Praised for many years, antioxidants are considered essential to fight against certain diseases, limit the effects of aging and support the immune system. Naturally present in the diet, antioxidants are essential to our health and well-being. But why is it so important to consume them? And what role do antioxidants play in our health? Let's find out.
Also called oxidative stress, oxidative stress corresponds to an aggression of our cells by free radicals. Our body has natural weapons to fight against these molecules, in particular 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.
All living things need oxygen to live, but they must also protect themselves from it because it can be toxic. At the origin: free radicals, very reactive oxygen molecules.
Our cells contain mitochondria, which provide energy to the cells. The more energy a cell needs to function, the more mitochondria it contains. In these mitochondria, a series of very complicated chemical reactions take place, such as the burning of sugars and fats, which releases energy. Unfortunately, the reaction chain in our mitochondria is imperfect and leads to the formation of reactive oxygen species, which include free radicals.
Free radicals are therefore formed during various biological processes. But their production is increased by external factors (pollution, UV rays, etc.), which can lead to a situation of oxidative stress, and thus to the aging of our cells (see our article on the power of antioxidants).
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 great, it is essential to provide our bodies with new sources ofantioxidants through the diet. Antioxidants present in food (mainly vitamins A, C and E, polyphenols and minerals) are agents that can prevent, delay or slow down the oxidation process.
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 to the onset of many diseases.
Let's take the example of a fruit, such as a banana, an apple or an avocado, which once cut starts to turn brown. How can we explain this phenomenon? For this enzymatic browning process to take place, it needs 3 elements:
The enzymes and polyphenols are located inside the fruit cells, in small compartments. So they never touch each other. But when you cut the fruit or bite it, you damage the cells. The cells are then exposed to the air, which contains oxygen. This causes the oxidation reaction that leads to enzymatic browning.
Antioxidants have the task of blocking the production of these free radicals. By pouring lemon juice on the fruit, for example, 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 organism: by neutralizing the free radicals in excess in the body, the antioxidants will block their production to avoid the premature ageing of our cells and to support the natural regeneration process.
In small amounts, free radicals help fight viruses, bacteria and microbes. In the opposite case, they can damage cells and accelerate their aging.
Oxidative stress can promote the development of diseases such as atherosclerosis, arthritis, cardiovascular disorders and premature aging of the skin.
Antioxidants are a source of vitamins that help the body fight against various diseases. A regular and sufficient supply of vitamins allows a good fluidification of the blood, the acceleration of the cellular renewal, the increase of the vascularization, the stimulation of the immune system and a better resistance against the infections.
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 favour foods rich in vitamin C, as it helps collagen and elastin fibres to fight against excess free radicals, thus preventing the premature appearance of wrinkles and age spots.
This antioxidant of the carotenoid family is an excellent tanning activator. It increases the skin's tolerance to sunburn. By promoting the synthesis of melanin, which is the source of tanning, beta-carotene prepares the skin for the sun and the aggression represented by ultraviolet rays.
The membranes of neurons are composed of unsaturated fatty acids that are easily oxidized. This oxidation is therefore likely to accelerate brain ageing. Several scientific studies have shown that a reduction in the level of vitamin E in the brain favours the progression of neurodegenerative diseases, such as Alzheimer's disease.
Zinc stimulates the white blood cells that fight infection and neutralizes the free radicals generated by inflammation. Zinc deficiency may be involved in various chronic diseases in which inflammation plays an important role, such as cardiovascular disease and diabetes.
Studies show that the consumption of polyphenols has a significant effect on reducing inflammatory stress, which is the cause of many diseases such as diabetes, Alzheimer's and cardiovascular disease. They would thus contribute to reducing the release of pro-inflammatory mediators in people at risk of chronic inflammation.
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 Amercian 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.