Oxidative stress is, by definition, the harmful impact caused by excessive amounts of free radicals on the cells and tissues in our body. This oxidative stress from free radicals can trigger the onset of cardiovascular diseases, tumors, diabetes, and its complications (retinopathy, arterial disease, neuropathy, diabetic foot, nephropathy, etc.) and other chronic diseases.
What are free radicals?
Free radicals are particularly aggressive, unstable molecules that are generated incessantly in our body as by-products of the natural processes of cells. They are responsible for the cellular oxidation that causes aging and pose a threat to our health by putting a strain on our antioxidant defenses. Free radicals are formed as a waste product of the natural metabolic processes that use oxygen (O2) as fuel to produce energy (oxidation). For this reason, they are also called “reactive oxygen species” or ROS. Among the most common types of ROS are the superoxide anion (O• 2 – ) and the hydroxyl radical (• OH). Oxygen has a corrosive nature, and the part that is not consumed accumulates in these highly reactive molecules which trigger dangerous chain reactions.
Why are free radicals so aggressive and dangerous?
Chemically, a “free radical” is a particle that possesses one or more uncoupled electrons on its outer layer. The presence of an unpaired electron makes a molecule highly unstable. Each free radical in practice has lost the chemical “partner” to which it was linked due to metabolic processes or many other factors (pollution, UVA rays, prolonged stress, smoking, etc.) and these particles immediately and energetically go hunting for a new “partner” to recover their missing electron.
This hunt is aggressive, indiscriminate, and very fast (fractions of a second) and in the process attack fundamental parts of other cells. This attack can affect fats called lipid peroxidation or proteins present on cell membranes and in internal organelles of the cell or nucleic acids (DNA and RNA) stored in the cell nucleus.
Is it true that a chain reaction is created?
Yes, describing this process as a chain reaction is an accurate description. To regain their stability, free radicals steal an electron from another molecule. Once robbed of their electron, this molecule is destabilized turning it into a free radical, so it attempts to steal an electron from the next molecule and so on. In this way a chain of reaction is created called “oxidative stress” in which free radicals prevail over antioxidant defenses.
It’s a domino effect which spreads very quickly and involve thousands of molecules and, if not stopped in time, damages our cellular structures causing the cells in our bodies degenerate, age prematurely or create the onset of various diseases.
What are the causes that induce an increase in the production of free radicals?
The causes can be both external and internal to the body. External causes include:
- Certain physical agents (e.g., ultraviolet, and ionizing radiation)
- Numerous chemical agents (e.g., hydrocarbons, herbicides, food contaminants, certain medicines)
- Certain infectious agents (e.g., viruses and bacteria)
Internal causes include:
- Exaggerated acceleration of cellular metabolism (e.g., after intense and prolonged physical exertion, without adequate training)
- Numerous diseases (obesity, diabetes, hypertension etc.)
Are free radicals making us age?
Back in 1956, Denham Harman, chemist, biologist, and physician at the University of Nebraska, proposed the theory of aging based on free radicals, which proposed that over the years, these compounds excessively accumulate in cells (oxidative stress) and cause a powerful oxidizing effect that is harmful to all our cells.
This theory of cellular oxidation is now unanimously accepted by the international scientific community. The continuous oxidizing action of free radicals is evident above all in the premature aging of cells and has been associated with the onset of various diseases such as diabetes and its complications (neuropathy, nephropathy, angiopathy, retinopathy), some diseases of the cardiovascular system, multiple sclerosis, rheumatoid arthritis, pulmonary emphysema, cataracts, Parkinson’s disease and Alzheimer’s, tumors and many others.
How does our body defend itself from the attack of free radicals?
Our body is able to defend itself from the presence of free radicals and cellular oxidation thanks to a system of natural antioxidant substances, which can neutralize the harmful effect of free radicals by providing them with the electron they are missing-thus stopping the chain reaction. Other substances that play an important antioxidant role we get through food. The main ones are:
- Plant pigments: polyphenols, bioflavonoids, anthocyanins
- Vitamins: vitamin C (ascorbic acid), vitamin E (α- or γ-tocopherol), beta-carotene (also called provitamin A, as it is the precursor from which this vitamin is formed)
- Micronutrients: selenium, copper, zinc, others
- Enzymes: glutathione, coenzyme Q10, others
- Other substances: melatonin, uric acid etc.
In our body, therefore, there is a delicate balance between production (external and internal) and “disposal” of free radicals by antioxidant agents. These can act synergistically both individually and in cooperation with each other. Only a complete and balanced diet can guarantee effective antioxidant protection. Experts recommend consuming least 5-6 servings of fresh, seasonal fruit, and vegetables daily and to follow a diet low in saturated fats and hydrogenated fats, both of which are recognized sources of free radicals.
In addition to a poor diet, what other factors can promote oxidative stress?
Numerous factors contribute to the disruption of the balance between the production and elimination of free radicals, determining the onset of so-called oxidative stress. Among the most common factors are:
- Inflammation
- Cigarette smoke (tobacco is a veritable mine of toxic substances)
- Intense and prolonged psycho-physical stress
- High alcohol consumption
- Diets too rich in protein and saturated animal fats
- The presence of an excess of iron (which is capable of activating harmful chemical reactions)
- Exposure to polluted environments, ionizing and ultraviolet radiation (excess ozone and UVA and UVB rays)
- Overly intense physical activity
- Certain medications
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