Plus, the best sources of these healthy compounds.
“Antioxidants” is one of those buzzwords that gets thrown around a lot. We know that foods full of these seemingly magical compounds are good for us—but what are antioxidants exactly? What do they actually do in our bodies? And why is everyone always singing their praises? Here’s what you need to know about the science behind what antioxidants can do for us.
What antioxidants are and what they actually do
Before we talk about antioxidants, we gotta talk about free radicals—another nebulous buzzword. "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.
Some free radicals are okay—these unstable molecules are actually naturally formed when we exercise and metabolize food, Dr. Giovannucci says. We can also be exposed to sources of free radicals in the environment, like cigarette smoke, sunlight, and air pollution, according to the National Center for Complementary and Integrative Health (NCCIH), a branch of the National Institutes of Health. Other environmental toxins that can cause high levels of free radicals are ionizing radiation and some metals, according to the National Cancer Institute (NCI).
But high concentrations of free radicals in the body can lead to oxidative stress, a process that can cause damage to your cells. That 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 NCCIH.
That’s where antioxidants come in. Known as free radical scavengers, according to the NCI, antioxidants effectively neutralize the free radicals that cause this oxidative stress (the anti in antioxidant). While we make some of our own antioxidants, our bodies count on our diets to get enough of them. “Antioxidants are compounds found in food that stop or delay damage to the cells,” Lauri Wright, Ph.D., R.D., L.D., assistant professor of nutrition at the University of South Florida, tells SELF.
Plant foods like fruits and vegetables are especially rich sources of these free-radical-crushing compounds, which include vitamin A, vitamin C, vitamin E, the mineral selenium, lutein, and lycopene, Wright says. “Antioxidants are released from the foods we eat through digestion and travel through the bloodstream and into cells,” where they do work on free radicals, Wright explains.
What we don't know about antioxidants
It's really hard to tell how important each individual antioxidant compound is in the human body. For one thing, there are just so many. As Dr. Giovannucci points out, there are many other lesser-known compounds in foods that, at least in laboratory settings, have been shown to have antioxidant properties. We’re talking thousands of antioxidative compounds, potentially. So it’s very possible that different antioxidants contained in, say, a tomato, are working together. “There are so many compounds that many interactions are possible,” Dr. Giovannucci says. Not to mention the many other vitamins, minerals, and phytochemicals present in plants!
Making things more complicated is the fact that it’s tricky to figure out how exactly these compounds act in the human body. Lab experiments demonstrate that antioxidants can counteract oxidative stress in cells and animals by stabilizing free radicals and preventing cell damage associated with developing cancer, the NCI explains. But a laboratory test can't tell us how something acts once it's in our digestive system and bloodstream. “In the body it has to first be absorbed in the intestine, then get to the appropriate organ in high enough concentrations, and then get to the precise part of the cell that experiences free radical damage,” Dr. Giovannucci explains. This all makes it pretty hard to pinpoint the role of any one antioxidant in our health.
What experts can do is observe how certain foods high in antioxidants are associated with reduced disease risk, and make recommendations as to what we should eat more of based on those associations, Dr. Giovannucci explains. “For some examples, tomatoes, which are high in a potent antioxidant, lycopene, appear to be associated with a lower risk of aggressive prostate cancer. Foods high in beta-carotene appear to be associated with a lower risk of breast cancer (particularly, estrogen receptor negative breast cancer), and coffee, which is high in many antioxidants, appears beneficial for some liver diseases including liver cancer,” he says.
Why you should load up on antioxidant-rich foods instead of supplements
Experts like Wright and Dr. Giovannucci generally suggest getting antioxidants from whole foods instead of supplements for a few good reasons. Like we talked about, studies can’t really tell us if it’s certain antioxidants specifically or other components of these plant foods that are responsible for the positive health benefits they're linked with—or some synergistic combination. So by eating a variety of whole food sources, you get all the benefits linked to all these different nutrients, regardless of the particular roles they may play.
The whole food packages that high concentrations of antioxidants come in are all-around really, really good for you. First of all, the vitamins and minerals that have antioxidant properties are also essential nutrients, Dr. Giovannucci explains, meaning that we need them for various aspects of our health. And foods high in antioxidants, like fruits and veggies, pack in a ton of other good stuff your body needs—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. Wright suggests aiming for a colorful variety. And don’t worry yourself with getting a certain amount of a certain type, or even learning the names of different antioxidants. Just know, “a good diet should contain a broad spectrum of plant foods,” Dr. Giovannucci says. As the NCCIH notes, there is good evidence that eating plenty of fruits and veggies is healthy, and decades of research to suggest that a diet full of these foods may help prevent diseases. There are also no safety risks that we should be worried about from eating these foods.
The exact opposite can be said of the research on antioxidant supplements: There is not good evidence that they are healthy for us, and they are associated with potential safety risks. 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, the NCI says. (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.)
What's more, 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. Antioxidant supplements can also interact with certain medications, the NCCIH points out. (For instance, the combination of vitamin E and anticoagulant drugs may increase the risk of bleeding.)
Antioxidant-rich foods to include in your diet
Not only are whole foods backed by better science than supplements—they’re much tastier too! And there are a lot of different options. In 2010, an international group of nutrition researchers studied the total antioxidant content of over 3,100 kinds of foods (as well as herbs, spices, traditional medicinal plants, and dietary supplements). Pulling from the database they published in Nutrition Journal, here are some foods high in antioxidants—along with a variety of other nutrients and yumminess.
1. Coffee and tea
Caffeine lovers, you’re welcome. Coffee, black tea, and green tea are all great sources of antioxidants (although the levels in coffee varied widely across products and manufacturers, the Nutrition Journal study notes). One more reason to drink up!
These sweet, juicy gems—cranberries, blackberries, strawberries, raspberries, blueberries, goji berries—are bursting with antioxidants, sweetness, and fiber. Enjoy them fresh, frozen, dried, freeze-dried, or in jam form.
The antioxidant lycopene is responsible for the beautiful red color of tomatoes. The Nutrition Journal study found that tomato sauces and sun-dried tomatoes were more antioxidant-rich than the fresh ones, noting that heat processing makes the lycopene more bio-available.
4. Nuts and seeds
Nuts and seeds like walnuts, pecans, sunflower seeds, peanuts, hazelnuts, pistachios, and almonds were found to be particularly rich in antioxidants. Enjoy these crunchy little guys raw or roasted as a topping for your oatmeal or salad.
5. Dark chocolate
The good stuff is packed with a type of antioxidants called flavonoids, which comes from the cocoa it’s made with. The Nutrition Journal researchers found that the greater the cocoa content the greater the mean antioxidant content of the chocolate.
6. Spices and dried herbs
We usually think of spices and herbs as a way to add tons of flavor and aroma to our meals, not antioxidants! But the Nutrition Journal study found that allspice, cinnamon, cloves, mint, oregano, rosemary, saffron, sage, nutmeg, ginger, dill, and more had considerable antioxidant content.
7. Stone fruits
Full of naturally occurring sugars, fiber, and vitamins, fresh and dried apricots, pears, nectarines, and plums are wonderful for snacking, baking, trail-mixing, or chopping up for a salad or grain bowl topping.
8. Red wine
Red wine is rich in a type of antioxidants called polyphenols—resveratrol in particular, which comes from the skin of the grapes, the Mayo Clinic explains. (That’s why red wine, which requires a longer grape fermentation period, contains more resveratrol than white.)
9. Whole grain bread
Whole grains are a great source of fiber and antioxidants. The Nutrition Journal study found that among grain products, whole wheat breads and buckwheat, millet, and barley flours contained the most antioxidants.
Who saw artichokes coming? These unusual-looking, darn delicious plants are full of different antioxidants like vitamin C, hydroxycinnamic acids, and flavones—whatever the heck those even do.
This ruby-red fruit is packed with polyphenol antioxidants like tannins and flavonoids. The Nutrition Journal study found that both the whole arils and the juice made from them are great choices.
12. Curly kale
The notorious leafy green has a lot of fiber, vitamins, and antioxidants. It really shines when you know how to make a kale salad that actually tastes amazing.
Written by Amy Marturana Winderl, C.P.T. and Carolyn L. Todd
This originally appeared on Self US.