The oxidative stress is a physiological process that occurs in every cell in the body: it is the set of reactions that lead to the production of free radicals and which are necessary because a number of vital functions, for example the defense against infections, occur correctly.
However, when the level of free radicals present in our body exceeds a certain threshold, it can damage cellular structures and give rise to aging and even serious pathologies, such as neurodegenerative and cardiovascular diseases: this happens when the balance between the production of free radicals and their elimination by antioxidants breaks down, creating a surplus of potentially harmful free radicals.
Let’s see in detail what is oxidative stress, what are the risk factors, the role of antioxidants and the correct habits to adopt, at the table and not only.
Oxidative stress: What it is?
By oxidative stress, we mean the set of biochemical reactions that lead to an overproduction of free radicals in the body’s cells and tissues.
Free radicals are unstable compounds that “capture” an electron from other molecules (oxidation reaction) making them unstable in turn and thus triggering a cascade mechanism.
However, oxidative stress is a natural and physiological phenomenon that occurs in every cell: in fact free radicals are produced inside the mitochondria (cellular organelle used as an “energy center”) following reactions necessary for the production of energy or in all those tissues with high oxygen consumption, for example muscle.
Furthermore, oxidative stress is the result not only of free radicals normally produced by the body: in fact, those deriving from the external environment must be added to these.
Here are some of the factors that increase the stress faced by the body every day …
- Excess alcohol and physical activity
- Heavy metals
- Cigarette smoke.
Free radicals and oxidative stress
The most studied free radicals are ROS (Reactive Oxygen Species). They are reactive oxygen species, among which we find …
- The superoxide anion (O 2- )
- Hydrogen peroxide (H 2 O 2) which can give rise to the hydroxyl radical (OH · ¯ ).
These molecules are produced by normal cellular metabolism, but they are particularly “reactive” because they have a free electron that is “ready” to interact with other molecules.
There is a level of ROS that is essential for maintaining the body’s homeostasis. For example, ROS generated by phagocytic cells are an essential defense for fighting infections, just as ROS produced in response to growth factor stimuli are physiologically involved in the control of cell proliferation.
An increase in the ROS level can however lead to damage to various cellular components (DNA, proteins, lipids).
For this reason, in order to maintain balance, there is an endogenous antioxidant defense system consisting of different enzymes (superoxide dismutase or SOD, Catalase, Glutathione peroxidase).
Causes and risk factors
The balance between ROS production and antioxidant agents determines the level of oxidative stress.
If stress is excessive, it can lead to damage to cellular structures such as …
- The membranes
High oxidative stress can be determined by an excess of pro-oxidant agents, such as …
- A high rate of metabolic activity
- Excessive sport
- Deficiency of defenses (low level of antioxidants)
- Susceptibility of free radical targets.
Risks from exposure to chemicals and radiation
There may also be other factors that increase the stress the body faces. Those who work closely with chemicals or radiation must be very careful not to accumulate excessive exposures.
A typical example is those who work in radiology: these people are, in fact, easily exposed to ionizing radiation which, due to a dose-dependent mechanism, can induce modification in the DNA sequence with mutagenic effects on cells.
Another example is the biologists who work in the laboratory: in fact, in cellular colors many compounds are used that can harm health. Ethidium bromide (used in molecular biology) is one of the most glaring examples: it is an intercalating agent of DNA that can exert carcinogenic effects on those who come into contact with it.
This highlights how we are continually exposed to cellular stress and how antioxidants and endogenous defense mechanisms play a crucial role in defending us from disease development.
Oxidative stress and cellular aging
Aging is a physiological process given by free radicals.
In fact, their interaction with …
- Protein structures (enzyme malfunction)
- Lipid (alteration of cell membranes)
- Fluidic (alteration of glycemic balance)
- With the same DNA (mutagenic effects).
It is responsible for some types of diseases related to aging, such as neurodegenerative and cardiovascular diseases.
For example, an increase in the vascular production of ROS in the vascular walls of patients with arteriosclerosis risk factors has been demonstrated.
Oxidative stress and inflammation
Inflammation means a set of defense mechanisms that come into play to repair damaged tissue.
In fact, whenever a chemical, mechanical, internal or external factor acts, the body creates a repair mechanism to restore normal functionality.
A very common mistake is to see inflammation as something negative, on the contrary it is something necessary and inevitable.
Inflammation is the means through the body repairs itself and allows the survival of the individual: it is the response of the immune system to the stresses that cause suffering to the cells.
We are constantly exposed to external stress (chemical agents, radiation, emotional stress), but also and above all from within.
Our cells die and replicate continuously, both physiologically and after having suffered damage.
It is therefore essential to keep free radicals under control and make sure they are not in excess.
The classic physiological response in inflammation is the excess of white blood cells which produce free radicals through phagocytosis processes, but as long as these are not in excess there is no need to worry.
Short and long term symptoms and complications
Depending on the type and level of ROS, the time of exposure, the level of defense of antioxidants and the repair systems that remedy the damage caused by free radicals, the cells exposed to ROS can:
- Show an increase in proliferation
- Show a cell cycle arrest
- Undergoing senescence (loss of physiological function)
- To undergo programmed cell death (apoptosis).
Diseases associated with oxidative stress
It is known that ROS, in particular the hydroxyl radical OH, induce different damages to the double helix structure of DNA.
Thus ROS, which are generated endogenously or exogenously, could be involved in all stages of carcinogenesis especially if they induce lesions in genes relevant to cancer development (oncogen genes and / or tumor suppressors).
Although the most accepted hypothesis is that ROS are necessary but not sufficient for the development of cancer.
Other diseases associated with oxidative stress are …
- Autoimmune diseases such as rheumatoid arthritis
- Neurodegenerative diseases such as Alzheimer’s or Parkinson’s.
Oxidative stress can induce systemic damage so as to be a contributing factor in the development of food or nutrition related diseases, such as obesity (especially abdominal) or diabetes.
Healthy eating to prevent oxidative stress
A healthy diet and regular, moderate physical activity can modulate the dynamic balance between oxidants and antioxidants.
We have seen how caloric restriction (without malnutrition) can induce reduced metabolic stress in the brain with an improvement in cognitive processes, synaptic plasticity, and neuronal survival.
This is reflected in a slowing of aging and an improvement in life expectancy to decrease the chances of getting sick …
The defense mechanisms against free radicals can be of a nature …
- Enzymatic (superoxide dismutase, catalase, glutathione peroxidase)
- Non-enzymatic (vitamins).
For this reason, foods can modulate our defenses against free radicals either with vitamin compounds such as vitamin E , vitamin C or carotenoids (vitamin A, β-carotene), but also with different antioxidant compounds.
Nutraceuticals with an antioxidant effect
In recent years the business of nutraceuticals (nutritional component with beneficial effects on health) has considerably expanded, but also functional foods (whole food containing one or more nutraceuticals with beneficial health effects).
Examples of nutraceuticals with antioxidant effect are …
- Green tea catechins
- Cocoa anthocyanidins
- Quercitin present in onions
- Soy isoflavones
- Citrus bioflavonoids
- Phenolic esters of coffee and red wine.
In addition to paying attention to food, it is also important to have an eye on how these are prepared.
The cooking methods, in fact, are an important variable in inducing stress to our body.
Barbecuing tends to produce benzopyrene, an aromatic hydrocarbon harmful to health.
During a barbecue, the fall of the fat from the meat can release from the coals this volatile substance, which we also find in food.
The advice is therefore to limit as much as possible the cooking on the grill, or at least cook the meat with all the skin, and then remove it only once cooked.
The skin allows, even if minimally, to “shield” the accumulation of benzopyrene from the meat.
Test to measure oxidative stress
Currently there are various tests for the evaluation of oxidative stress.
Their function is to quantify the dynamic equilibrium that exists in our body between pro-oxidant and anti-oxidant action.
The best way is to analyze stress with various tests in order to quantify both actions (oxidant and antioxidant), which cannot be measured with a single methodology.
- The d-ROMs test is a reliable test in clinical practice that allows, after the separation of the corpuscular component from the fluid component of the blood, to quantify the pro-oxidant capacity of the plasma. This occurs through a direct measurement of hydroperoxides (a species that is part of the ROS).
- To this test it would be good to also combine the BAP test, which is able to determine the blood concentration of the antioxidant compounds. It allows the total measurement of antioxidants such as α-tocopherol or ascorbic acid, but does not provide a measurement on a single molecule.
- It is evident how d-ROMs test and BAP test are complementary and how together they can provide a picture of the general state of health of the organism.
Only once both tests are done, it is possible to take corrective actions on the oxidative balance. In fact, through these tests, you can understand if stress is given by an excess of oxidation and a deficiency of antioxidants.
Care and therapies
A correct diet (varied, colorful, rich in vitamins, fruit and vegetables) and a healthy lifestyle can meet the body’s antioxidant needs.
However, at times it may be necessary to have a supplement appropriately designed to …
- Older people
- Who lives a very stressful time?
A diet high in fat induces an increase in ROS produced by mitochondria in muscle fibers, but if ROS is blocked with an antioxidant, the sensitivity to insulin is increased.
In that case, the administration of antioxidants could increase insulin sensitivity with an improvement in health status.
Sport and oxidative stress
Sport, if done in the right ways and times, can certainly help improve your health.
In sports, however, rest is often not seen as an integral part of training and we tend to go overtraining.
This is a condition that we often find in elite athletes, who have a high metabolic stress dueto the body’s inability to “recover” from stress.
Excessive and continuous training determines an excessive production of free radicals with the consequent inability of the organism to eliminate the accumulated waste.
The continuous search for the best athletic form and performance at all costs is the reason for the increasingly frequent injuries (both muscular and traumatic) among high level athletes.
Sportsmen’s diet to combat oxidative stress
Athletes must follow a healthy and varied diet that can guarantee them the right amount of antioxidants. Sometimes, however, the famous 5 portions of fruit and vegetables may not be enough in subjects with high energy and metabolic needs.
Many athletes use supplements based on …
- C vitamin
They are all substances found in citrus fruits, fruit or vegetables.
This highlights how in athletes’ diets we must take into account not only macronutrients (proteins, carbohydrates and fats), but also micronutrients (vitamins and mineral salts) in order to allow a prompt recovery for the next competition.
Fatigue or weakness are warning signs that show that oxidative and muscular stress is excessive.
Which supplements to fight oxidative stress?
In principle, foods could also cope with daily antioxidant needs and for this reason it is important to take 5 portions of seasoned fruit and vegetables as colorful as possible.
However, industrial processes, the use of pesticides as well as the mineral impoverishment of the soil often do not produce the same antioxidant capacity found in nutritional tables in fruit and vegetables.
For this reason it is often necessary to take supplements in order to restore the body’s physiological antioxidant capacity.
Taking β-carotene supplements, vitamin E, vitamin C and coenzyme Q10 can be of great help in some cases.
The form and route of administration of the supplement are also important.
In fact some formulations can see their bioavailability significantly reduced because they are inactivated by the digestive tract.
For this reason it can also be administered doses of antioxidants for intravenous or sublingual in order to bypass the oral route.
In any case, the advice is to always take such supplements under strict medical supervision.
In fact, liposoluble compounds such as vitamin E and β-carotene can induce toxicity due to their ability to accumulate in tissues, while an excess of vitamin C has shown (contrary to popular belief) an activated pro-oxidant.