What are antioxidants? And what do antioxidants do? Check out this guide to the best antioxidant-rich foods. It's not all berries and kale—good news for coffee and chocolate lovers!

Jessica Ball, M.S., R.D.
August 30, 2019

You've probably heard about antioxidants. But what exactly are they? And what do they do? So many foods, especially fruits and vegetables, tout antioxidant benefits. This article provides a definition for antioxidants and a list of antioxidant-rich foods based on the largest antioxidant database ever published.

What Are Antioxidants?

Beyond vitamins, minerals, protein and fiber (and all the other micro- and macronutrients), foods contain many other compounds that are important for our health. According to the National Institutes of Health, antioxidants are defined as naturally occurring or man-made substances that might prevent or delay oxidative damage to a cell. This is a category, meaning there isn't just one kind of antioxidant. Examples of types of antioxidants include flavonoids (like anthocyanin), carotenoids (like lycopene) and a lot of other compounds that are equally hard to pronounce and that may do the body good.

One way to measure total antioxidant content is with a test called the ferric-reducing ability of plasma assay, FRAP for short. This method quantifies all of the types of antioxidants present in a food. The measurement, expressed in millimoles (mmol) per 100 grams, enables easy comparison of the antioxidant capacity of different foods.

Related: Why You Should Eat the Rainbow When It Comes to Fruits and Vegetables

Health Benefits of Antioxidants

The benefit of antioxidants is spelled out in their name: they prevent oxidation. But what does this mean for us? First off, natural processes in the body are constantly creating unstable molecules called free radicals that can damage cells over time through a chemical reaction called oxidation. Additional sources of oxidative cell damage include environmental factors, such as air pollution, cigarette smoke and excessive sun exposure. Antioxidant substances can scavenge or mop up these free radicals. Oxidative stress, when there's not enough antioxidant activity in the body to counteract the free radicals, can cause damage to healthy cells and is implicated in diseases like cancer and cardiovascular disease.

In the lab and in animal studies, antioxidant substances have shown promise in protecting against many diseases and chronic conditions. But in people, as the NIH says, "Diets high in vegetables and fruits, which are good sources of antioxidants, have been found to be healthy; however, research has not shown antioxidant supplements to be beneficial in preventing diseases." The research on the benefits of antioxidants keeps coming and coming; for now, our best bet is to eat plenty of fruits and vegetables. And it can't hurt to seek out some that are higher in antioxidant activity than others.

Foods High in Antioxidants

Now that we have the basics down, let's get specific. In 2010, the Nutrition Journal published a database of the antioxidant power for over 3,100 foods, beverages, spices and more. Some experts discourage relying on numbers like these to build a healthy diet, until more is known. For example, the USDA dropped the ORAC database of antioxidant foods from its website in 2012, ostensibly over concerns that scientific evidence of actual human health benefits was lacking.

Nevertheless, it's interesting to look at the numbers. Antioxidant values can vary depending on where foods are grown and how they're processed, but the numbers give a general way to compare foods, and some tend to rise to the top. We've put together a list of five foods that are particularly high in antioxidants. And some of them may surprise you.

Espresso

14 mmol per 100 g (3 shots)

Let's hear it for the coffee lovers! Three espresso shots in one sitting may be a bit much, but cholorogenic acid, a potent antioxidant polyphenol found in coffee beans, is being studied for its health benefits.

Don't Miss These: Healthy Coffee Drink Recipes

Nuts

Walnuts: 22 mmol per 100 g (1 cup, halved)

Pecans: 9 mmol per 100 g (1 cup, halved)

Again, 100 grams of any nut is definitely way more than a standard serving—it's about four servings. However, the science shows that regular consumption of nuts may be good for your heart and brain health, among other benefits. They also provide a yummy crunch to salads, baked goods and more.

Pictured Recipe: Walnuts with Dark Chocolate

Dark Chocolate

11 mmol per 100 g (about one king-size bar)

The dark chocolate analyzed for this database contained 70-99% cocoa. Many store-bought chocolates have a lower percentage of cocoa than this (even bars labeled as dark), so be sure to read labels if you want to indulge in an antioxidant-rich way.

Berries

Blueberries: 9.2 mmol per 100 g (2/3 cup)

Berries may be one of the most potent sources of antioxidants on the list. Some less-available berries, such as dried bilberries, had numbers as high as 50, but the highest value for a common berry was blueberries. The antioxidants in blueberries especially seem to promote healthy aging and may have anticancer properties. It is well worth your while to sprinkle some blueberries on your yogurt parfait or keep some around as a sweet after-dinner snack.

Pictured Recipe: Fresh Berries with Warm Tequila-Lime Foam

Spices

Cinnamon: 115 mmol per 100 g (3/4 cup)

Allspice: 102 mmol per 100 g (3/4 cup)

Mint (dried): 72 mmol per 100 g (3/4 cup)

Cloves: 126 mmol per 100 g (3/4 cup)

Yes, 100 grams of any spice, which is around 3/4 cup, is an absurd amount for one sitting. However, these values show that using a variety of spices regularly can help boost your antioxidant intake. Using spices can also help you cut down on other less-nutritious flavor boosters, like salt or added sugar. For a more comprehensive list, check out the Top Fresh and Dried Herbs and Spices for Antioxidants.

Bottom Line

There are a lot of foods that contain a variety of antioxidants. Some heavy hitters include fruits, vegetables and spices, but foods like coffee and chocolate show high levels as well! Enjoy a variety of food, with an emphasis on being plant-based, in appropriate servings, and the antioxidants will follow.

Related: The Health Benefits of Eating a Plant-Based Diet and How to Get Started

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