What Do Antioxidants Actually Do?

what do antioxidants doAntioxidants serve as a powerful first line of defense against damage to your cells from aging, stress, and inflammation. Moreover, antioxidants appear to contain cancer-fighting properties and to support the immune system (among many other benefits).

Many, many foods, especially colorful vegetables, contain a range of valuable antioxidants. We’ve listed a few of the most potent and popular choices for each class of antioxidants. Here, we’ll go through the most important ones.

What Do Antioxidants Do?

Antioxidants are molecules that capture free radicals, or harmful oxygen atoms, that occur in response to normal body processes and environmental conditions. Even the simple act of digesting your food produces free radicals.

Over time, an overabundance of free radicals can slowly damage healthy cells, and then healthy tissues and eventually organs. You want to minimize the damage as much as possible, and antioxidants can help protect you.

Your body can make some antioxidants, and you get others from food.

Antioxidants can be broken into two general categories: antioxidant enzymes, and antioxidant nutrients, which include vitamins, minerals and the various -noids detailed below.

Antioxidant Vitamins

Antioxidant vitamins can be broken down into flavonoids and carotenoids.


Flavonoids (also called bioflavonoids) are polyphenol pigment compounds that are present in most flowering plants. They are commonly grouped under anthocyanidins, proanthocyanins, and phenolics. The coolest fact about flavonoid antioxidants: they offer a double-punch because they improve vitamin C’s antioxidant capabilities.

Foods that contain flavonoids include tea, citrus fruit, citrus fruit juices, berries, red wine, apples, and others.1


Carotenoids are fat-soluble vitamins. (Beta carotene is the most studied, but there are 600+ carotenoids we know about so far. Other popular ones include lutein, zeaxanthin and lycopene.)

A lot of sources will say that one particular carotenoid, beta carotene, is the same thing as vitamin A, which isn’t exactly true. A percentage of beta carotene converts to vitamin A in the body, but not all of it. It’s best to get vitamin A from foods like liver, salmon, and others.

Foods high in carotenoids include apricots, beef liver, beets, broccoli, cantaloupe, carrots, guava, mangoes, salmon, and others. Fruits and vegetables that are orange, red, and yellow tend to be sources of carotenoids2

Antioxidant Enzymes

The antioxidant enzymes are superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx).

SOD: Cruciferous vegetables are a must!

CAT: Get enough iron from beef, mushrooms and sturdy greens to ensure proper catalase production.

GPx: Selenium activates this enzyme, so get plenty of eggs, chicken, and fresh garlic in your diet. If you’d like to supplement glutathione, you can take n-acetylcysteine, or NAC, a building block of glutathione that gives your body what it needs to make more.

Super Food List: The Best Antioxidant Foods by ORAC Value

Foods’ antioxidant quality is measured as an ORAC value, which stands for Oxygen Radical Absobance Capacity. Here is a list of some of the best antioxidant foods with the the highest ORAC values according to the USDA:

  • Prunes: 5770
  • Raisins: 2830
  • Blueberries: 2400
  • Blackberries: 2036
  • Kale: 1770
  • Strawberries: 1540
  • Spinach: 1260
  • Raspberries: 1220
  • Brussels sprouts: 980
  • Plums: 949
  • Alfalfa sprouts: 930
  • Broccoli flowers: 890
  • Beets: 840
  • Oranges: 750
  • Red grapes: 739
  • Red bell pepper: 710
  • Cherries: 670
  • Kiwi fruit: 602
  • Grapefruit, pink: 483
  • Onion: 450
  • Corn: 400*
  • Eggplant: 390

*Corn is a grain, which may not work for people following a Primal lifestyle.

These lists of antioxidants and antioxidant foods are certainly not comprehensive, as there are thousands of phytonutrients currently being studied and more are discovered every year. Bottom line: the more you get, the better. A combination of prudent supplementation and plentiful, colorful vegetables is your smartest bet.

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25 thoughts on “What Do Antioxidants Actually Do?”

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  1. PS – Though I left it out of the post (too many to cover) I recommend ensuring you get plenty of CoQ10 as well. I personally take the Master Formula as it has the most potent, comprehensive antioxidant profile for the value.

  2. Interesting article here


    about a study that showed flavonoids are not directly antioxidant, but are still beneficial through a different mecahnism:

    “If you measure the activity of flavonoids in a test tube, they are indeed strong antioxidants,” Frei said. “Based on laboratory tests of their ability to scavenge free radicals, it appears they have 3-5 times more antioxidant capacity than vitamins C or E. But with flavonoids in particular, what goes on in a test tube is not what’s happening in the human body.”

  3. From Mark’s excellent argument against raw foodism:
    “Fact: You cannot be deficient in enzymes (unless you have a rare genetic condition). You don’t need enzymes from food. Your body has its own digestive enzymes or builds specific enzymes within cells to catalyze biochemical reactions. No amount of living or dead food is going to change that. Don’t fall for enzyme therapy, “curative” enzyme supplements (unless they are digestive enzymes), and diets that focus on enzymes. Some of those juicer infomercials focus on “enzyme benefits” and they drive me nuts (I’ve ranted about this, of course).”

    I’m confused here. It seems that Mark is arguing that enzymes don’t have a nutritive benefit. To me, the enzymes they speak of in juicer infomercials would be antioxidant enzymes – ones derived from juicing vegetables. Without getting into why you shouldn’t juice and rather just eat the vegetable, and following the rest of his argument, shouldn’t the exception he makes for enzyme supplements be for antioxidant enzymes rather than digestve ones?

  4. Chris,

    Wow. Good stuff. Sometimes we are so close to this we forget how confusing it can be. CoQ10 is a “co-enzyme”. It is vital to human functioning. In fact, it probably should have been given “vitamin” status when they were naming all the vitamins. Many vitamins (and CoQ10)are considered co-enzymes in that they are involved in the operations or manufacturing of actual enzymes (but they are NOT enzymes themselves). Co-enzymes are co-factors upon which some of the larger, more complex enzymes depend to accomplish their tasks. Those larger enzymes are the ones I suggest you can’t consume in food and hope that they will have an affect on your health, because the acid in your stomach will break them down before they reach the bloodstream.

  5. Mark and team:

    I’m curious about glutathione . . . I read Art de Vany’s blog and he talks about taking a glutathione supplement along with your Damage Control. I’m using DC now. Any plans to include glutathione in it? Or should I add on an additional glutathione supplement?



  6. Why does the Wiki Say this:

    “…there is evidence that some types of vegetables, and fruits in general, protect against a number of cancers.[133] These observations suggested the idea that antioxidants might help prevent these conditions. However, this hypothesis has now been tested in many clinical trials and does not seem to be true, since antioxidant supplements have no clear effect on the risk of chronic diseases such as cancer and heart disease.”

    While everyone agrees that eating these foods can prevent “Cancers” its just the whole “free radical / antioxidant” connection to specific health gains, etc is on shakey ground.

    When I have these discussion with friends they always tell me I am more prone to gamma rays than having free radicals in my body. Comments?

  7. Oh my goodness! a tremendous article dude. Thank you However I am experiencing challenge with ur rss . Don’t know why Unable to subscribe to it. Is there anybody getting equivalent rss problem? Anyone who knows kindly respond. Thnkx

  8. I’m confused. Especially by the ‘more is better’ comment. I thought the research on antioxidants was far more complex than this. And that some research has shown that they can have a deleterious effect and that they have almost no beneficial effect on things like cancer incidence.

    1. This article is 13 years old. ORAC was withdrawn from credible circles back nearly a decade ago at this point. This site has been churning up old articles for a while now.