OK, But What Are Antioxidants Really?

You've likely heard that antioxidants are super good for you and that they can fight "free radicals." But do you actually know what they are and why their arch enemy poses a threat to our bodies?

Before we dive into how antioxidants protect us, first, we must break down the role of free radicals. Simply put, cell damage can occur as a result of exposure to free radicals, which can come in many forms — from the foods we eat to the byproducts of cell metabolism.

These harmful and unstable molecules are also present in environmental toxins, such as pollutants in the air, cigarette smoke and other volatile compounds.

So, free radicals cause oxidative stress on the cells they affect, potentially leading to systemic inflammation, as well as protein and DNA damage, according to June 2015 research in the ​European Journal of Medicinal Chemistry​.

And the end result spells out bad news for our overall health: Systemic inflammation and oxidative stress have been associated with an increased risk of various health issues including heart disease, cancer, diabetes and neurodegeneration, per the June 2015 study.

Antioxidants help protect our bodies from the cell damage free radicals pose. Here's how: Just as their name implies, antioxidants fight oxidation, which is a normal bodily process that can produce free radicals.

Free radicals contain an unpaired electron, and antioxidants neutralize and block free radicals by donating an electron of their own, Mariana Dineen, RD, founder and dietitian at Pretty Nutritious, tells LIVESTRONG.com.

"This generous donation deems free radicals harmless and prevents oxidative damage." Because antioxidants counteract the damage done by free radicals they can, in turn, reduce oxidative stress and systemic inflammation within the body.

Here are some of the more commonly known antioxidants, according to Australia's Department of Health and Human Services:

• ​Vitamin A and beta-carotene​: Found in yellow and orange-pigmented fruits and vegetables such as carrots, sweet potatoes, red and yellow peppers, cantaloupe, papaya and apricots. Spinach, broccoli and kale — although green — are also great sources of vitamin A; as are fish, eggs and beef liver.
• ​Vitamin C​: Found in citrus fruits, berries, Brussels sprouts, cauliflower, leafy greens, tomatoes and winter squash.
• ​Vitamin E​: Found in leafy greens, vegetable oils, sunflower seeds, almonds, hazelnuts and peanuts.
• ​Selenium:​ Found in seafood, lean meats, fortified cereal and milk products and Brazil nuts.
• ​Zinc​: Found in seafood, milk, nuts and meat.
• ​Copper​: Found in seafood, milk, nuts and meat.
• ​Manganese​: Found in seafood, lean meat, milk and nuts.

Other antioxidants include:

• ​Allium sulfur compounds​: Found in leeks, onions and garlic.
• ​Anthocyanins​: Found in red and purple produce such as eggplant, grapes and berries.
• ​Catechins​: Found in tea and red wine.
• ​Carotenoids​: Plant pigments found in yellow, red and orange produce. Types of carotenoids include lutein, zeaxanthin, lycopene and cryptoxanthins.
• ​Flavonoids​: A class of plant pigments found in tea, citrus fruits, red wine, onion and apples.
• ​Indoles​: Found in cruciferous vegetables such as broccoli and cauliflower.
• ​Isoflavonoids​: Found in soybeans, tofu, lentils, peas and milk. Their derivatives are known as phytoestrogens.
• ​Zoochemicals​: Found in animal products like red meat, eggs and fish. They're also derived from the plants that animals eat.

Deep-colored fruits and vegetables — such as berries, apples, plums, tomatoes, carrots and broccoli — are packed with antioxidants that are linked to protecting cells against heart disease and certain cancers, according to Harvard T.H. Chan School of Public Health.

What's more, people who ate more foods with flavonols — which are found in the majority of fruits and vegetables — were observed to have a lower risk of developing Alzheimer's disease years later, per a January 2020 study in ​Neurology.​

Aim to eat the recommended 1.5 to 2 cups of fruits and 2 to 3 cups of vegetables per day. Start by adding berries to oatmeal or cereal at breakfast; topping a sandwich with sliced tomatoes and lettuce at lunch; enjoying a fresh plum as a snack; and tossing some carrots and broccoli into a stir-fry at dinner to achieve an antioxidant-rich day.

Green tea contains different types of antioxidants called catechins.

A February 2018 review in ​Molecules and Cells​ looked at the antioxidants in green tea — especially EGCG (epigallocatechin gallate) — and found that the antioxidant is linked to delaying the onset of cancer.

What's more, the polyphenols in green tea have been associated with killing cancerous cells and stopping them from growing, according to the University of Maryland Medical Center. Green tea is most beneficial when it's freshly brewed, as decaffeinated, instant and bottled teas generally have less antioxidants.

The darker the chocolate, the higher it is in antioxidants called flavonoids, which give it that dark color. Dark chocolate has been linked to reducing blood pressure, lowering cholesterol and lessening the risk for blood clots.

A June 2015 study in the journal ​Heart​ found that eating dark chocolate regularly is associated with a reduced risk of adverse heart disease outcomes. Try pairing fresh berries with dark chocolate for an antioxidant-powered snack that's a crowd-pleaser.

Compared to green grapes, red grapes contain more antioxidants, which are found in the skin of dark red and purple grapes used to make red wine, such as Cabernet.

Red wines contain resveratrol and a group of antioxidants called anthocyanins, which are linked to controlling blood pressure, reducing damage to blood vessels and protecting against heart disease, per August 2017 research in ​Food and Nutrition Research​.

The health benefits of alcohol follow a J-shaped curve, meaning the protective effects are only seen with moderate drinking, according to a May 2017 study in the ​Journal of Studies on Alcohol and Drugs.​

So, that's not an excuse to down the whole bottle. Women over the age of 21 should stick to no more than one glass a day while men over 21 shouldn't have more than two glasses, according to the Centers for Disease Control and Prevention. And if you don't drink, there's no need to start to reap the health benefits — simply snack on a bunch of dark red- or purple-skinned grapes instead!