I got interested in the oxidation mechanism, so that I could understand why we are constantly being advised to consume antioxidants. Why are they so important to our health ?
A free radical is a chemical species (atom or molecule) whose number of electrons does not correspond to a stable configuration. Here are some examples of stable species :
- O2 (oxygen)
- H + (hydrogen ion)
- HO- (hydroxide)
Oxygen is electrically neutral, but the others not. Yet the 3 chemical species are stable. In order for a chemical species to become a free radical, a disturbance must happen, which alters its stable configuration. The number of electrons then becomes different than the stable version.
Let’s take the most famous example, oxygen :
Small dots represent electrons (negative electric charge). With 6 electrons on the outer layer, each atom is neutral, but above all : stable. If an external element forcibly gives it an extra electron. It then becomes a free radical, named “superoxide”.
The latter is then unstable, with a short lifespan. But above all, it will try to stabilize by sticking to the elements around it, and by reacting with them. This consequently forms new chemical species, among which free radicals, and the reaction propagates so forth as a chain.
Oxidative stress is an attack caused by a reactive oxygen species. We will by the way notice the common prefix “oxy” (oxidation / oxygen) ! The following free radicals thus cause oxidative stress :
- the superoxide anion (O2•-)
- hydrogen peroxide (H2O2)
- the hydroxyl radical (HO•)
When free radicals of an oxygen species attack a cell, they damage its membrane, its proteins, and even its DNA ! The cell is then oxidized : it cannot function properly, and dies. When its DNA is affected, the disrupted cell can even become a “mutant” cell, and therefore potentially a cancerous cell.
The causes can be external or internal. The most famous are :
- Metabolism (energy production – in mitochondria – releases free radicals)
- Drugs and chemicals
- UV rays
- Inflammation / Infection / Injury
When free radicals aren’t neutralized (by the antioxidants that we will see later), the consequences may be dramatic :
- Peroxidation of lipids
- Cell oxidation
- DNA (mutant cells -> cancer)
- Damage to connective tissue and collagen (used for tissue repair)
- Cardiovascular illnesses
- Autoimmune diseases
We have just seen that free radicals are harmful to our body. The good news is that our body contains many antioxidants, which can counteract this oxidation mechanism. These antioxidants are mainly produced by the body itself, but they can also come from our diet, as an additional help.
They don’t all have exactly the same specificities or properties, but they all have the same goal : to make free radicals stable again, so that they no longer harm the body. Some will target some free radicals in particular, or some parts of the cell (membrane, mitochondria, etc.). Thanks to their specificities, they complement each other.
Oxidation and anti-oxidation permanently take place in our body. It’s a vital balance. But it’s not even that simple : oxidation is a natural mechanism that is not always negative. Sometimes the body uses it as a weapon in order to fight against pathogens (eg viruses). On the other hand, if the antioxidants run out, then the cells die, or worse, become cancerous. This is an open door to many pathologies.
Antioxidants will give (or steal) an electron to free radicals in order to stabilize and repair them. Their power lies in the fact that they can give up electrons without becoming a free radical themselves (there are however some limits to that).
We could dedicate an entire article to antioxidants. As for food, they are naturally present in fruits and vegetables, green tea, berries, etc. Some spices, such as turmeric, are also a good antioxidant source.
- Vitamins A, C, E, B complex
- CoQ10 (made by our body)
Oxidative stress damages cells (proteins, membrane and DNA). If these disruptions are not controlled by antioxidants, the body goes to plan B : an inflammatory reaction is triggered. An imbalance between free radicals and antioxidants can consequently lead to systemic chronic inflammation (generalized).
Although my explanation is a little simplistic, you must keep in mind that oxidative stress and chronic inflammation are two mechanisms that are often seen together. It would therefore be clever to combine a diet that is both anti-inflammatory and anti-oxidant.
Much like chronic inflammation, you never know if excess of oxidative stress is a cause or consequence of body disorders. What we know, however, is that taking antioxidants (drugs or food) protects us from accelerated aging triggered by the oxidation of our precious cells.
While waiting for an article dedicated to an anti-oxidant diet, here are my two favorites : turmeric and green tea. And you, what is your secret antioxidant ?