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Doctor Decoded: What Are Free Radicals?

In this video, learn about free radicals and oxidative stress and how they can lead to the development of diseases.

Lauren Smith, MAAlexandra Schwarz, MD
Written by Lauren Smith, MA | Reviewed by Alexandra Schwarz, MD
Updated on June 15, 2022

You’ve probably seen plenty of headlines and health tips recommending berries to protect you from “free radicals.” This term has reached buzzword status, often dropped in a sentence to signify something sinister, but with little explanation of what it is. 

So … what are free radicals?

Free radicals are atoms or groups of atoms with an unpaired electron. To understand this, you’ll need a short chemistry lesson: Electrons like to run in pairs, and it makes them more stable. Thus, it’s less common to find a solo electron, and unpaired electrons usually just occur temporarily, during a chemical reaction.

Free radicals are formed naturally when cells metabolize oxygen, when your body digests food, or when you’re exposed to environmental things like pollution, cigarette smoke, or radiation. These are all chemical reactions that can result in unpaired electrons.

Free radicals in the body are highly reactive, and they can do damage to your cells and DNA. This may lead to gene mutations, which increase the risk for genetic disorders

Everyone has some amount of free radicals (and they have benefits in low amounts), but if free radicals accumulate, they may outnumber the antioxidants in the body, which are substances that help inhibit oxidation or remove oxidizing agents in the body. Since free radicals are a byproduct of oxidation, antioxidants help reduce the amount of free radicals.

An imbalance of free radicals and antioxidants results in oxidative stress, which is believed to be a risk factor in many common and chronic diseases that are linked to cell and DNA damage, including:

  • Arthritis

  • Cardiovascular diseases

  • Autoimmune diseases

  • And cancers.

As a result, antioxidants play an important role in managing the risk of diseases. Many fruits and veggies are rich in antioxidants, including vitamins A, C, and E. This might be *one* of the reasons—but not the only reason—that a diet rich in fruits and veggies tends to lower the risk of disease.

Want more tips to reduce your risk of disease?


Antioxidants. Washington, DC: MedlinePlus, U.S. National Library of Medicine. (Accessed on February 4, 2020 at https://medlineplus.gov/antioxidants.html.) 

Free radical. Merriam-Webster. (Accessed on February 4, 2020 at https://www.merriam-webster.com/dictionary/free%20radical.) 

View All References (2)

Pham-Huy LA, He H, Pham-Huy C. Free radicals, antioxidants in disease and health. Int J Biomed Sci. 2008 Jun;4(2):89-96.

Vitamin E. Washington, DC: MedlinePlus, U.S. National Library of Medicine. (Accessed on February 4, 2020 at https://medlineplus.gov/ency/article/002406.htm.)

GoodRx Health has strict sourcing policies and relies on primary sources such as medical organizations, governmental agencies, academic institutions, and peer-reviewed scientific journals. Learn more about how we ensure our content is accurate, thorough, and unbiased by reading our editorial guidelines.

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