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Do Antioxidants Prevent Cancer? 5 Things to Know

Antioxidants are often touted as must-haves for optimal health, particularly when it comes to fighting diseases like cancer. But is the buzz justified?

The compounds, which are present in foods and available as supplements, can play a key role in fighting free radicals. But they aren’t a cure-all, and some sources of antioxidants are more beneficial than others. Here’s a look at how antioxidants work, their role in preventing or treating cancer, and the best ways to get your fill.

1. Antioxidants can play a role in cancer prevention. Free radicals are unstable atoms that can damage cellular DNA in the body, which is thought to play a role in the development of cancer.

“Our bodies produce free radicals when we breathe or exercise, and we’re exposed to even more via environmental toxins like cigarette smoke, air pollution, or the sun’s UV rays,” says Tara Mauro, MS, RDN, CSO, a registered dietician specializing in oncology nutrition at Fox Chase Cancer Center. “They roam around the body and can cause chronic inflammation.”

Antioxidants work by tracking down free radicals and neutralizing their harmful effects. That helps keep more of the body’s cells healthy and less susceptible to becoming cancerous. 

2. You can get your antioxidant fill from food. The body makes some of its own antioxidants to fight free radicals, and you can get plenty more by eating a healthy diet. Brightly colored fruits and vegetables, like tomatoes, carrots, spinach, broccoli, sweet potatoes, strawberries, and citrus fruits, are top sources. Whole grains, nuts, seeds, and wheat germ serve up antioxidants too. “Your best bet is to go for a wide variety, since different foods have different antioxidants,” Mauro says.

3. Antioxidant supplements likely aren’t worth it. If antioxidants from food are good, it’s easy to assume that high-dose antioxidant supplements are even better. But there’s no evidence that antioxidant supplements can prevent cancer or other diseases. In fact, very high doses of certain antioxidants may actually increase the risk of some cancers.

Another thing to consider: Supplements contain isolated forms of single antioxidants, but that’s not the case with food.

“Food comes packaged with antioxidants as well as phytonutrients, vitamins, minerals, and fiber,” Mauro says. It’s possible that all of these compounds work together to exert their disease-fighting effects.

4. If you are facing cancer, it’s important to focus on good nutrition overall. Taking antioxidant supplements during cancer treatment doesn’t seem to have beneficial effects and research has shown that, in some cases, it could actually lead to worse outcomes. It’s never a bad idea to focus on getting antioxidants from fruits and vegetables, including when you have cancer, Mauro notes. But don’t stress about it too much. “It can be difficult to eat during cancer treatment,” she says. “Getting in any kind of calories is really what’s most helpful to maintain your weight.”

5. You should talk with your doctor if you take antioxidant supplements or are thinking about trying one. Supplements haven’t been shown to protect against cancer, and they have the potential to interact with other medications you might be taking or have a negative impact on cancer treatment.

“I’d recommend getting your antioxidants from food sources and avoiding supplements,” Mauro says. “But if you’re considering taking any kind of supplement, I always say patients should speak to their doctor first.”