Oxidative stress occurs when cellular antioxidant defenses are too low to compensate for reactive oxygen radicals: As intermediates of metabolism, free radicals are constantly produced in every cell of the human body. The oxygen compounds with unpaired electrons strive to snatch electrons from another atom or molecule. They react with these and form new radicals, which in turn also snatch electrons from other substances, and in a chain reaction there is a constant increase in the number of radicals in the body (= oxidative stress).
Physiological formation of reactive oxygen species (ROS).
- Mitochondrial respiration (a cell requires 1012 molecules of O2 per day).
- In the activation of granulocytes and macrophages (phagocytes).
- Fenton reaction catalyzed by iron compounds oxidation of organic substrates with hydrogen peroxide in acidic medium. Fenton-like reactions can also occur with the participation of other low-valent metal complexes such as Cu(II), Ti(III), Cr(II), or Co(II). The Fenton reaction is considered to be one of the major sources of reactive oxygen species in the cell (= oxidative stress)
- By oxidases such as for example monoaminooxidase, xanthine oxidase, L-aminooxidase, tyrosine hydrolase, flavin oxidase, etc.
- In arachidonic acid metabolism
Cells maintain homeostasis (steady state; equilibrium) between formation and degradation of reactive oxygen species (ROS). Increased concentrations of ROS lead to structural and functional changes in proteins, lipids and nucleic acids.
Causes of oxidative stress
Biographic causes
- Genetic stress caused by parents, grandparents (genetic individuality, which means genetically determined different endowment e.g. with radical scavenging enzymes).
- Age
Behavioral causes
- Diet low in vital nutrients (few cereal products, less than 5 servings of vegetables and fruits (400-800 g/day), little milk and dairy products, less than one to two fish per week, etc).
- Malnutrition and malnutrition including over- and undernutrition.
- Smoking the substances inhaled in a single puff from a cigarette, form 1015 free radicals in the lungs a hundred times more than we ourselves have body cells. When detoxifying the tar inhaled at the same time, an additional 1014 free radicals are formed.
- UV rays for example sunlight, solarium
- Extreme physical labor
- Competitive and high-performance sports
Causes related to disease
- Acute inflammation
- Atherosclerosis
- Diabetes mellitus
- Hemochromatosis
- Pulmonary diseases such as Adult Respiratory Distress Syndrome (ARDS), bronchial asthma, emphysema, Chronic Obstructive Pulmonary Disease (COPD).
- Neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis (ALS).
Laboratory diagnoses
- Malonaldehyde (MDA), 4-hydroxy-2-nonenal (HNE) and 2-propenal (acrolein) indirect indicators of oxidative stress (as end products of lipid peroxidation).
Drugs
- Hormonal contraceptives in 40- to 48-year-old women who used oral contraceptives, significantly increased peroxidation of lipids was recorded. This may be indicative of increased cardio-vascular risk.
X-rays
- Irradiation for tumor diseases
- Ionizing rays
Chemotherapies
Surgeries
Environmental pollution and intoxications
