Bien-être 22/03/2021
A full dose of antioxidants, yes but why?
Praised for many years, antioxidants are considered essential allies in fighting certain diseases, limiting the effects of aging, and supporting the immune system. Naturally present in food, antioxidants are indispensable for our health and well-being. But why is it so important to consume them? And what role do antioxidants play in our health? Analysis.
What is oxidative stress?
Also called oxidative stress, oxidative stress corresponds to an attack on our cells by free radicals. Our body has natural weapons to fight these molecules, notably by producing antioxidant enzymes, such as glutathione, catalase, or superoxide dismutase. However, if free radicals are in excess, the body is overloaded: this is called oxidative stress.
Free radicals at the origin of oxidative stress
All living beings need oxygen to live, but they must also protect themselves from it because it can be toxic. At the origin: free radicals, highly reactive oxygen molecules.
Our cells contain mitochondria, which provide the energy necessary for the cells. The more energy a cell needs for its functioning, the more mitochondria it contains. In these mitochondria take place a series of very complex chemical reactions, such as the combustion of sugars and fats which releases energy. Unfortunately, the reaction chain of our mitochondria is imperfect and leads to the formation of reactive oxygen species, which include free radicals.
Our environment as an accelerator of the aging of our cells
Free radicals are thus formed during various biological processes. But their production is increased under the effect of external factors (pollution, UV rays, etc.), which can lead to a situation of oxidative stress, and therefore to the aging of our cells (see our article on the power of antioxidants).
Antioxidants to the rescue!
To protect itself from the toxic effects of these free radicals, the body has developed antioxidant defense systems composed of enzymes, vitamins, trace elements, and proteins. But when oxidative stress is too high, it is essential to provide our body with new sources of antioxidants through diet. Antioxidants present in foods (mainly vitamins A, C, and E, polyphenols, and minerals) are agents that help prevent, delay, or slow down the oxidation process.
How do antioxidants fight free radicals?
Once the oxidation reaction in our body is initiated, it must be stopped. Without the intervention of antioxidants, the production of free radicals would lead to the aging of our cells, and consequently the appearance of many diseases.
Let's take the example of a fruit, such as a banana, apple, or avocado, which turns brown once cut. How to explain this phenomenon? For this enzymatic browning process to occur, it needs 3 elements:
- Oxygen
- A special enzyme called polyphenol oxidase (PPO)
- Polyphenols, also called phenolic compounds
Enzymes and polyphenols are found inside the fruit's cells, in small compartments. They never touch each other. But when the fruit is cut or bitten, the cells are damaged. They are then exposed to air, which contains oxygen. This causes the oxidation reaction that leads to enzymatic browning.
Antioxidants therefore have the mission to block the production of these free radicals. For example, by pouring lemon juice on the fruit, the vitamin C it contains (a powerful antioxidant) will modify the chemical composition of the molecules and slow down the aging process. This phenomenon is exactly the same in our body: by neutralizing excess free radicals in the body, antioxidants will block their production to prevent premature aging of our cells and promote the natural regeneration process.
Why consume antioxidants?
Antioxidants are essential to maintain optimal health, and this for several reasons.
To prevent the harmful effects of free radicals
In small amounts, free radicals help fight viruses, bacteria, and microbes. Otherwise, they can damage cells and accelerate their aging.
To fight oxidative stress
Oxidative stress can promote the development of diseases such as atherosclerosis, arthritis, cardiovascular disorders, and premature skin aging.
To stock up on vitamins
Antioxidants are a source of vitamins that help the body fight various diseases. A regular and sufficient intake of vitamins allows good blood fluidity, accelerates cell renewal, increases vascularization, stimulates the immune system, and improves resistance to infections.
To fight skin aging: vitamin C
Oxidative stress is the main cause of skin aging. It creates an inflammatory state and affects the upper layers of the epidermis. It is recommended to favor foods rich in vitamin C, as it helps collagen and elastin fibers fight excess free radicals, thus preventing the premature appearance of wrinkles and age spots.
For better sun tolerance: beta-carotene
This antioxidant from the carotenoid family is an excellent tanning activator. It increases the skin's tolerance to sunburn. By promoting the synthesis of melanin responsible for tanning, beta-carotene prepares the skin for the sun and the aggression represented by ultraviolet rays.
To preserve memory: vitamin E
Neuron membranes are composed of unsaturated fatty acids that are easily oxidized. This oxidation can accelerate brain aging. Several scientific studies have shown that a reduction in vitamin E levels in the brain would promote the progression of neurodegenerative diseases, such as Alzheimer's disease.
To stimulate immunity: zinc
Zinc stimulates white blood cells responsible for fighting infections and neutralizes free radicals generated by inflammation sites. Zinc deficiency could be involved in various chronic diseases in which inflammation plays an important role, such as cardiovascular diseases and diabetes.
To prevent chronic inflammation: polyphenols
Studies show that polyphenol consumption has a significant effect on reducing inflammatory stress, which is at the origin of many diseases such as diabetes, Alzheimer's, or cardiovascular diseases. They would thus help reduce the release of pro-inflammatory mediators in people at risk of chronic inflammation.
Sources
The Roles of Vitamin C in Skin Health, Juliet M. Pullar, Anitra C. Carr and Margreet C. M. Vissert, Nutrients, 2017.
B-Carotene and other carotenoids in protection from sunlight, Wilhelm Stahl, Helmut Sies, The American Journal of Clinical Nutrition, Volume 96, Issue 5, November 2012.
Dietary Sources of Lutein and Zeaxanthin Carotenoids and Their Role in Eye Health, El-Sayed M. Abdel-Aal, Humayoun Akhtar, Khalid Zaheer, Rashida Ali, Nutrients, 2013.
Effects of Vitamin E on Cognitive Performance during Ageing and in Alzheimer’s Disease, Giorgio La Fata, Peter Weber, Nutrients, 2014.
Zinc metabolism with special reference to its role in immunity, M.T. Kidd, P.R. Ferket and M.A. Qureshi, World’s Poultry Science Journal, 2019.
Oxidative Stress and Inflammation : What Polyphenols Can Do for Us? Tarique Hussain, Bie Tan, Yulong Yin, François Blachier, and al., Oxid Med Cell Longev, 2016.
