cereals, oatmeal, vegetable oil, nuts, olives, spinach and egg yolks.

Vitamin C

Vitamin C is among others also an important antioxidant. It is present in fruit (lemons, oranges, and currants), tomatoes and potatoes.


Selenium is a powerful antioxidant, which can be found in plants growing in soil rich in selenium, in nuts and in seafood. Selenium deficiency probably indirectly increases occurrence of cancers, but on the other hand, the excessive intake of selenium may have similar effects. So it is important no to overdose self.


Silicon is a trace element, which not only combats the oxidative stress, but also allows proper function of the connective tissue.


This antioxidant is a substance, from which vitamin A is formed. Beta-carotene occurs in egg yolk, fruits and vegetables (kale, spinach, carrots, mango, peaches and broccoli).


Bilirubin is a substance produced in the human body during disintegration of blood pigment hemoglobin. If this substance accumulates in the body, it causes jaundice (yellow color of the skin and mucous membranes). However, bilirubin also acts as an antioxidant and therefore, people with long-term slightly elevated serum bilirubin in Gilbert's syndrome are in lower risk of atherosclerosis and its cardiovascular complications.


The question is how to approach this issue and if it is a good idea to regularly take the dietary supplements with antioxidants. I would urge to be cautious. It is really important to have a sufficient intake of antioxidants, but it is advisable to take them in rich and healthy diet, especially in fruit and vegetables.


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Contact: jiri.stefanek@seznam.cz
 Sources: basic text sources