They say an antioxidant a day keeps the doctor away (or something along those lines). From sports drinks to candy bars, countless foods claim to be "packed with healthy antioxidants." So what are these nutrients and what do they really do?

Wait, What’s Oxidation Again? - The Need-To-Know

Antioxidants are nutrients that prevent or slow oxidative damage throughout the body. Without busting out the biochemistry books, when cells use oxygen, they naturally generate free radicals (by-products) which can cause cellular damage. Antioxidants act as free radical bounty hunters that prevent and repair damage done by the free radicals [1].

Oxidative damage can contribute to serious health problems such as heart disease (the nation’s #1 killer) [2], macular degeneration [3], diabetes [4], and cancer [5].

Think acai berries are the only way to go for a boost of antioxidants? Luckily, a healthy diet is packed with antioxidants that are relatively easy to stock up on, so grab a pen and paper and add these to the shopping list:

Vitamin E: Nuts, whole grains, vegetables, vegetable oil, liver oil, and elephant tears (not really).

Vitamin C: Any citrus fruit, tomatoes, green leafy veggies, and strawberries.

Vitamin A: Apricots, cantaloupe, squash, broccoli, sweet potatoes, carrots, kale, collards, and prunes.

Selenium: Brazil nuts, fish/shellfish, red meat, grains, eggs, garlic, and milk.

Flavonoids: Soy, red wine (winning!), pomegranate, cranberries, blueberries, tea (forget black and yellow, perhaps Wiz Khalifa should have been singing black and green since those seem to have the highest flavonoid levels.)

Lignan: Flax seed, barley, rye, and oats.

Lutein: Dark green fruits and vegetables such as kiwi, spinach, brussels sprouts, kale, and broccoli.

You: Antioxidant enzymes produced by the body include glutathione peroxidase, superoxide dismutase, and catalase [6]. (Don't misunderstand us and try to placing yourself in the shopping cart. If older than 5, this may result in being escorted out of the store, damaged limbs, or wheeeeeee the best ride ever! But probably the damaged limbs thing first.)

But this seems like an awful lot of food to add to a grocery list. Can’t one just pop a few vitamin E supplements and call it a day? As of right now, when it comes to the free-radical fighting benefits of supplements compared to natural food sources, the answer still remains up in the air.

One study shows an association between taking beta-carotene supplements with an increased risk of lung cancer in smokers (yikes!) [7]. But while the verdict isn’t quite out yet when it comes to supplements, eating antioxidants naturally through a healthy diet definitely gets a stamp of approval.

Time to Stock Up On Prunes (Maybe) — Your Action Plan

So grandma may be right on with her prune obsession - the dried fruit contains the highest amount of antioxidants per serving out of any other fruit or vegetable. Wow. Not a big fruit and veggie fan? Even though 70% of the above grocery list consists of fruits and vegetables, there are other options. In fact, Americans actually obtain more antioxidants from coffee than any other dietary source. Although it can't hurt to eat a few extra veggies, drastic dietary changes aren't needed to pack in some antioxidants and keep those free radicals at bay.  And if researchers ever discover that elephant tears do in fact contain large quantities of Vitamin E, good luck picking them up at the local supermarket!

Expert’s Take

Reva Rogers, Dietician: RD, MHA: “Always consider natural food sources of antioxidants before turning to supplements. Taking supplements sometimes make it dangerously easy to overdose on vitamins and minerals such as vitamin A. Acute doses of vitamin A greater than 200,000 micrograms are associated with nausea, vomiting, increased cerebrospinal pressure, blurred vision, and muscular discoordination.”

Updated August 2011