Antioxidants seem to be everywhere; in superfoods and in skin care products, including chocolate and red wine. Products that contain antioxidants are marketed as essential for good health, with promises to fight diseases and reverse aging. But are they really as good to us as they make us believe?
What are antioxidants?
The term antioxidant covers a wide range of molecules - atoms linked by chemical bonds - that protect other molecules from a chemical process called oxidation.
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That's fine, because oxidation can damage vital molecules in our cells, including DNA and proteins, which are responsible for many bodily processes. In fact, molecules, such as DNA, are necessary for the proper functioning of cells; So, if too many are damaged, the cell may malfunction or die. Antioxidants can prevent or reduce this damage.
In our body, the oxidation process usually occurs because of other types of molecules that are highly reactive: free radicals.
Not all oxidation is bad
Oxidation is a common chemical reaction in which electrons are transferred from one molecule to another. And electrons are one of the subatomic particles - smaller than an atom - that make up practically everything. As the electrons move during an oxidation reaction, their bonds can break and the structure of the molecules changes.
Not all oxidation reactions are bad. Some are essential for life and are involved in many other important processes. In cellular respiration , for example, glucose is oxidized by oxygen, producing carbon dioxide, water and energy to nourish our body. And, in another area, domestic bleach act by oxidizing color stains in colorless molecules.
Other less desirable oxidation reactions are metals and food spoilage.
And, free radicals?
Free radicals are simply molecules with one or more odd electrons. Electrons like to be in pairs, so odd electrons can result in unstable and highly reactive molecules.
To stabilize, the free radical must steal an electron from another molecule (or give one). When a molecule loses an electron, it oxidizes and becomes a free radical. This new free radical can steal an electron from another molecule and start a chain reaction. This process permanently changes the structure of the molecules and triggers irreversible damage.
But if there is an antioxidant present, you can donate an electron to the free radical, stabilizing it and stopping the chain reaction. The antioxidant is sacrificed and oxidized in place of the other molecule, becoming a free radical. Unlike most molecules, the antioxidant is able to stabilize the unpaired electron and does not become highly reactive. This process deactivates the antioxidant.
Free radicals are not always bad for us. The immune system uses its highly reactive and destructive nature. Certain white blood cells, called phagocytes , can wrap foreign particles, such as bacteria, then seal them and release free radicals to destroy them.
Free radicals are naturally generated by our body, but can be multiplied by lifestyle factors such as stress, poor diet, pollution, smoking and alcohol. Our bodies can handle some free radicals, but forming too many can overwhelm the body's normal defenses.
It is believed that the damage of free radicals is one of the causes of aging and contributes to various diseases. For example, the damage of free radicals to DNA can cause genetic mutations and promote cancer.
So, antioxidants are good, right? It is not so simple
If free radicals are dangerous and cause aging and diseases, and antioxidants can neutralize them, then getting more antioxidants should be good, right? Unfortunately, it's not as simple as that. Yes, high antioxidant levels and low oxidative stress are associated with good health , but not all antioxidants are the same.
Antioxidants come from many sources. Some occur naturally in the body and some occur naturally in the food we eat. Antioxidants - natural or synthetic - can also be added to foods that do not normally contain them, either because of their (presumed) value for health or to preserve food (antioxidants also prevent oxidation in foods).
A healthy diet is the most effective way to get the antioxidants your body needs. Fruits, vegetables, grains, eggs and nuts are all useful sources of antioxidants. Despite the marketing exaggeration, the antioxidants found in so-called superfoods are no more effective than those of common fruits and vegetables, so it's better to save money.
But it's a different story when it comes to antioxidant supplements. Research has found that antioxidant supplements can cause more harm than good. A 2012 meta-analysis of more than 70 trials found that antioxidant supplements are ineffective or even detrimental to health. The reasons are not clear, but it is likely that the additional nutritional benefits derived from the consumption of antioxidants in a healthy diet contribute to this. In addition, high concentrations of antioxidants associated with the use of supplements can cause problems.
Too much of a good thing
There are a number of reasons why high concentrations of antioxidants can be harmful. In high concentrations, antioxidants can:
- - Act as pro-oxidants , increasing oxidation
- - Protect healthy cells, but also dangerous ones, such as cancer cells
- - Reduce the benefits of exercise for health
- - Having unwanted side effects, such as nausea and headaches , or even reaching toxic levels
There is no magic pill, although a healthy diet can provide all the antioxidants you need to fight the damage caused by free radicals.