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What Are Antioxidants and How Much of Them Should You Be Eating?

They’re easier to take in than you may think.

June 18, 2022

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There are tons of buzzwords in the nutrition world, and antioxidants is definitely one of the more frequently used ones. But what are antioxidants, really? How do they actually affect your body? What food sources include them—and how much do you need to get?

From foods branded as superfoods (like the acai berries in your morning smoothies) to more humble sources (like the ketchup on your burger), plenty of foods contain antioxidants. Even if they all aren’t famous for it, thousands of different foods—especially plant-based foods—have some of these special compounds inside.

Now, you’ve probably already heard that antioxidants can do a lot for your health—they’ve been touted as potentially being able to do everything from helping to prevent heart disease to promoting glowing skin to boosting the immune system to even assisting in warding off cancer. But what do antioxidants do for real, and are they really as helpful as people say? What are these supposedly magical compounds, exactly, and why is everyone making such a big deal out of them?

As with many things in the nutrition field, there’s a heck of a lot to unpack regarding antioxidants. Antioxidants started to earn their status as a household name in the 1990s, when researchers began doing more and more studies about their potential benefits. In 1997, the U.S. Food and Drug Administration (FDA) issued its first guidance for how food and supplement companies could use the word antioxidant in association with nutritional claims on the labels of their products.

However, even to this day—25 years later—scientists’ understanding of these substances and their possible health effects is still evolving. And despite headlines, social media posts, and marketing claims singing the praises of antioxidant foods, drinks, and supplements, they’re not exactly a panacea on your dinner plate. (Or your cup, for that matter—sorry, but the antioxidant-rich pomegranate juice starring in your favorite summer cocktails is not a magic elixir.) But all this definitely doesn’t mean you should discount the importance of antioxidants in your diet, though: Antioxidant-rich foods can, in fact, offer benefits in support of your health and well-being.

Here’s what you need to know about the science behind how antioxidants work, what antioxidants can actually do for us, and how best to incorporate a variety of nutritious antioxidant foods into your diet.

What are antioxidants?

Antioxidants are a type of healthy compound, commonly found in foods like fruits and vegetables, that help defend the body against a process called oxidative stress, which is thought to be involved in the development of various diseases.

Okay, let’s unpack that a bit. Before talking about what an antioxidant is, it helps to understand what we mean by another wellness buzzword: free radical.

“Free radicals is a general term used for compounds that are highly reactive, which means that they can attach and bind to, and ultimately damage, normal [cells] in the body, such as DNA,” Edward Giovannucci, MD, professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health, tells SELF. To get a little more technical, free radicals are any molecules in your body that contain an unpaired electron, which makes them very unstable and keeps them looking for other compounds to bind to.

Your body generates free radicals during activities like digestion and vigorous exercise, as well as in response to things like UV light exposure, pollution, and smoking, Chwan-Li (Leslie) Shen, PhD, associate dean for research at Texas Tech University Health Sciences, tells SELF. Some other environmental toxins, such as ionizing radiation and certain metals, can cause abnormally high levels of free radicals to be produced in the body, according to the National Cancer Institute (NCI).

Free radicals aren’t necessarily bad on their own—and as natural byproducts of metabolic processes (like eating and exercising), some free radicals are okay. They can actually serve some important functions in the body, such as signaling between cells.

It’s when free radicals are produced in excess that they can become problematic. Because they are so reactive, free radicals can cause damage to cells through a process called oxidative stress. Oxidative stress is believed to be a factor in the development of a number of conditions such as cancer, heart disease, type 2 diabetes, Alzheimer’s disease, Parkinson’s disease, cataracts, and aging-related macular degeneration, according to the National Center for Complementary and Integrative Health (NCCIH) at the National Institutes of Health.

This is where antioxidants come in. And what do antioxidants do here? They can help keep these free radicals in check. Known as free radical scavengers, according to the NCI, antioxidants work against that oxidative stress (anti-oxidative) by helping to neutralize free radicals and other molecules in your body that can damage cells and tissues, Mahdi Garelnabi, PhD, an associate professor of biomedical and nutrition sciences at the University of Massachusetts-Lowell, tells SELF. (They do this through a variety of mechanisms, such as by lending an electron to a free radical to make it less reactive or by binding to a substance in a way that prevents further reactions.)

By stabilizing these free radicals, antioxidants can also help your immune system function more efficiently and mitigate chronic inflammation, which is thought to be a driving force for many health problems, like cardiovascular disease and cancer. Antioxidants may also, through separate mechanisms, help repair DNA and cell membranes.

Where can you find antioxidants?

Your body makes some antioxidants on its own, but sometimes that’s not enough. “A lot of times, your body generates too many free radicals, and it cannot handle it, so external antioxidant intake is important,” Dr. Shen says.

When we talk about getting antioxidants, we’re talking about “compounds found in food that stop or delay damage to the cells,” Lauri Wright, PhD, RD, LD, chair of the department of nutrition and dietetics at the University of North Florida, tells SELF. “Antioxidants are released from the foods we eat through digestion and travel through the bloodstream and into cells,” where they work on free radicals, Dr. Wright explains.

There are thousands of antioxidants, and they are not only present in highly hyped antioxidant foods or superfoods. You can find antioxidants in a broad range of foods—like fruits, vegetables, seafood, whole grains, and meats—as well as in a wide range of supplements, such as vitamins for immune system health, certain protein powders and meal replacements, and formulas with antioxidants for skin, just to name a few. (More on supplements later!)

Some antioxidants are essential vitamins that your body needs to function, while others are essential minerals. Examples of antioxidant vitamins include the immune-boosting vitamins C (found in brussels sprouts, red cabbage, and peppers), vitamin E (found in almonds, sunflower seeds, and olive oil), and vitamin A, which your body makes from beta carotene (found in collard greens, sweet potatoes, and cantaloupe). Examples of antioxidant minerals include selenium (found in Brazil nuts, pork, and turkey) and zinc (found in oysters, beef, and pumpkin seeds).

Then there are antioxidants that aren’t exactly considered essential nutrients but still have effects on cells and tissues, Bradley Bolling, PhD, an assistant professor of food science at the University of Wisconsin-Madison, tells SELF. You can find these in plant, animal, and other dietary sources.

A few examples of these antioxidants include carotenoid cousins of beta carotene, such as lycopene (found in watermelon, tomato sauce, and ketchup) and lutein and zeaxanthin (found in spinach, romaine lettuce, and Swiss chard), chlorogenic acid (found in coffee, apples, and eggplants), flavonoids (found in berries, tea, and citrus fruits), and ergothioneine (found in mushrooms, tempeh, oats, and kidney beans).

What are the health benefits of antioxidants?

As a whole, antioxidants can be helpful because they fight back against that oxidative stress, which is linked to the wide swath of health problems mentioned above.

Of course, it’s important to understand that a multitude of factors determines your risk of developing various diseases—oxidative stress is just one of them. Research does point to a broad range of health benefits in people who consume more antioxidants, but the NCCIH notes that it’s possible the benefits of antioxidant-rich diets may have to do with a combination of substances in the antioxidant-rich foods rather than specific antioxidants themselves—not to mention other related lifestyle or dietary factors.

So let’s take a closer look at some of the research showing a link between high antioxidant intake and reduced risk of disease.

In one study published in the European Journal of Nutrition, researchers classified 23,595 Americans into four groups based on their antioxidant consumption.¹ People who ate the most antioxidants had a 21% lower risk of dying over a 13-year period than people who ate the least, even as the researchers accounted for relevant mitigating factors such as participants’ age, sex, and economic status. (It’s worth noting, though, that this study was based on a 24-hour dietary recall, or people’s recollections of just one day of eating.)

Research also indicates that high amounts of dietary antioxidants may influence your risk of developing type 2 diabetes and stroke.^2,3 And according to a meta-analysis published in Critical Reviews in Oncology/Hematology of 19 previously published studies that included over 700,000 people, a diet high in antioxidants may reduce the risk of cancer, with significant reductions seen with colorectal, endometrial, and gastric in particular.⁴

There is even evidence to suggest that particular antioxidants are associated with lower risks of particular diseases, though it’s generally really hard to tease out specific relationships. Still, higher intake of flavonoids has long been linked with a reduced risk of heart disease, and a recent study in the American Journal of Clinical Nutrition suggests an association with a reduced risk of Alzheimer’s disease too.^5,6 And Dr. Giovannucci notes that high intake of lycopene appears to be associated with a lower risk of aggressive prostate cancer,⁷ while high intake of beta-carotene appears to be associated with a lower risk of breast cancer (particularly, estrogen receptor negative breast cancer).

It’s worth emphasizing that much of the research we’ve covered looked at total antioxidant intake, and what researchers found were correlations—not cause-and-effect relationships. While there’s plenty of research pointing to a link between higher antioxidant intake and lower risk of disease, we can’t say with certainty that loading up on certain antioxidants will change your health in specific ways. Dietary antioxidants are no substitute for medical care—and many factors contribute to the development of these diseases, some of which you can control, and some of which you can’t (like genetics). If you’re interested in what you can do to help lower your odds of a particular condition, it’s worth talking to your health care provider about your specific health history and risk factors—as well as the role that certain antioxidants may have on your health.

How do you get more antioxidants?

There are two main ways to get antioxidants: food and supplements. Experts generally suggest getting antioxidants from whole foods instead of dietary supplements for a few good reasons.

How to get enough antioxidants from foods

As we mentioned, studies can’t really tell us if it’s the antioxidants specifically or other components of antioxidant-rich foods (like other vitamins and minerals) that are responsible for the positive health benefits, or if it’s some synergistic combination. As Dr. Giovannucci points out, there are many lesser-known compounds in foods—potentially thousands—that, at least in laboratory settings, have been shown to have antioxidant properties, along with the many other phytochemicals present in plants. So it’s very possible that different antioxidants and other substances contained in, say, a tomato, are working together to nourish you.

By eating a variety of foods high in antioxidants, you get all the benefits linked to all the different phytonutrients, regardless of the particular roles they may play. Plus, these whole-food packages—like berries, greens, root veggies, nuts, whole grains, and coffee—are all-around really, really good for you. Antioxidant foods like fruits and veggies pack in a ton of other good stuff your body needs, like other essential vitamins and minerals, carbohydrates (including fiber and naturally occurring sugars), and water. In other words, there are many reasons to include an ample array of antioxidant-rich foods in your diet every day.

As for how much of these foods you should be eating to get enough antioxidants? For the antioxidants that fall into the essential-nutrient category, recommended daily allowances (RDAs) exist to help you plan your intake. With selenium, for example, the RDA is 55 micrograms per day. For some nutrients, like zinc and immune-boosting vitamins A, C, and E, you can find RDAs for your age and sex in the U.S. Dietary Guidelines for Americans. (For instance, each day women ages 31 to 50 should shoot for 8 milligrams of zinc, 700 micrograms of vitamin A, 15 milligrams of vitamin E, and 75 milligrams of vitamin C.) Some of these essential nutrients, such as vitamin C and vitamin A, are listed on food labels, so it’s easy to tally up how much you’re getting.

For the antioxidants that aren’t essential nutrients, there’s no standard recommended amount to take in each day. (Researchers are still working on that, Dr. Bolling says.) You won’t see the dose of those antioxidants listed on the label of foods containing them, either. And it’s not that simple to predict the exact amount of antioxidants present even in some foods high in antioxidants, as researchers explain in the Canadian Journal of Plant Science.⁸ The amounts can vary based on factors like growing conditions (plants produce phytochemicals as a natural defense against threats), and post-harvest storage and processing conditions. For example, some antioxidants, like carotenoids, degrade quickly when heated or stored for long periods of time; others, like flavonoids, are more stable.

So rather than trying to hit a specific amount, focus on adding various antioxidant-rich foods into your diet. For example, “just having berries for breakfast or eating citrus or drinking green tea is enough to put people into the higher level of patterns of consumption,” Dr. Bolling says.

The best way to enrich your diet with antioxidant foods is to eat plenty of fruits and vegetables (the Dietary Guidelines recommend two and a half cups of vegetables and two cups of fruits per day), Dr. Garelnabi says. Nuts, whole grains, dark chocolate, and tea are also good antioxidant sources, as are lean meats and seafood, Dr. Shen says.

And again, diversity is important in your diet, since some antioxidants work better together, Dr. Garelnabi says. Dr. Wright suggests aiming for a colorful variety of foods high in antioxidants. Trying to include different colors on your plate is a good idea, since the color of fruits and vegetables can serve as a clue to their antioxidant content, suggests a study published in Current Research in Food Science.⁹ For example, reddish foods such as apples, strawberries, sour cherries, red cabbage, and red peppers tend to be rich in a type of flavonoid called anthocyanins, while orange and yellow produce such as mangos, yellow peppers, oranges, bananas, and nectarines are good sources of vitamin C.

What to know about getting antioxidants from supplements

So what about supplements? Eating a balanced diet for most people means you’re likely getting enough antioxidants and don’t need to take antioxidant supplements, Dr. Garelnabi says.

While there are decades of good evidence that eating plenty of fruits and veggies is healthy,¹⁰ according to the NCCIH, the same can’t be said for antioxidant supplements. When it comes to preventing diseases, for instance, researchers have done a lot of studies on various antioxidant supplements, including large, robust clinical trials,¹¹ and most have found that antioxidant supplements do not reduce the risk of developing diseases like heart disease and cancer, according to the NCCIH. One 2014 review of the research stated “there is no evidence to support the use of antioxidant supplements in the primary prevention of chronic diseases or mortality.”¹² One theory on why supplements don’t appear to show health benefits is that the purified chemical versions of these antioxidants are too different from the complex combinations of compounds you get from consuming foods, the NCI explains.

Also unlike with antioxidant foods, there is some evidence that antioxidant supplements may even be harmful, especially in high doses.¹³ For example, some studies have linked high doses of particular antioxidant supplements to increased risk of certain diseases (such as beta-carotene and lung cancer, or vitamin E and prostate cancer), according to the NCI. While correlation doesn’t equate to causation, it’s enough to warrant concern, given that people often take these supplements in the hope of decreasing their risk of such diseases. Antioxidant supplements can also interact with certain medications, the NCCIH points out. (For instance, the combination of vitamin E and blood thinners may increase the risk of bleeding.)

If you’re considering taking a certain supplement, talk with your doctor first to determine whether you really need it and whether it could interact with any medications you take. Also keep in mind that because supplements are not regulated the way pharmaceutical drugs are, it can be hard to know exactly what you’re getting when you buy them.

Otherwise, if you’re focusing on variety in your diet and are making it a point to try new fruits or veggies to broaden what you’re taking in, you’re likely doing just fine on the antioxidant front.

And if you’re still interested in boosting your body’s supply of antioxidants, add that to the already long list of reasons to work out. Exercise—as long as you aren’t overtraining—may even help boost your body’s production of natural antioxidants, Dr. Garelnabi says.

Additional reporting by Amy Marturana Winderl, CPT, and Carolyn L. Todd.

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