What you need to know about antioxidants

Antioxidants neutralize free radicals — substances that occur naturally in the body but can damage cells and DNA.

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Food sources of natural antioxidants include fruits, vegetables, nuts and cocoa powder. Antioxidants neutralize free radicals.

Food sources of natural antioxidants include fruits, vegetables, nuts and cocoa powder.


Antioxidants are a nutrition topic that’s had staying power for decades because there is actual substance behind the hype.

Antioxidants neutralize free radicals — substances that occur naturally in the body but can damage cells and DNA.

“Antioxidants are simply compounds that protect cells against oxidation — or the effects of free radicals — and they’re found all around us, in many types of foods and drinks,” says Ginger Hultin, a registered dietician in Seattle who’s the author of “Anti-Inflammatory Diet Meal Prep” and “How to Eat to Beat Disease Cookbook.”

Hultin says the body is in constant flux and needs antioxidants to help naturally quench the oxidation that occurs by simply living — breathing, metabolizing, detoxing.

“These processes create natural free radical damage, and the balance is that we get antioxidants from the foods we eat,” she says.

Our bodies do a pretty good job of keeping free radicals in check by producing their own antioxidants — but poor diet and exposure to cigarette smoke, pollution, radiation and environmental toxins can produce more free radicals than your body can handle. The resulting oxidation can accelerate aging and increase the risk of heart disease, Type 2 diabetes, Alzheimer’s disease, Parkinson’s disease and cancer.

Counterintuitively, antioxidants in excess can be oxidant, and oxidation isn’t always bad, says Michelle Averill, an associate professor of occupational and health sciences at the University of Washington.

“It’s all a system, and we need oxidants and antioxidants in balance,” she says. “When our body increases oxidants, it’s not always negative. Sometimes, oxidants are a response to something happening in our system, and it tells our body to do something.”

We sometimes refer to certain nutrients and phytochemicals as antioxidants. It’s more accurate to say they have antioxidant properties. For example, vitamin C plays a role in the production of collagen, neurotransmitters and certain amino acids and also functions as an antioxidant.

“Vitamins and minerals contain antioxidants — including beta-carotene and vitamins C and E — but there are actually thousands of antioxidant compounds,” Averill says. “For example, all the types of polyphenols in tea, coffee, berries or chocolate. They’ve got flavanols, proanthocyanidins and anthocyanins, among many others.”

The minerals selenium and manganese have antioxidant properties. Averill says there could be hundreds of thousands of compounds with antioxidant properties.

Should you get antioxidants from supplements? The short answer is no.

In part, that’s because there can be too much of a good thing. There was a lot of excitement about antioxidant supplements in the 1990s, until researchers found that large doses increased some health risks — such as increased lung cancer risk in smokers taking beta-carotene — or didn’t deliver hoped-for benefits. It’s almost impossible to get too many antioxidants from food, and there’s no evidence taking antioxidant supplements works as well as eating antioxidant-rich food.

“It’s not that we specifically take X micronutrient to increase antioxidants in our bodies. It’s that we eat the foods that support the antioxidant balance in the body,” Averill says. “You can’t overcome an imbalance of antioxidants and oxidants through supplements.”

Each antioxidant serves a different function and is not interchangeable, so it’s important to get an array of antioxidants, fiber, and other nutrients from food. Fruits, vegetables, whole grains, beans and lentils, nuts and seeds, herbs and spices, coffee and cocoa,and green and black tea all have antioxidant compounds. All are plant foods.

“People would be amazed at how many antioxidants they can get naturally through food,” Hultin says. “Simply eating more common foods like carrots, apples, onions or parsley, for example, can provide a wide array of potent antioxidants.

Environmental Nutrition is an independent newsletter written by experts on health and nutrition.

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