Antioxidants – Part 1

You may have heard a lot about antioxidants, or seen them advertised on various food products. You have probably heard that antioxidants protect your body by mopping up free radicals. Perhaps you even know of some foods that are good sources. But do you know how antioxidants actually work? Nutritional terms often get tossed around without much thought.  Understanding a bit more about how things work will give us a greater appreciation for the “good” antioxidants do for our bodies.

Free Radicals and Oxidation

Free radicals are the compounds that antioxidants combat. Essentially, free radicals are molecules with an odd number of electrons. Having an odd number is a bigger problem than it may seem. Electrons naturally pair into groups of two, thus the odd electron is missing its partner (and is unstable). This sets the unstable atom or molecule on a hunt for another electron, which it can steal from another atom or molecule and use to complete its pair. The electron is now used to stabilize the free radical, but the atom from which the electron is taken turns into a free radical itself and is affected in a variety of ways depending on what it is. This process is commonly called “oxidation” because free radicals usually contain an oxygen atom with a missing electron.

Whether you know it or not, you witness oxidation all the time. When cut apples turn brown, silver tarnishes, or metal rusts, you are seeing the effects of oxidation. Essentially, oxidation is the interaction between oxygen molecules and the substances they come in contact with.

Free Radicals in our Bodies

The problem facing humankind in particular, is that when atoms go hunting for an electron in order to become complete they may obtain it from our bodies. This often sets off a chain reaction where one atom after another steals an electron from its neighbor. This process can have serious consequences for the structures in the body. Free radicals can damage lipids in cell membranes, molecules of DNA, or the proteins that perform specific tasks within cells.[1] The physiological damage caused by free radicals can potentially include life-threatening problems that range from heart disease to diabetes or even cancer.[2]

So how do we end up with these dangerous free radicals in our bodies? Actually, many are formed when we digest our food. The digestion process breaks the molecular bonds in food, which often leaves molecules with an incomplete electron pair (a free radical). Other sources of free radicals include consumption of drugs, contact with pesticides, pollution, or cigarette smoking. While some of these factors may be avoidable, most free radicals are just a fact of life. We cannot simply stop eating and therefore avoid all pollutants. However, there is a way to stop the damage rampaging free radicals cause.

Free Radical Fighters

Antioxidants are nature’s answer to free radicals. Breaking down the word “antioxidant” lends us a clear description of their job: “anti” means against, and “oxidants” refers to the oxidation process free radicals cause. Chemically, antioxidants have the ability to donate an electron to a free radical while remaining stable. This electron donation effectively neutralizes the free radical.

For now, think of it this way: Cut apples oxidize and turn brown after being exposed to air for a short time. A common way to prevent this is dipping the apple slices in lemon juice. The vitamin C in lemon juice is an antioxidant and can prevent the apple from turning brown. In the same way, our body uses antioxidants to keep itself from deteriorating due to oxidation.[3]

Antioxidants are naturally occurring in many common foods. Many fruits, vegetables and grains contain these very important oxidation fighters. Antioxidants are especially prevalent in both vitamin C and vitamin E. Antioxidants are also readily available in the mineral selenium, in flavonoids, and in beta-carotene. In our next article, will be looking at each of these antioxidant sources in detail.

Eating a variety of antioxidant rich foods will protect the body from the harmful effects of oxidation. A good tip is to consume a colorful diet, full of different fruits and vegetables. This will not only ensure a large amount of antioxidants, but it will provide you with an excellent blend of other important nutrients. So be sure to eat your fill of antioxidants today.

In our next article, we will look at five common antioxidants and their common dietary sources.


[1] Sizer, Frances. Nutrition: Concepts and Controversies. Tenth edition. 2006. Thomson Higher Education. Belmont, CA.

[2] Antioxidants. (2011).  American Dietetic Association.

[3] Ibid.

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