What Are Antioxidants?

what are antioxidantsEveryone seems to be hyping up antioxidants these days. But if you ask the average Joe, “exactly what are antioxidants,” chances are you’ll get a blank stare in return.

Food manufacturers and dietary supplement companies make bold claims about the power of antioxidants, and they sell a lot of products by doing so.

In this article, I’ll help dispel some myths about antioxidants, explain what they are, and show you what foods are high in antioxidants.

What are antioxidants?

Antioxidants are substances that may help protect your cells from damage caused by free radicals, which are molecules that attack healthy cells. When healthy cells in your body are damaged by these free radicals, they’re more susceptible to cardiovascular disease, certain types of cancers, inflammation, and other conditions.

Types of antioxidants

Type Found in These Foods
Betacarotene sweet potatoes, carrots, cantaloupe, squash, apricots, pumpkin, mangos, green leafy vegetables like collard greens, spinach, and kale
Lutein green, leafy vegetables like Swiss chard, spinach, kale.
Lycopene tomatoes, watermelon, guava, papaya, apricots, grapefruit
Vitamin A liver, sweet potatoes, carrots, milk, egg yolks, and mozzarella cheese.
Vitamin C most fruits and vegetables, cereals, beef, poultry, and fish
Vitamin E almonds, wheat germ, safflower oil, corn oil, mangos, nuts, broccoli
Glutathione avocado, asparagus, broccoli, garlic, tomatoes
Coenzyme Q10 beef, chicken, pork, broccoli, nuts, seeds, oils
Lipoic acid broccoli, liver, beef, yeast
Flavonoids berries, nuts, beans, peppers, tomatoes, eggplant

Health benefits

Food companies are quick to tout the miraculous health benefits of antioxidants. But remember, they’re trying to sell you products, so they’re not the most objective source of information. Here’s what the research shows about the effect antioxidants have on certain health conditions.


According to the American Cancer Society, there’s “considerable laboratory evidence that antioxidants may slow or possibly prevent the development of cancer.” However, data from recent clinical trials is less clear. Several large-scale clinical trials showed inconsistent conclusions about the effect antioxidants have on cancer.[1]

Heart disease

In the Women’s Health Study, nearly 40,000 healthy women took vitamin E or a placebo every other day for 10 years. At the end of the study, heart disease (and cancer) rates were similar between the two groups, meaning vitamin E does not appear to help prevent heart disease.[2]

In the Women’s Antioxidant Cardiovascular Study, several antioxidants (vitamin E, vitamin C, and beta-carotene) did not help decrease risk of myocardial infarction, stroke, coronary revascularization, or cardiovascular death.[3]


The Physicians’ Health Study found that taking the antioxidant beta-carotene may help moderately reduce cognitive decline.[4]

Eye Health

The Age-Related Eye Disease Study found that taking a combination of vitamin C, vitamin E, beta-carotene, and zinc may help protect you against advanced age-related macular degeneration if you’re at high risk for this disease (but not cataracts).[5] Lutein, a naturally occurring carotenoid found in green, leafy vegetables such as spinach and kale, may also work to protect your vision.

Parkinson’s Disease

According to a 2012 study, a new and powerful class of antioxidants called synthetic triterpenoids could one day be a potent treatment for Parkinson’s disease. In animal model studies, these antioxidants blocked development of Parkinson’s disease.[6] However, more research is needed on this one.

Bottom line

It’s clear that free radicals contribute to chronic diseases like cancer and heart disease. It’s less clear though exactly what effect antioxidants have on helping prevent and/or alleviate these conditions. Most studies to date have been inconclusive.

So here’s my advice:

1. Forget the dietary supplements.

2. Eat more whole, natural, unprocessed foods like vegetables, fruits, nuts, and seeds. You’ll get all the antioxidants you need.

Want More?

This article is #6 in my 10-part Healthy Eating 201 tutorial.

To go to the next article and learn about the best healthy foods for kids click here.

To read article #5 about the best and worst types of fish for your health click here.

[1] http://www.cancer.gov/cancertopics/factsheet/prevention/antioxidants

[2] Lee IM, Cook NR, Gaziano JM, et al. Vitamin E in the primary prevention of cardiovascular disease and cancer: the Women’s Health Study: a randomized controlled trial. JAMA. 2005; 294:56–65.

[3] Cook NR, Albert CM, Gaziano JM, et al. A randomized factorial trial of vitamins C and E and beta-carotene in the secondary prevention of cardiovascular events in women: results from the Women’s Antioxidant Cardiovascular Study. Arch Intern Med. 2007; 167:1610–18.

[4] Grodstein F, Kang JH, Glynn RJ, Cook NR, Gaziano JM. A randomized trial of beta-carotene supplementation and cognitive function in men: the Physicians’ Health Study II. Arch Intern Med. 2007; 167:2184–90.

[5] A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta-carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. 8. Arch Ophthalmol. 2001; 119:1417-36.

[6] Georgia Health Sciences University (2012, July 23). Powerful class of antioxidants may be potent Parkinson’s treatment. ScienceDaily. Retrieved November 1, 2012, from http://www.sciencedaily.com­ /releases/2012/07/120723134755.htm