- Antioxidants have been recognized as a critically important component of a healthy diet, credited with protecting the body against everything from age to cancer.
- In the normal course of metabolism, and in response to environmental stressors, destructive molecules called free radicals are formed that can wreak havoc on the body if left unchecked.
- There are many types of antioxidants—some produced by the body and some absorbed from foods—that work together to neutralize the free radicals and protect the cells from oxidative damage.
One of the tools which can help our immune system be as strong and resilient as possible, as well as avoid use of unnecessary pharmaceutical products, is our diet. Since the 1990s, foods “high in antioxidants” have been promoted as super foods that will do everything from keeping us young to preventing cancer. We are told that a diet rich in berries, kale, and dark chocolate will protect us from the ravages of time and a toxic environment, but exactly how does diet affect wellness? What exactly is an “antioxidant” and why is it important to the overall health of the human body?
It Starts With A Natural Process
Oxidation is the result of the body’s natural role in turning food into energy. Probably the most straightforward definition comes from the National Cancer Institute, which defines oxidation as, “A chemical process in which oxygen is used to make energy from carbohydrates (sugars).”1
The inevitable byproduct of this activity is a damaged metabolite called a “free radical,” referring in this case not to dissatisfied rebels who want to change the world but to molecules that circulate freely throughout the body despite having an unpaired electron.2 In the normal course of things, a working molecule that loses an electron (or more) becomes an unstable and highly reactive, “oxidized” metabolite that attacks other molecules to replace its missing parts—and can wreak havoc on the body’s systems if not kept in check.
Molecules subsequently robbed of an electron then become free radicals themselves. Joseph Mercola, DO explains:
Free radicals steal electrons from the proteins in your body, which badly damages your DNA and other cell structures. They can create a ‘snowballing effect’—as molecules steal from one another, each one becomes a new free radical, leaving a trail of biological carnage.3
In addition to the natural rhythms of metabolism, the body also produces free radicals in response to environmental stressors like cigarette smoke, chemicals, pollutants, or pharmaceutical products; in response to sunlight; during exercise; and whenever there is inflammation present in the body for any reason.2
According to Harvard University’s T. H. Chan School of Public Health:
Free radicals come in many shapes, sizes, and chemical configurations. What they all share is a voracious appetite for electrons, stealing them from any nearby substances that will yield them.4
Free Radicals Are Not All Bad
It is important to note that free radicals are not pure villains but do have important roles to play. They act as biologic signaling molecules in regulating the flow of blood through the heart in stressful situations, although chronically high levels of free radicals are thought to contribute to heart failure.5 Free radicals also have therapeutic and protective effects against many diseases and help regulate the effects of exercise.6
It is when the number of free radicals gets unbalanced that their destructive effects on the body are exhibited as “oxidative stress.”
Antioxidants to the Rescue
Antioxidants are the body’s answer to controlling the population of free radicals. There are many types of antioxidants and, while they have different roles and characteristics, they all share the ability to sacrifice their own electrons to complete a free radical without turning into free radicals themselves.3
When faced with an overabundance of free radicals, the antioxidants may act in one of several ways to neutralize them and inhibit the cell damage they are causing.
The way they behave depends on what type of antioxidant is in play. Some are preventive, helping to counter the formation of the free radicals in the first place. Others act to scavenge for the free radicals and disrupt the process that leads to cell damage. Still others repair and “clean up” the oxidized proteins, to keep them from accumulating. The final step in this defensive system is “adaptation,” which involves creating the right antioxidant for the job and getting it to wherever it’s needed.2
There Are Important Differences Among the Antioxidants
Antioxidants can be categorized in several ways. They can be either water-soluble or lipid(fat)-soluble.7 The water-soluble types (such as vitamin C, polyphenols, and glutathione) act on the water-based fluids both inside and outside of the cell, and the fat-soluble antioxidants (such as vitamins A and E, carotenoids, and lipoic acid) act on the lipid-rich cell membranes.
They can also be characterized by size. Large-molecule antioxidants are primarily produced by the body and absorb the destructive reactive oxygen species (ROS), while smaller-molecule antioxidants usually come from food and form the “cleanup crew” that neutralizes the ROS.3
Third, antioxidants can be sorted by whether they are enzymatic (made by the body) or nutrient based (food sourced). The most important of those metabolically produced seem to be glutathione, ubiquinol, and uric acid. The diet provides a wide variety of antioxidants. Most attention is given to vitamin E (α-tocopherol), vitamin C (ascorbic acid), and B-carotene, but that is just the start of the list. Enzymatic and nutrient antioxidants do not perform in a vacuum though, but work together. Those produced by the body, for example, need help from the diet because they require trace elements like selenium, manganese, copper and zinc to function properly.8
Finally, antioxidants can be categorized by their ORAC (oxygen radical absorbance capacity) value, a system used to define the neutralization power of a given antioxidant.9
How Diet Can Help
The myriad types and specific functions of antioxidants found in foods will be addressed in a follow-up to this article. For starters, medical professionals agree that it is vital to include a wide variety of unprocessed foods in the diet, because each of the food groups provides unique and necessary antioxidants and some provide more than others.
Nutrition gurus and the general medical community alike agree that one of the most useful tips for shoring up our all-important antioxidant intake is to “eat the rainbow.” Not counting neon food coloring, the rainbow should include a mix of blue/purple/red foods (grapes, berries, beets, eggplant), orange/yellow (sweet potatoes, carrots, oranges, peppers, cantaloupe), green/dark green (spinach, kale, broccoli), and even some white (sprouts, cauliflower). Nuts, seeds, and beans are also given thumbs up all around.
Though clinical trials of supplementing the diet with antioxidants to offset existing disease have been mostly inconclusive, there is evidence that “eating whole fruits, vegetables, and whole grains—all rich in networks of antioxidants and their helper molecules—provides protection against illness and the effects of aging.”4
1 NCI Dictionary of Cancer Terms. U.S. Dept. of Health and Human Services.
2 Lobo V et al. Free Radicals, Antioxidants And Functional Foods: Impact On Human Health. Pharmacognosy Review July-December 2010.
3 Mercola J. The Ultimate Guide to Antioxidants. Mercola.com c 2016.
4 Antioxidants: Beyond the Hype. Harvard T. H. Chan School of Public Health.
5 Karolinska Institutet. Free Radicals May Be Good For You. Science Daily Mar. 1, 2011.
6 Pham-Huy LA et al. Free Radicals, Antioxidants in Disease and Health. Int J. Biomed Sci June 2008.
7 Arnarson A. Antioxidants Explained in Human Terms. Authority Nutrition. C. 2016.
8 Beyond the ORAC Score: Why a Variety of Antioxidants Is Important. SuperFoodly April 3, 2013.
9 Haytowitz DB, Bhagwat S. USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2. U.S. Department of Agriculture May 2010.