There are tons of buzzwords in the nutrition world, and “antioxidants” is definitely one of them. But what are antioxidants really, and how do they affect your body?
From ketchup to pomegranate juice, plenty of foods are known for containing antioxidants. You’ve probably heard those compounds can do a lot for your health—they’ve been touted as doing everything from preventing heart disease to cancer—but are they as helpful as people say they are? What are these supposedly magical compounds, exactly, and why is everyone always making such a big deal out of them?
Like many things in the nutrition field, there’s a lot to unpack regarding antioxidants. And, despite marketing claims singing their praises, they’re not exactly a panacea on your dinner plate. That doesn’t mean you should discount them, though: Antioxidants can bring a bunch of benefits with them.
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 them into your diet.
What are antioxidants?
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, M.D., 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, Ph.D., associate dean for research at Texas Tech University Health Sciences, tells SELF. Some other environmental toxins, like 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 always necessarily bad on their own—and as natural byproducts of metabolic processes (like eating and exercising), some free radicals are OK. 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. Antioxidants 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 toneutralize free radicals and other molecules in your body that can damage cells and tissues, Mahdi Garelnabi, Ph.D., 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 your body 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, Ph.D., R.D., L.D., 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 “superfoods.” You can find antioxidants in a broad range of foods—like fruits, vegetables, seafood, whole grains, and meats—as well as in supplement form. (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 vitamin 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, Ph.D., 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).
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 food rather than specific antioxidants themselves—not to mention, other related lifestyle or dietary factors.
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. People who ate the most antioxidants had a 21 percent 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. 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.
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. And Dr. Giovannucci notes that high intake of lycopene (which tomatoes are rich in) appears to be associated with a lower risk of aggressive prostate cancer, while high intake of beta-carotene (found in carrots) 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 (or antioxidants in general) 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). 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 to get more antioxidants
Antioxidants in foods
Experts generally suggest getting antioxidants from whole foods instead of supplements for a few good reasons.
As we mentioned, studies can’t really tell us if it’s the antioxidants specifically or other components of an antioxidant-rich food (like other vitamins and minerals) that are responsible for the positive health benefits, or 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.
By eating a variety of whole food sources, you get all the benefits linked to all the different phytonutrients, regardless of the particular roles they may play.
Plus, the whole-food packages—berries, greens, root veggies, nuts, grains, coffee—are all-around really, really good for you. Antioxidant-rich foods like fruits and veggies pack in a ton of other good stuff your body needs, like other essential vitamins and minerals (that are not antioxidants), 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. For selenium, the RDA is 55 micrograms per day. For some nutrients, like zinc and vitamins A, C, and E, you can find RDAs for your age and sex in the Dietary Guidelines for Americans. (For instance, each day women 31-50 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, like 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 consume for the antioxidants that aren’t essential nutrients. (Researchers are still working on that, says Dr. Bolling.) You won’t see the dose of those antioxidants listed on the label of foods containing them, either.
So rather than trying to hit a specific amount of different types of antioxidants, focus on adding various foods that contain antioxidants 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,” says Dr. Bolling.
The best way to enrich your diet with antioxidants is to eat plenty of fruits and vegetables (the U.S. Dietary Guidelines recommend two and a half cups of vegetables and two cups of fruits per day), says Dr. Garelnabi. Nuts, whole grains, dark chocolate, and tea are also good antioxidant sources, as are lean meats and seafood, says Dr. Shen.
And again, diversity is also important in your diet, since some antioxidants work better together, says Dr. Garelnabi. Dr. Wright suggests aiming for a colorful variety. 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. For example, reddish foods like 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 like mangos, yellow peppers, oranges, bananas, and nectarines are good sources of vitamin C.
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, says Dr. Garelnabi.
While there is decades of good evidence that eating plenty of fruits and veggies is healthy, 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, 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.” 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 foods, there is some evidence that antioxidant supplements may even be harmful, especially in high doses. For example, some studies have linked high-doses of particular antioxidant supplements to increased risk of certain diseases (like 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 people take these supplements in the hopes 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 them and whether they could interact with any medications you take. Also keep in mind that because supplements are not regulated like pharmaceutical drugs, it can be hard to know exactly what you’re getting when you buy them.
Otherwise, if you’re focusing on a 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, says Dr. Garelnabi.
Additional reporting by Amy Marturana Winderl, C.P.T. and Carolyn L. Todd.