Antioxidants are vitamins, minerals and other chemicals that help protect cells from harmful substances that occur during the normal metabolism process.
It has been observed that diets rich in some antioxidants protect against the development of coronary heart diseases, strokes, some cancers and ailments associated with old age.
So we should consume as many antioxidants as possible, right? Even supplements?
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Probably not.
Although some antioxidants can protect healthy cells from DNA damage, we still do not fully understand all their health effects.
So, while it's a good idea to eat a wide variety of antioxidant-rich foods, the opinion of experts is that most people do not benefit from supplements.
How do antioxidants work?
Image caption To the piece of meat on the left, a few minutes ago they threw a chemical that destroys vitamin E, which prevented oxidation.
Oxidation is a normal chemical process in our body that produces unstable molecules known as free radicals.
In small quantities, these radicals are useful because they play an important role in the normal processes of cells.
But in large quantities, they can cause cell damage and impair the functioning of cells, a process known as "oxidative stress."
We use antioxidants such as vitamin C and beta-carotene to prevent oxidative stress and protect the cells of the body.
Antioxidants do that by picking up electrons from free radicals, which effectively neutralizes them.
What foods do we get antioxidants from?
Click on the words to find out
Selenium
Selenium is a mineral present in the soil. It is important for the normal functioning of the reproductive and immune systems, as well as the use of iodine by the thyroid. Good sources: fish, seafood, red meats, eggs, wheat germ and Brazil nuts.
Vitamin C
Vitamin C is an antioxidant found in many foods, especially citrus fruits and berries, and in green leafy vegetables. It is particularly important for the normal structure, functioning and healing of body tissues, in processes such as the formation of collagen. In some countries, smokers are advised to consume vitamin C. It also helps to absorb iron.
Vitamin E
Vitamin E is a lipid-soluble antioxidant and is particularly suitable to protect the body against oxidative reactions involving fat. All body cells have a thin layer of fat vulnerable to attack by free radicals. Vitamin E intercepts radicals to prevent damage and maintain the integrity of the cell. Sources rich in this vitamin include nuts, seeds and vegetable oils.
Carotenoids
Carotenoids are plant compounds such as beta-carotene, lutein and lycopene, which give fruits, vegetables and yellow, red and orange color. They help strengthen the immune system. The deeper the color, the greater the concentration. Good sources: apricots, mangoes, passion fruit, carrot, red paprika, sweet potato and tomatoes. Bright orange beta-carotenes like those in carrots may have additional benefits as they become vitamin A.
Phenolic compounds
Phenolic compounds are a large group of plant chemicals with antioxidant properties. They include flavonoids such as quercetin, which is found in onions, tea, red wine and chocolate; curcumin, found in turmeric and mustard; tannins, found in green and red tea; Isoflavones, which is found in soy milk, tofu and miso; and lignans, in the flax seed and other grains.
Research in the last decade has shown that consuming foods rich in antioxidants - such as fruits, vegetables, legumes and grains - has a beneficial effect on our overall health. But it is important to note that the antioxidant content in foods and beverages varies a lot and does not equal their potential impact on the body.
The supplements, a waste of time?
Most clinical trials to date have not found any evidence that taking individual antioxidants or combinations of them can offer healthy people protection against the disease.
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According to Tom Sanders, director of the division of diabetes and nutritional sciences at King's College London, taking antioxidant supplements can be even harmful to health, particularly for smokers.
And the Cochrane Collaboration, an international group that reviews evidence of health interventions, also supports the view that antioxidant supplements can be more harmful than beneficial.
In 2012, he conducted a review of 78 clinical trials of antioxidant supplements and found no evidence that it could be used as primary or secondary prevention against the disease.
A study carried out in the 1990s with Finnish men smokers found that those taking high doses of beta-carotene had a higher risk of developing lung cancer. Research on the effects of vitamin E antioxidant supplements has been linked to a type of stroke and possibly prostate cancer.
Luckily, nature provides a balanced package of antioxidants and there is certainly no evidence that eating too many fruits and vegetables can be bad.
- Get a rainbow
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- A balanced diet
Specialists recommend eating more food from plants, such as vegetables, fruits, grains and legumes, which are not only rich in antioxidants but also a good source of fiber.
But, how much is enough?
According to the British Dietetic Association, eating 400g of fruits and vegetables a day can help reduce the risk of health problems such as high blood pressure, obesity and some cancers.
Dietitian Felicity Lyons, spokeswoman for that agency, says that each antioxidant plays its particular role in the body, so consuming too much of one type in general does not help.
In addition, he advises to try to consume less processed foods and cook more at home.