Comprendre l'impact des radicaux libres

Understanding the impact of free radicals

Nov 30, 2023

In biochemistry, there are particles called free radicals . They are the origin of many processes in our body, but can also be the precursors of different diseases. Understanding how they work and how to control them is therefore essential.

What are free radicals and how are they formed?

Free radicals are atoms, ions or molecules that have an unpaired electron in their outer shell, making them particularly reactive. To stabilize their structure, they seek to “steal” an electron from other molecules, thus causing a chain of chemical reactions harmful to the body.

The formation of free radicals occurs in two main ways.

First, they can be formed from normal metabolic processes. For example, our bodies produce free radicals during cellular respiration, a vital reaction that produces energy in our cells. The extract of oxygen we breathe combines with the nutrients in our food to create this energy, producing harmful elements like free radicals in the process.

Second, environmental factors and unhealthy lifestyle habits can also contribute to the formation of free radicals. For example, air pollution , alcohol consumption and smoking , radiation exposure , certain types of medications , and even unhealthy diets can all generate free radicals in our bodies.

The different types of free radicals and their sources

Two main categories are oxygenated radicals and non-oxygenated radicals .

Oxygen radicals

As their name suggests, these radicals involve oxygen. This is an important category that includes the hydroxyl radical (•OH) and the superoxide radical (O 2 •−). These radicals are mainly formed during normal metabolic processes, such as cellular respiration where oxygen is used to produce energy.

Non-oxygen radicals

This other category is varied and includes radicals such as the phenyl radical (C 6 H 5 •) and the alkyl radical (R•). These radicals originate from a variety of activities, including exposure to industrial chemicals and consumption of certain medications.

Aside from these internal sources, many environmental factors contribute to the formation of free radicals, such as exposure to UV radiation, air pollution and smoking. An unbalanced diet and stress can also increase the production of free radicals in the body.

Free radicals derived from nitrogen

There are other reactive nitrogen species (RNS) such as nitric oxide radical (-NO) and peroxynitrite (ONOO-), which can react with biological molecules and cause damage. These types of radicals are usually formed during the immune response.

Free radicals, whether of internal or environmental origin, can contribute to an imbalance in the body. This is why understanding their sources and their formation is essential to maintain a good antioxidant balance, protective of your cells.

The consequences of excess free radicals in the body

When free radicals are present in excess in the body, they can cause oxidative stress. It is an imbalance between the production of free radicals and the body's ability to neutralize their harmful effects through antioxidants.

This imbalance can lead to very harmful health outcomes. Free radicals can damage cells, proteins, and even DNA in the body. In addition, they play an important role in the aging process and can contribute to the onset of many diseases.

Diseases linked to oxidative stress

Several chronic diseases have been linked to oxidative stress , including:

  1. Cardiovascular disease: Oxidative stress can lead to atherosclerosis, a condition that hardens and narrows the arteries, increasing the risk of heart attacks and strokes.
  2. Neurodegenerative diseases: Oxidative stress is also associated with diseases such as Alzheimer's and Parkinson's.
  3. Cancer: Damage to DNA by free radicals can lead to mutations, which in turn can lead to the proliferation of cancer cells.
  4. Diseases of aging: Premature tissue wear and tear caused by oxidative stress can contribute to the onset of many age-related diseases, including arthritis.


Free radicals are unstable molecules that can damage our cells by causing oxidative stress . They are both naturally produced by our body during different metabolic processes and also present in our environment due to various external factors such as pollution, tobacco or even poor diet.

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