Every day, the body is subjected to a variety of stresses from its surroundings: pollution, muscle activity during physical labour or a sports activity, tissue inflammation, ageing, stress, and so on.
These aggressions caused by our surroundings lead to the production of free radicals, which can destroy our cells and damage our body; in practical terms, this means poor recovery, fatigue, injuries.
Physical activity increases the production of free radicals. But not to worry: at the same time, the body raises its defences by producing antioxidants to protect itself (1). Even so, those who do not get enough antioxidants through their diet, will not be as capable of protecting themselves against free radicals.
Presenting antioxidants
Antioxidants are molecules that can be both produced by the body and introduced through our diet.
Indeed, buried in the message “eat 5 fruits and vegetables per day” disseminated by the PNNS (2) are recommendations to get antioxidants through this category of food.
Antioxidants are present in food in a variety of forms: vitamins C, E, A, Omega-3s, zinc, and many other lesser-known micronutrients.
What is the role of antioxidants in the body?
One of the main roles mentioned in the SU.VI.MAX study (3) is a reduction in the risk of the onset of cancer and cardiovascular diseases in humans thanks to regular consumption of fruits and vegetables (rich in antioxidants and fibres).
Antioxidants also play the role of protecting cells by stopping the harmful action of free radicals (those generated when the body is under stress).
Antioxidants such as vitamin E and the Omega-3s found in oily fish and dressing oils help, for instance, lower inflammation and allergies…
Antioxidants in food
The best-known antioxidants are:
• ß-Carotene (provitamin A) is found mainly in bright, orange-coloured fruits and vegetables, such as carrots, apricots, sweet potatoes, red peppers or mangos.
• Ascorbic acid (vitamin C) is found in most fruits, such as oranges, blackcurrants, strawberries, while very large quantities are found in red peppers as well.
• Tocopherol (vitamin E) is abundant in wheat germ, olive oil, sunflower oil, walnuts, almonds, avocado or egg yolk!
• Polyphenols and lycopene. These include flavonoids (widespread among plants), tannins (found in cocoa, coffee, tea, grapes, etc.), anthocyanins (especially red berries) and phenolic acids (found in cereals, fruits and vegetables).
Similarly, starting with the amino acid cysteine, our body can produce a powerful antioxidant called α-lipoic acid or lipoate.
Foods that are sources of cysteine include: brewer’s yeast, wheat germ, garlic, onions, Brussels sprouts, broccoli, dairy products, walnuts, seeds, fonio, seafood, fish, eggs, meat.
The “antioxidant strength” of a food
The “antioxidant strength” of a food, i.e. its ability to withstand oxidation, is expressed using a value called the ORAC unit (Oxygen Radical Absorbance Capacity).
You can find the ORAC indices for hundreds of foods in some of the literature.
ORAC antioxidant activity of various plants, according to the USDA
| Consumed part | ORAC average (μmol TE/100 g) |
|---|---|
| Turmeric | 127,068 |
| Walnuts, English walnut kernels | 13,541 |
| Artichoke, raw heart | 6,552 |
| Plum, fresh | 6,100 |
Red wine, Cabernet Sauvignon | 4,523 |
| Pomegranate, fresh | 4,479 |
| Strawberry, fresh | 4,302 |
| Granny Smith apple, fresh, with peel | 3,898 |
| Goji | 3,290 |
| Red cabbage, boiled | 3,145 |
| Green tea, infused leaves | 1,253 |
Free radicals and oxidative stress
Free radicals are created by the degradation of oxygen by our cells. They are responsible for cellular ageing. Indeed, they attack the body’s tissues, degrading molecules such as DNA, proteins, lipids, etc. This is oxidative stress.
As oxygen consumption increases during physical exercise, so does the production of free radicals. Eating foods that contain antioxidants is therefore essential for athletes to counter oxidative stress.
The importance of antioxidants for athletes
To understand the importance of antioxidants for athletes, let’s start from this principle: the more the body takes in oxygen, the more it generates free radicals, the more it will need antioxidants to fight against them.
Athletes who practise regularly and/or intensively, will therefore have a greater need for antioxidants if they want to avoid problems, especially if they don’t consume enough fruits and vegetables. It is therefore important to ensure a varied, balanced diet, with enough fruits and vegetables.
Our tips to optimise the intake of antioxidants
• Eat enough fruits and vegetables, as varied as possible.
• Alternate between raw and cooked fruits and vegetables: cooking can indeed waste up to 30% of the vitamins and minerals present in these plants (including our precious antioxidants).
• Switch up the oils you use: rapeseed, linseed, walnut oils for dressing, and olive, sunflower oils for cooking.
• Don’t hesitate to add some zest to your cooking with some turmeric, curry, parsley and other herbs and spices rich in antioxidants.
• Some sports products are labelled “antioxidant” due their vitamin and mineral content (vitamins C, E, Zinc). They can help cover your needs if your diet is not sufficiently varied, or during times of major physical effort.
Notes and references:
(1) UBMB Life. 2000 Oct-Nov; 50(4-5):271-7. Free radicals in exhaustive physical exercise: mechanism of production, and protection by antioxidants.
(2) The Programme National Nutrition Santé – or the French National Nutrition and Health Programme, launched in 2001 – is a public health plan aimed at improving the state of health of the population by focusing on one of its major decisive factors: nutrition.
(3) SU.VI.MAX: A study conducted from March 1994 on 13,017 men and women between 35 and 60 years of age over a period of 8 years. Its results were published in July 2003.